SEC Form 10-K filed by ESS Tech Inc.

3/5/26 4:10:36 PM ET

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Table of Contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)


x			ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2025


o			TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from _______ to ________

Commission file number 001-39525

ESS Tech, Inc.

(Exact name of registrant as specified in its charter)


Delaware			98-1550150
(State or other jurisdiction of incorporation or organization)			(I.R.S. Employer Identification No.)
26440 SW Parkway Ave., Bldg. 83
Wilsonville, Oregon			97070
(Address of Principal Executive Offices)			(Zip Code)

(855) 423-9920

Registrant’s telephone number, including area code

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, $0.0001 par value per share

GWH

New York Stock Exchange

Warrants, each fifteen warrants exercisable for one share of common stock at an exercise price of $172.50

GWH.W

New York Stock Exchange

Securities registered pursuant to section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes o No x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No x

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports); and (2) has been subject to such filing requirements for the past 90 days. Yes x No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.


Large accelerated filer	o	Accelerated filer	o
Non-accelerated filer	x	Smaller reporting company	x
		Emerging growth company	o

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. o

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes o No x

The aggregate market value of the voting and non-voting common stock held by non-affiliates of the registrant as of the last business day of the registrant’s most recently completed second fiscal quarter, June 30, 2025, was approximately $13.6 million based on the closing sales price of our common stock on the New York Stock Exchange on June 30, 2025 of $1.33. Shares of the registrant’s common stock held by each executive officer, director, and holder of 10% or more of the outstanding common stock have been excluded because such persons may be deemed affiliates. This calculation does not reflect a determination that certain persons are affiliates of the registrant for any other purpose.

As of February 27, 2026, 27,173,757 shares of common stock, par value $0.0001 per share, were issued and outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive proxy statement relating to the 2026 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. Such proxy statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2025.

Table of Contents

TABLE OF CONTENTS


		Page
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS
PART I
Item 1.	Business	4
Item 1A.	Risk Factors	9
Item 1B.	Unresolved Staff Comments	45
Item 1C.	Cybersecurity	45
Item 2.	Properties	46
Item 3.	Legal Proceedings	47
Item 4.	Mine Safety Disclosures	47
PART II
Item 5.	Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	48
Item 6.	Reserved	48
Item 7.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	48
Item 7A.	Quantitative and Qualitative Disclosures About Market Risk	56
Item 8.	Financial Statements and Supplementary Data	57
Item 9.	Changes in and Disagreements with Accountants on Accounting and Financial Disclosures	86
Item 9A.	Controls and Procedures	86
Item 9B.	Other Information	86
Item 9C.	Disclosure Regarding Foreign Jurisdictions that Prevent Inspections	86
PART III
Item 10.	Directors, Executive Officers and Corporate Governance	87
Item 11.	Executive Compensation	87
Item 12.	Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	87
Item 13.	Certain Relationships and Related Transactions, and Director Independence	87
Item 14.	Principal Accounting Fees and Services	87
PART IV
Item 15.	Exhibits and Financial Statement Schedules	88
Item 16.	Form 10-K Summary	91
	SIGNATURES	92

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K, including, without limitation, statements in “Part II—Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations,” includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These forward-looking statements can be identified by the use of forward-looking terminology, including the words “believes,” “estimates,” “anticipates,” “expects,” “intends,” “plans,” “possible,” “may,” “might,” “will,” “potential,” “projects,” “predicts,” “continue,” “could,” “would” or “should,” or, in each case, their negative or other variations or comparable terminology. These words and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. These forward-looking statements, which are subject to risks, uncertainties and assumptions about us, may include projections of our future financial performance, our anticipated growth strategies and anticipated trends in our business.

These statements are based on management’s current expectations, but actual results may differ materially due to various factors, risks, and uncertainties, including, but not limited to:

•our financial and business performance, including financial projections and business metrics;

•changes in our strategy, future operations, financial position, estimated revenues and losses, projected costs, prospects and plans;

•the implementation, market acceptance and success of our technology and business model;

•our ability to increase efficiency and scale, including in a cost-effective manner;

•our expectations regarding our cost advantages compared to lithium-ion alternatives;

•the potential of our products and technology, including the benefits of such products and technology;

•developments and projections relating to our competitors and industry;

•the impact of the Russia-Ukraine conflict, geopolitical tensions involving China, the conflict between the U.S., Israel and Iran, tensions in the Middle East, U.S. interventions in Venezuela, and similar macroeconomic events, including global supply chain challenges, foreign currency fluctuations, instability in the financial markets, fluctuating inflation and interest rates and monetary policy changes, upon our and our customers’, contractors’, suppliers’ and partners’ respective businesses;

•our expectations regarding our ability to obtain and maintain intellectual property protection and manufacture and sell our products and services without infringing on the rights of others;

•our future capital requirements and sources and uses of cash;

•our ability to obtain funding for our operations and the impact of any cash conservation or fundraising measures;

•our business, expansion plans and opportunities;

•our relationships with third parties, including our customers, contractors, insurance providers and suppliers;

•issues related to the shipment, installation, and operation of our products;

•issues related to contract execution, including customer site readiness and acceptance of our products;

•our ability to enter into commercial or strategic partnerships or transactions and recognize benefits therefrom;

•the outcome of any known and unknown litigation and regulatory proceedings;

•issues related to government tax laws, tax credits, subsidies, economic incentives, and regulatory changes;

•our ability to successfully deploy the proceeds from the Business Combination (as defined herein), other investments in our Company and any borrowing under our existing or future credit agreements;

•our ability to satisfy certain New York Stock Exchange (“NYSE”) listing requirements and maintain a trading market for our common stock;

•other risks and uncertainties discussed in “Part I—Item 1A. Risk Factors” and elsewhere in this Annual Report on Form 10-K.

The forward-looking statements contained in this Annual Report on Form 10-K are based on our current expectations and beliefs concerning future developments and their potential effects on us. There can be no assurance that future developments affecting us will be those that we have anticipated. These forward-looking statements are made as of the date

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of this Annual Report on Form 10-K and involve a number of risks, uncertainties (some of which are beyond our control) and other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, those factors described in “Part I—Item 1A. Risk Factors” and elsewhere in this Annual Report on Form 10-K. Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws. These risks and others described in “Part I—Item 1A. Risk Factors” may not be exhaustive.

By their nature, forward-looking statements involve risks and uncertainties because they relate to events and depend on circumstances that may or may not occur in the future. We caution you that forward-looking statements are not guarantees of future performance and that our actual results of operations, financial condition and liquidity, and developments in the industry in which we operate may differ materially from those made in or suggested by the forward-looking statements contained in this Annual Report on Form 10-K. In addition, even if our results or operations, financial condition and liquidity, and developments in the industry in which we operate are consistent with the forward-looking statements contained in this Annual Report on Form 10-K, those results or developments may not be indicative of results or developments in subsequent periods.

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PART I

ITEM 1. BUSINESS

Unless the context otherwise requires, all references in this Annual Report on Form 10-K to “ESS,” “we,” “us,” “our,” or the “Company” refer to ESS Tech, Inc.

Business Combination

ESS Tech, Inc. (“Legacy ESS”) was founded in 2011 and became a publicly traded company through a business combination with a special purpose acquisition company named ACON S2 Acquisition Corp. (“STWO”) which changed its name to ESS Tech, Inc. upon closing (the “Business Combination”). As a result of the Business Combination, Legacy ESS survived and became a wholly owned subsidiary of ESS Tech, Inc. On March 31, 2024, Legacy ESS merged with ESS Tech, Inc. leaving ESS Tech, Inc. as the successor legal entity.

Business Overview

ESS is a long-duration energy storage company specializing in iron flow battery technology. We design and produce long-duration batteries predominantly using earth-abundant materials that we believe can be cycled over 20,000 times without capacity fade based on lab-scale results. Because our batteries are designed to operate using an electrolyte of primarily salt, iron and water, our products are environmentally sustainable and substantially recyclable or reusable. Our batteries provide flexibility to grid operators and energy assurance for commercial and industrial customers. Our technology addresses energy delivery, duration and cycle-life in a single battery platform that compares favorably to lithium-ion batteries, the most widely deployed alternative technology. We design and build this core technology, including battery stacks, electrolyte and electrolyte health management solutions into a core power train that is then sold in our current product focus: the gigawatt-hour scale, fully configurable Energy Base and core power trains that can be assembled at the customer site into complete storage solutions. Our original product offering included the Energy Warehouse and Energy Center, which we are not currently offering for sale. With each battery deployed, we further our mission to accelerate the transition to a zero-carbon energy future with increased grid reliability.

Our batteries are non-flammable and can operate in a wide range of temperatures from -15°C to 50°C with minimal auxiliary loads. This allows our energy storage products to be located in sites where lithium-ion batteries cannot be placed due to fire, chemical or explosion risks. In addition, our batteries are environmentally sustainable, predominantly utilizing readily sourced materials and recyclable or reusable components.

We believe that as we are able to increase our production, our per unit costs will decrease, allowing our battery technology to be priced more competitively. When comparing products on a lifetime levelized cost of storage (“LCOS”) basis, which is the total cost of the investment in an electricity storage technology divided by its cumulative delivered electricity, we expect our batteries to be less expensive than lithium-ion alternatives for storage durations greater than eight hours, which we believe is the economic maximum for lithium-ion technologies. Our cost advantage increases as the storage duration extends beyond eight hours because of the scalable nature of our technology.

Energy storage solutions of various sizes and durations must be installed throughout global electrical grids to enable decarbonization in line with global climate objectives. Our energy storage products are intended to supply long-duration power across this expanding spectrum of use cases. As described below in the subsection entitled “Our Technology and Products,” we believe our energy storage products will be capable of addressing customer needs across multiple use cases and markets. We are an early mover in long-duration energy storage and we believe our products will enable more rapid implementation of renewable energy while also improving grid stability. The safety, flexibility and durability of our energy storage products enable customers to use them in nearly any location globally. Examples of use cases range from localized energy storage at commercial and industrial sites to grid-scale use cases, such as peaker plant replacement and grid stabilization.

Our Technology and Products

Our long-duration iron flow batteries are the product of nearly 50 years of scientific advancement. In the 1970s, researchers first developed the concept of iron flow batteries. Despite realizing the batteries’ promising ability to store energy, these researchers found that the reaction between the positive and negative sides created hydroxide formations that clogged the electrodes and reduced the activity of the electrolytes. Hydroxide formation caused rapid degradation in early iron flow batteries after only a few cycles. Unable to prevent the hydroxide from forming, these scientists were forced to abandon their work.

Our founders, Craig Evans and Dr. Julia Song, began advancing this technology in 2011 and formed Legacy ESS. Building upon this promising concept, our team has significantly enhanced the technology, improved round-trip efficiency and developed an innovative and patented solution to the hydroxide build-up problem. Our proprietary solution to eliminate the

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hydroxide formation is known as the Proton Pump, which works by utilizing hydrogen generated by side reactions on the negative electrode. The Proton Pump converts the hydrogen back into protons in the positive electrolyte. This process eliminates the hydroxide and stabilizes the electrolytes’ pH level. The Proton Pump allows the electrolyte to be used for the 20,000 cycle-design without capacity fade.

Our iron flow batteries store energy by converting electrical energy into chemical energy. Each battery module is made up of one or more cells and each of these cells is made up of a negative electrode and a positive electrode, and these two electrodes are separated by a porous separator. On the positive side (positive electrode) of the battery during charge, ferrous iron (Fe+2) is oxidized into ferric iron (Fe+3) and on the negative side (negative electrode) of the battery, ferrous iron is reduced to iron metal. The porous separator is used to minimize the positive and the negative electrolyte from mixing, which helps improve the coulombic efficiency of the battery. The positive and negative electrolytes are stored separately in tanks outside of the battery and this electrolyte is constantly pumped in and out of the battery while in operation. To convert the chemical energy back to electrical energy, the reaction is reversed; on the positive side of the battery, ferric iron is reduced to ferrous iron and on the negative side, metallic iron is oxidized into ferrous iron. During these charge and discharge cycles, the pH of the positive and negative electrolyte can change dramatically. The Proton Pump ensures that the electrolyte pH remains stable and clear of any hydroxides.

Our iron flow batteries store energy by charging positive and negative electrolyte tanks that are separated by a membrane. In order to release energy, we generate a reaction between the tanks via the membrane. The power generated is a factor of the membrane size, while the duration of storage we can offer is a factor of the tank sizes and the addition of electrolytes to the tank, which can be accomplished at a relatively low cost. The duration of stored energy can be independently varied from the power. This allows for low marginal costs of energy, making our technology attractive for long-duration energy storage.

Using our iron flow battery technology, we have developed products to provide reliable, safe, long-duration energy storage solutions. Our third and current offering, the gigawatt-hour Energy Base storage product, is designed with a fully configurable layout that integrates with any site location and that allows the power (the rate of electricity flow) to be decoupled from the capacity (the total amount of energy held). This, combined with an expectation of 20,000 cycles and rapid response time, means that the performance of each Energy Base can be tailored to meet individual customer needs. As a result, users have the flexibility to use the battery for various use cases simultaneously on a project. We continue to perform warranty and maintenance activities for our first and second product generations, the Energy Warehouse and Energy Center, that remain under contract in the field.

The same core technology can enable energy storage solutions designed to meet specific customer needs, particularly when much larger (<5-100MW) requirements exist. In this arrangement, we offer core components configured as power trains, which can then be assembled on-site with various ‘balance of system’ components, including tanks, pumps, and plumbing, to create fully integrated storage solutions. These balance of system components are commercially available products used across a variety of industries and applications. ESS has developed and will continue to expand its documentation, reference design and recommendations to allow customers and partners to build and operate integrated storage solutions based on our core technology.

For all of our energy storage products, the intellectual property and points of differentiation are contained within the core technology components, the Proton Pump, power module, Battery Management System and electrolyte. These components are protected by trade secrets, patents (both granted and in process) and years of research. The balance of system components required to build complete solutions are intentionally designed to be easily produced using broadly available pumps, tanks and other equipment and easily fabricated enclosures, allowing energy storage products to be assembled and deployed almost anywhere at an efficient cost.

Customers

Our current and potential customers include utilities, Independent Power Providers (“IPPs”) and Commercial and Industrial (“C&I”) end users. We intend to serve customers in both ‘behind-the-meter’ and ‘front-of-the-meter’ markets. In behind-the-meter applications, customers will use our energy storage products to reduce energy costs, integrate with renewable energy solutions to achieve corporate sustainability goals, and to enhance their energy resiliency. Behind-the-meter customers may include data centers, microgrids, critical infrastructure assets and commercial and industrial customers.

Front-of-the-meter customers, in contrast, are primarily utilities experiencing high rates of renewable energy penetration and requiring energy storage to help balance the grid, and IPPs who can leverage energy storage to improve the economics of renewable energy projects. These customers use our energy storage products to store energy on a utility scale that they can then utilize or sell to their customers when needed and ensure overall grid reliability at a time of increasing demand for

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energy and grid reliability. Over time, we expect our customer base to expand to include additional types of energy suppliers and an even broader variety of use cases.

We believe our solutions are well-suited to address these diverse applications and use cases due to their flexibility, longevity and safety, among other factors.

Suppliers

Our batteries are made predominantly of earth-abundant, environmentally sustainable materials. These materials are considerably less expensive than rare earth metals that make up other batteries and as a result make up a low percentage of the total costs for our batteries. Because these materials are widely available, there are multiple suppliers for each input. In addition, we use limited high-cost materials such as platinum in our manufacturing. While supply chain disruptions have in the past impacted the ability of some of our suppliers to deliver certain components of our batteries to us in a timely manner as described in the section entitled “Part I—Item 1A. Risk Factors—Risks Related to Our Technology, Products and Manufacturing—We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We also depend on vendors for the shipping of our energy storage products. Quality issues or delays in our supply or delivery chain and shipments could harm our ability to manufacture, supply and commercialize our energy storage products,” the mechanical elements and control systems of our batteries are comprised of commercially available equipment that can be supplied by multiple manufacturers.

Partnerships

We have various partnerships, including:

•OneBeacon Insurance: Through OneBeacon, we offer project surety capacity and corporate bonding options to our customers.

•Export-Import Bank of the United States: The Export-Import Bank of the United States (“EXIM”) is the official export credit agency of the United States. EXIM equips U.S. businesses with the financing tools necessary to compete for global sales when private sector lenders are unable or unwilling to provide financing. Our energy storage products are qualified by EXIM, which can provide financing for qualified overseas buyers.

Research & Development

Since January 1, 2019, we have invested approximately $184.7 million in improving our technology and bringing our energy storage products to market. Our research and development efforts are conducted in Oregon and supported by our approximately 21 research and development employees.

We aim to be a leader in the long-duration energy storage market, and in order to do so, it is essential to continue our ongoing research and development activities. We have a research and development roadmap for additional breakthroughs to extend our technology advantages further. Expanding our technological capabilities to alternate chemistries and technologies is also a long-term goal of our research and development team.

Intellectual Property

Intellectual property is an integral differentiator for our business, and we rely upon a combination of patents, copyrights and trade secrets to protect our proprietary technology. We believe that we have enforceable intellectual property protection over all critical design elements as well as the key enabling technologies for iron flow batteries. We have developed a significant patent portfolio. We have over 315 patents that are granted, applied for or in the pipeline for application, and an undisclosed number of trade secrets. Without taking into account any possible patent term adjustments or extensions, the earliest our current, issued patents will begin to expire in 2028. We continually review our efforts to assess the existence and patentability of new proprietary technology. We intend to leverage our iron flow expertise to drive innovation and are pursuing additional technological advancements.

Competition

The energy storage industry is highly competitive. The declining cost of renewable energy, the decrease in battery costs, improving battery technologies, and public financial support in the form of grants and tax incentives are shifting customer demands causing the industry to evolve and expand. The main competitive factors in the energy storage market include, but are not limited to, safety and reliability, duration, performance and uptime, operational flexibility, asset life length and cyclability, ease of integration, operability in extreme temperatures, environmental sustainability, historical track record, and field-proven technology.

With the rising demand for clean electric power solutions with lower greenhouse gas emissions, there has been a transition to renewable energy sources and increasing penetration of distributed energy infrastructure. The proliferation of intermittent generating resources has created new challenges to electric grid stability, and thus an opportunity for an

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increased role for long-duration energy storage solutions. In recent years, there have been, and in the future there may continue to be, more unpredictable weather events including extreme temperatures, hurricanes and wildfires. Our technology can operate efficiently and effectively in these extreme weather conditions. Our key competitors include different energy storage technologies such as lithium-ion batteries, lithium metal batteries, lithium iron phosphate batteries, sodium-ion batteries including those developed by Contemporary Amperex Technology Co., Limited, vanadium or zinc bromine batteries, sodium sulfur batteries, compressed air, hydrogen, fuel cell and pumped-storage hydropower. Key competitors in the traditional lithium-ion space include Contemporary Amperex Technology Co. Limited, LG Chem, Ltd., Samsung Electronics Co., Ltd., Sungrow Power Supply Co., Ltd., and Tesla, Inc. Key competitors in the non-lithium-ion space include EnerVenue, Inc., Invinity Energy Systems, CellCube, CMBlu Energy AG, Energy Dome, Energy Vault, Enerox GmbH, Eos Energy Enterprises, Inc., Form Energy, Highview Power PTY Ltd., Hydrostor, Lockheed Martin (GridStar Flow), and Malta Inc.. Many of our competitors have substantially greater financial, marketing, personnel and other resources than we do. Although we may be small compared to some of our competitors, we believe we are well-positioned to compete with them in the market supported by our innovative iron flow battery technology, strategic partnerships and premier leadership team with a proven track record of success.

New technologies may enter the market that may have additional or superior advantages to our offerings. We believe there remains significant government support available for energy storage technologies, and a variety of newer and emerging companies have announced plans to develop energy storage products using a variety of technologies, including compressed air, thermal energy, and solid-state batteries among others. Although many of these companies are not in commercial production today, they may in the future offer solutions that become competitive with our offerings. We intend to continuously improve our product offerings and maintain robust research and development efforts in order to stay ahead of existing and emerging competitors.

Government Regulations and Compliance

We operate in the heavily regulated energy sector. Our operations are subject to a variety of federal, state and local regulations governing manufacturing, project development, transportation, environmental, grid interconnection, and market participation matters. As such, there are a variety of federal, state and local regulations and agencies that impact our operations. As a participant in the renewable energy sector specifically, there are federal and state regulations, tax incentives and support mechanisms that impact our business. In addition, renewable energy and energy storage is a priority for many national, state and local governments.

On the U.S. federal level, tax credits remain in place that incentivize both the manufacturing and deployment of renewable energy and battery storage. The Inflation Reduction Act of 2022 established advanced manufacturing production credits and investment tax credits for energy storage. The One Big Beautiful Bill Act (H.R. 1) (the “OBBB”), enacted in July 2025, preserved these tax credits but introduced complexity by requiring compliance with certain “foreign entity of concern” (FEOC) rules. Beginning in 2026, energy storage technology will need to comply with these rules, which generally restrict entities linked to adversarial nations, particularly China, from accessing the benefits of U.S. tax credits including by placing limitations on the eligibility of equipment procured from such entities for such credits. As a manufacturer of energy storage systems, we may be eligible for advanced manufacturing production credits to produce eligible battery components. For project deployments, battery energy storage systems are eligible for investment tax credits. These credits are available for standalone storage systems regardless of whether they are charged by renewable energy sources, allowing project developers to monetize and sell the tax credits they receive from the creation of their projects. Additionally, battery storage projects are eligible for accelerated depreciation via the federal government’s Modified Accelerated Cost Recovery System. These policies provide tax and financing advantages for battery storage projects, lower the capital requirements for renewable energy projects to be developed and open a new source of funding for these projects, although the complexity introduced by the FEOC rules, in particular as the industry is still awaiting guidance, may counteract these benefits and limit our and our customers’ ability to take advantage of such incentives.

State incentives have also driven growth in the deployment of renewable energy and energy storage. States with high Renewable Portfolio Standards (“RPS”), such as California, have seen greater deployment of renewables than states with similar renewable resources that lack such requirements. Other states, such as Texas, have seen significant renewable deployment driven by favorable market conditions. In both types of markets, the deployment of intermittent renewables is straining the electric grid and thus driving demand for energy storage.

We have made sales in Australia, where government incentive programs support renewable energy and energy storage deployment. The Australian federal government and several state governments have established renewable energy targets and energy storage procurement goals that may drive future demand for our products.

All of these governmental programs supporting demand for our products depend on continued legislative support and favorable regulatory implementation. Changes in policy guidance or budget priorities could reduce or eliminate these benefits, including through repeal of modification of tax credits, weakening of state renewable energy mandates, or

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reduction in grid modernization funding. Any such changes would adversely affect demand for our products and our financial position. Additionally, new or modified regulations could impose compliance costs or affect our operations, which could materially harm our business.

In addition to benefiting from governmental laws and regulations supporting energy storage, we are subject to federal, state and local requirements related to the environment, transportation, health, safety and employment. Our manufacturing operations are subject to environmental regulations, and our products are subject to regulations addressing safety and reliability. We are also subject to state utility commission requirements, grid interconnection timelines, as well as other permitting processes for project development. Our Oregon manufacturing facility is subject to the requirements of the Occupational Safety and Health Act, local wage regulations and rigorous health and safety regulations in the State of Oregon.

Human Capital Management

We pride ourselves on our clean, innovative technology and our employees are dedicated to our strategic mission to deliver reliable, resilient and safe renewable energy storage solutions to communities worldwide. As of December 31, 2025, we employed 62 full-time employees, based primarily at our headquarters in Wilsonville, Oregon.

In order to achieve our mission to create a reliable, resilient, and safe renewable energy future, we are committed to investing in our employees and building a respectful and diverse work environment. We provide equal employment opportunities to all persons regardless of race, age, color, gender, sexual orientation, national origin, physical or mental disability, religion, or any other characteristic protected by federal, state, or local law. Our employees are key to our success as a company, and we are committed to attracting, developing and retaining the best talent. Many of our employees are highly skilled in technical areas related to energy storage, and our philosophy is to both develop talent from within as well as strategically hire qualified individuals with the skills, experience and industry knowledge necessary to contribute to the growth and success of ESS. We also supplement our workforce with consultants or independent contractors as necessary. In order to retain top talent, we have designed our compensation program to provide employees with competitive compensation and benefits consistent with positions, skill levels, experience, knowledge, and geographic location. We are also continuously working to improve our recruiting, retention and development processes as our operations grow.

Executive management assists our board of directors (the “Board”) in its oversight of human capital management including with respect to corporate culture, diversity and inclusion, recruiting, retention, attrition, talent management, career development and progression, succession and employee relations.

The success of our business is connected to the well-being of our team members. Accordingly, we are committed to the health, safety and wellness of our team members worldwide. To date, we have not experienced any work stoppages and we consider our relationship with our employees to be good. None of our employees are represented by a labor union or subject to a collective bargaining agreement.

Available Information

Our investor relations website is located at https://investors.essinc.com/, our Company X account is located at https://x.com/ESS_info, and our corporate LinkedIn account is located at https://www.linkedin.com/company/energy-storage-systems/. The information on, or that can be accessed through, our website and the aforementioned X account and LinkedIn account is not incorporated by reference into this Annual Report and should not be considered to be part of this Annual Report on Form 10-K unless expressly noted. Further, our references to website URLs are intended to be inactive textual references only. We may use our investor relations website and the aforementioned X account and LinkedIn account to post important information for investors, including news releases, analyst presentations, and supplemental financial information, and as a means of disclosing material non-public information and for complying with our disclosure obligations under Regulation FD. Accordingly, investors should monitor our investor relations website and the aforementioned X account and LinkedIn account, in addition to following press releases, filings with the Securities and Exchange Commission (the “SEC”) and public conference calls and webcasts.

We will file or furnish periodic reports and amendments thereto, including our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K (and amendments to those reports), proxy and information statements and other information filed or furnished pursuant to Sections 13(a) and 15(d) of the Exchange Act with the SEC. The SEC maintains a website that contains reports, proxy and information statement, and other information regarding issuers that file electronically, which may be accessed through the SEC at http://www.sec.gov. Our reports, amendments thereto, proxy statements and other information are also made available, free of charge, on our investor relations website as soon as reasonably practicable after we electronically file or furnish such information with the SEC. All statements made in any of our securities filings, including all forward-looking statements or information, are made as of the date of the document in

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which the statement is included, and we do not assume or undertake any obligation to update any of those statements or documents unless we are required to do so by law.

ITEM 1A. RISK FACTORS

Investing in our securities involves a high degree of risk. Before making an investment decision, you should consider carefully the risks and uncertainties described below, together with all of the other information in this Annual Report on Form 10-K, including our financial statements and related notes thereto included elsewhere in this Annual Report on Form 10-K and in our other filings with the SEC. Our business, operating results, financial condition or prospects could also be harmed by risks and uncertainties not currently known to us or that we currently do not believe are material. If any of the risks actually occur, our business, operating results, financial condition and prospects could be adversely affected. In that event, the market price of our common stock could decline, and you could lose part or all of your investment. References to “we,” “our,” or “us” generally refer to ESS, unless otherwise specified.

Summary Risk Factors

Our business is subject to numerous risks and uncertainties. The following is a summary of the principal risks we face:

•We face significant barriers in our attempts to produce our energy storage products, certain of our energy storage products are still under development, and we may not be able to successfully develop our energy storage products at commercial scale. If we cannot successfully overcome those barriers, our business will be negatively impacted and could fail;

•We are in the early stage of commercialization. In addition, certain aspects of our technology have not been fully field tested. If we are unable to develop our business and effectively commercialize our energy storage products as anticipated, we may not be able to generate significant revenues or achieve profitability;

•We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We also depend on vendors for the shipping of our energy storage products. Quality issues or delays in our supply or delivery chain and shipments could harm our ability to manufacture, supply and commercialize our energy storage products;

•We have experienced in the past, and may experience in the future, delays, disruptions, or quality control problems in our manufacturing operations;

•We may be unable to adequately control the costs associated with our operations and the components necessary to build our energy storage products, and if we are unable to reduce our cost structure and effectively scale our operations in the future, our ability to become profitable may be impaired;

•Our cost reduction strategy may not succeed or may be significantly delayed, which may result in our inability to achieve profitability;

•We rely on complex machinery for our operations and the production of our iron flow batteries involves a significant degree of risk and uncertainty in terms of operational performance and costs;

•Our future success depends in part on our ability to increase our production capacity, and we may not be able to do so in a cost-effective manner. If we elect to expand our production capacity by constructing or leasing one or more new manufacturing facilities, we may encounter challenges relating to the construction, management and operation of such facilities;

•If required maintenance is performed incorrectly or if maintenance requirements exceed our current expectations, this could adversely affect our reputation, prospects, business, financial condition and results of operations;

•We have a history of losses and have to deliver significant business growth to achieve sustained, long-term profitability and long-term commercial success;

•Failure to deliver the benefits offered by our technology, or the emergence of improvements to competing technologies, could reduce demand for our energy storage products and harm our business;

•Our plans are dependent on the development of market acceptance of our products and long duration energy storage technology;

•As deployment of our energy storage products increases, we will incur corresponding warranty obligations and our warranty obligations may be significant. If our energy storage products do not operate successfully in the field or if we are unable to manage our warranty costs, our business and ability to generate revenue and achieve profitability could fail;

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•Our relationships with related parties, SBE, an affiliate of SoftBank Group Corp., and Honeywell, are subject to various risks which could adversely affect our business and future prospects;

•We may face regulatory challenges to or limitations on our ability to sell our products directly in certain markets. Expanding operations internationally could expose us to additional risks;

•If we fail to protect, or incur significant costs in defending, our intellectual property and other proprietary rights, then our business and results of operations could be materially harmed; and

•As we endeavor to expand our business, we will incur significant costs and expenses, which could outpace our cash reserves. We will need to raise additional capital in the near future, and it may not be available on acceptable terms, if at all. Unfavorable conditions or disruptions in the capital and credit markets may also adversely impact business conditions and the availability of credit.

The following risk factors apply to our business and operations. These risk factors are not exhaustive, and investors are encouraged to perform their own investigation with respect to our business, financial condition and prospects. We may face additional risks and uncertainties that are not presently known to us, or that we currently deem immaterial, which may also impair our business. The following discussion should be read in conjunction with the consolidated financial statements and notes to the consolidated financial statements included in this Annual Report on Form 10-K.

Risks Related to Our Technology, Products and Manufacturing

We face significant barriers in our attempts to produce our energy storage products, certain of our energy storage products are still under development, and we may not be able to successfully develop our energy storage products at commercial scale. If we cannot successfully overcome those barriers, our business will be negatively impacted and could fail.

Producing long-duration iron flow batteries that meet the requirements for wide adoption by commercial and utility-scale energy storage applications is a difficult undertaking. We are still in the early stage of commercialization and have faced and may yet face significant challenges in completing the development of our various energy storage products and in producing our energy storage products in commercial volumes. Some of the challenges that could prevent the successful scaling of our iron flow battery products include difficulties with (i) increasing manufacturing capacity to produce the volume of cells needed for our energy storage products, (ii) installing and optimizing higher volume manufacturing equipment, (iii) packaging our batteries to ensure adequate cycle-life, (iv) cost reduction, (v) qualifying new vendors and subcomponents, (vi) expanding supply chain capacity, (vii) the completion of rigorous and challenging battery safety testing required by our customers or partners, including but not limited to, performance, life and abuse testing and (viii) the development of the final manufacturing processes and specifications.

As of December 31, 2025, we had limited deployment of our energy storage products and there may be significant yield, cost, performance and manufacturing process challenges to be solved as we ramp up commercial production and use. Our core technology components are also still under development for integration into third-party systems. We have encountered and are likely to further encounter engineering challenges as we seek to increase the capacity, duration, efficiency and reliability of our batteries. If we are not able to overcome these barriers in developing and producing our iron flow batteries, our business could fail. If the performance characteristics or other specifications of the batteries fall short of our targets, our sales, product pricing and margins would likely be adversely affected.

We are in the early stage of commercialization. In addition, certain aspects of our technology have not been fully field tested. If we are unable to develop our business and effectively commercialize our energy storage products as anticipated, we may not be able to generate significant revenues or achieve profitability.

The growth and development of our operations will depend on the successful commercialization and market acceptance of our energy storage products and our ability to manufacture products at scale while timely meeting customers’ demands. There is no certainty that, once shipped, our products will operate over the long term as expected, and we may not be able to generate sufficient customer confidence in our latest designs and ongoing product improvements or to perform under our contracts with customers. There are inherent uncertainties in our ability to predict future demand for our energy storage products and, as a consequence, we may have inadequate production capacity to meet demand, or alternatively, have excess available capacity. Our inability to predict the extent of customer adoption of our proprietary technologies in the already-established traditional energy storage market makes it difficult to evaluate our future prospects.

As of December 31, 2025, we had limited Energy Warehouse and Energy Center products fully deployed. Production and productized versions of our Energy Base product and core component technology are still under development. We have experienced various quality and performance issues with units that have been installed and although we have worked to repair or replace any known issues, our inability to address these or potential new issues effectively may have cost and warranty implications and may affect the acceptance of our products in the market. In addition, although we believe our

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iron flow battery technology is field tested and ready for sale, there are no assurances that our proprietary technologies, such as our Proton Pump, will operate as expected and with consistency over time. We have also experienced grid compatibility and other site integration issues that are not within our control, which has required and will continue to require an adjustment of our power electronics and energy management system interface on a site-by-site basis. Certain operational characteristics have never been witnessed in the field and as we deploy more of our products, we may discover further aspects of our technology that require improvement. Any of these issues could delay existing contracts and new sales, result in order cancellations, result in significant warranty obligations, and negatively impact the market’s acceptance of our technology. If we experience significant delays, order cancellations or warranty claims, or if we fail to develop and install our energy storage products in accordance with contract specifications, then our operating results and financial condition could be adversely affected. In addition, there is no assurance that if we alter or change our energy storage products in the future, that the demand for these new products will develop, which could adversely affect our business and revenues. If our energy storage products are not deemed desirable and suitable for purchase and we are unable to establish a customer base, we may not be able to generate significant revenues or attain profitability.

We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We also depend on vendors for the shipping of our energy storage products. Quality issues or delays in our supply or delivery chain and shipments could harm our ability to manufacture, supply and commercialize our energy storage products.

We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products, including power module components (e.g., bipolar plates, frames, end plates and separators), chemicals, and electronic components. We will need to maintain and significantly grow our access to key raw materials and control our related costs. We use various raw materials and components to construct our energy storage products, including polypropylene, iron and potassium chloride, that are critical to our manufacturing process. We also rely on third-party suppliers for injection molded parts and power electronics which undergo a qualification process that can take months.

The cost of components for our iron flow batteries, whether manufactured by our suppliers or by us, depends in part upon the prices and availability of raw materials. In recent periods, we have seen an increase in costs for a wide range of materials and components and such increases may continue, particularly if we again experience high rates of inflation. Additionally, supply chain disruptions and access to materials have impacted and continue to impact our vendors and suppliers’ ability to deliver materials and components to us in a timely manner. We have experienced significant disruptions to key supply chains, shipping times, shipping availability, manufacturing times, and increases in associated costs, both with respect to the sourcing of supplies and the delivery of our products. We have experienced and may continue to experience supply chain issues, delays to deliveries, and vendor quality issues, as well as increases in our supply costs of many of our key components, including polypropylene, resin, power electronics, and circuit board components. Such issues have also affected the ramping up of our automated production line. If we experience similar issues in the future, including any delays of deliveries of additional manufacturing automation equipment that we require, they may further delay our ability to produce and deliver our products and to recognize additional revenue (see also “Part I. Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Components of Results of Operations—Revenue”).

We expect prices for materials to fluctuate over time. Available supply for materials may also be unstable, depending on market conditions and global demand for these materials, including as a result of increased global production of batteries and energy storage products. For example, our Proton Pump is manufactured with certain raw materials, which not only include precious and non-precious metals but also carbon, graphite and thermoplastics, the prices of which have historically fluctuated on a cyclical basis and depend on a variety of factors over which we have no control. We have also experienced increased prices and/or inconsistent quality and supply of other electrical components and power module components including frames, end plates and separators. Any reduced availability of these materials may impact our ability to manufacture our products and any further increases in their prices may reduce our profitability if we cannot recoup the increased costs through increased prices for our products.

In addition, the tariffs put in place by the United States, Russia-Ukraine conflict, geopolitical tensions involving China, the conflict between the U.S., Israel and Iran, tensions in the Middle East, and U.S. interventions in Venezuela have led to disruption, instability and volatility in the global markets and certain industries and may also lead to further disruptions that could negatively impact our operations and our supply chain. The U.S. government and other governments have imposed severe sanctions and export controls against Russia and Russian interests and continue to impose additional sanctions and controls. While the Company has not experienced any significant impacts from these disruptions to date, future impacts are unknown and they could adversely affect our business, supply chain, partners or customers.

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contractors, suppliers and partners. As a result of these macroeconomic forces, during 2024 and 2025, we experienced supply constraints, increased shipping delays for certain customer contracts, and delays in timing of payments from some of our customers. We believe some or all of these negative trends may continue into 2026.

We depend on third-party vendors for the shipping of our energy storage products. We have in the past faced and may yet again face disruptions in the logistics sector, making it more challenging to find trucks to ship our products. The shipping of our products to customers internationally in a timely, cost-effective, and secure manner that does not damage our products has proved and may again prove to be challenging. The failure to deliver our products in a timely fashion or within budget may also harm our brand, prospects and operating results. In addition, if our batteries are damaged during shipment, we may be required to repair or replace such units.

We do not know whether we will be able to maintain long-term supply relationships with our critical suppliers, or, if required, secure new long-term supply relationships on terms that will allow us to achieve our objectives.

We continually evaluate and qualify new suppliers. However, there are a limited number of suppliers for some of the key components of our products and we have, to date, fully qualified only a very limited number of such suppliers. Therefore, we have limited flexibility in changing suppliers. In addition, we have had issues with inconsistent quality and supply of certain key power module components. We do not know whether we will be able to maintain long-term supply relationships with our critical suppliers, or, if required, secure new long-term supply relationships on terms that will allow us to achieve our objectives. A supplier’s failure to develop and supply components in a timely manner, to supply components that meet our quality, quantity, cost requirements or our technical specifications, to support our warranty claims, or our inability to obtain alternative sources of these components on a timely basis or on terms acceptable to us, could each harm our ability to manufacture and commercialize our energy storage products. Low volume requirements from third-party suppliers in the near term could strain vendor relationships or result in less favorable pricing and thus increased launch costs. In addition, to the extent the processes that our suppliers use to manufacture components are proprietary, we may be unable to obtain comparable components from alternative suppliers, all of which could harm our business, financial condition and results of operations.

In the long term, we intend to supplement certain components from our suppliers by manufacturing them ourselves, which we believe will be more efficient and manufacturable at greater volumes and cost-effective than currently available components. However, our efforts to develop and manufacture such components have required and may require significant investments, and there can be no assurance that we will be able to accomplish this in the timeframes that we have planned or at all. If we are unable to do so, we may have to curtail our product production or procure additional raw materials and components from suppliers at potentially greater costs, either of which may harm our business and operating results.

We have experienced in the past, and may experience in the future, delays, disruptions, or quality control problems in our manufacturing operations.

Our manufacturing and testing processes require significant technological and production process expertise and modification to support our projected business objectives. We have already experienced various issues related to the scaling up of the manufacturing process and while we seek to prevent the reoccurrence of such issues, there can be no assurance that such issues will not reoccur in the future. In addition, any change in our processes could cause one or more production errors, requiring a temporary suspension or delay in our production line until the errors can be researched, identified, and properly addressed and rectified. This may occur particularly as we introduce and transition to new products, modify our engineering and production techniques, and/or expand our capacity. In addition, our failure to maintain appropriate quality assurance processes could result in increased product failures, loss of customers, increased warranty reserves, increased production, and logistical costs and delays. Any of these developments could lead to current and potential customers cancelling or postponing their purchases of our products, which could have a material adverse effect on our business, financial condition and results of operations.

We may be unable to adequately control the costs associated with our operations and the components necessary to build our energy storage products, and if we are unable to reduce our cost structure and effectively scale our operations in the future, our ability to become profitable may be impaired.

Our ability to become profitable in the future will not only depend on our ability to successfully market our products but also to control our manufacturing costs. If we are unsuccessful in our cost-reduction plans or if we experience design or manufacturing defects or other failures as a result of these design changes, we could incur significant manufacturing and re-engineering costs. In addition, we will require significant capital to further develop and grow our business and expect to incur significant expenses, including those relating to research and development, raw material procurement, leases, sales and distribution as we build our brand and market our products, and general and administrative costs as we scale our operations. If we are unable to cost-efficiently design, manufacture, market, sell and distribute our energy storage products, our margins, profitability and prospects would be materially and adversely affected.

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Substantial increases in the prices of raw materials would increase our operating costs and could adversely affect our profitability. The price of oil likewise fluctuates on a cyclical basis and any increase in price may affect the cost of manufacturing, distributing and transporting our products. If we are unable to pass any such increased costs to our customers, this could have a material adverse effect on our business, financial condition and results of operations.

In order to achieve our business plan and reach profitability, we must continue to increase the number of units sold and reduce the manufacturing and development costs for our products. Currently, production costs for our units significantly exceed their selling price. Additionally, certain of our existing customer contracts were entered into based on projections regarding cost reductions that assume continued advances in our manufacturing and services processes that we may be unable to realize. The cost of components and raw materials, for example, has been increasing and could continue to increase in the future, offsetting any successes in reducing our manufacturing costs. Any such increases could slow our growth and cause our financial results and operational metrics to suffer. In addition, we may face increases in our other expenses including increases in wages or other labor costs as well as installation, marketing, sales or related costs. In order to expand into new markets (especially markets in which the price of electricity from the grid is lower), we will need to continue to reduce our costs. Increases in any of these costs or our failure to achieve projected cost reductions could adversely affect our results of operations and financial condition and harm our business and prospects. If we are unable to reduce our cost structure in the future, we may not be able to achieve profitability, which could have a material adverse effect on our business and our prospects.

Further, we have not yet produced our products at volume and our expected cost advantage for the production of these products at scale, compared to conventional lithium-ion cells, will require us to achieve rates of throughput, use of electricity and consumables, yield, and rates of automation demonstrated for mature battery, battery material, and manufacturing processes, that we have not yet achieved. If we are unable to achieve these targeted rates, our business will be adversely impacted.

Our cost reduction strategy may not succeed or may be significantly delayed, which may result in our inability to achieve profitability.

Our ability to successfully implement our overall business strategy relies on our ability to reduce development and manufacturing costs in the future and thereby lower our selling price. Our cost reduction strategy is based on the assumption that increases in production will result in economies of scale. In addition, our cost reduction strategy relies on advancements in our manufacturing process, global competitive sourcing, engineering design, reducing the cost of capital and technology improvements (including stack life and projected power output). Its successful implementation also depends on a number of factors, some of which are beyond our control, including the impact of inflation, tariffs and the timely delivery of key supplies at reasonable prices. For example, our current supply imbalance may result in additional costs that exceed our current expectations. There is no assurance that our cost reduction strategy will be successful and failure to achieve our cost reduction targets could have a material adverse effect on our business, financial condition and results of operations.

We rely on complex machinery for our operations and the production of our iron flow batteries involves a significant degree of risk and uncertainty in terms of operational performance and costs.

We rely heavily on complex machinery for our operations and manufacturing and we are pioneering the use of this equipment for the large-scale manufacturing of iron flow battery products. The work required to integrate this equipment into the production of our iron flow battery product is time intensive and requires us to work closely with the equipment provider to ensure that it works properly for our unique iron flow battery technology. This integration work will involve a significant degree of uncertainty and risk and may result in a delay in the scaling up of production or result in additional cost to our iron flow batteries.

Our manufacturing facility utilizes large-scale machinery, particularly for the automated production line. Such machinery is likely to suffer unexpected malfunctions from time to time and will require repairs and spare parts to resume operations, which may not be available when needed. Unexpected malfunctions of our production equipment may significantly affect the intended operational efficiency or yield. Some examples would be inadequate bonding of the battery cells resulting in overboard or internal leakage, damage to the separator, or cracked bipolar or monopolar plates. In addition, because this equipment has limited history building iron flow battery products, the operational performance and costs associated with this equipment can be difficult to predict and may be influenced by factors outside of our control, such as, but not limited to, failures by suppliers to deliver necessary components of our energy storage products in a timely manner and at prices and volumes acceptable to us, environmental hazards and remediation, difficulty or delays in obtaining governmental permits, damages or defects in systems, industrial accidents, fires, seismic activity and other natural disasters.

Operational problems with our manufacturing equipment could result in the personal injury to or death of workers, the loss of production equipment, damage to manufacturing facilities, monetary losses, delays and unanticipated fluctuations in

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production. In addition, operational problems may result in environmental damage, administrative fines, increased insurance costs and potential legal liabilities. All of these operational problems could have a material adverse effect on our business, cash flows, financial condition or results of operations.

Our future success depends in part on our ability to increase our production capacity, and we may not be able to do so in a cost-effective manner. If we elect to expand our production capacity by constructing or leasing one or more new manufacturing facilities, we may encounter challenges relating to the construction, management and operation of such facilities.

In order to grow our business, we will need to increase our production capacity. For example, our current manufacturing capacity may not be sufficient to meet our planned production targets and we are currently seeking to expand our capacity. Our ability to plan, develop and equip additional manufacturing facilities is subject to significant risks and uncertainties, including but not limited to the following:

•The expansion or construction of any manufacturing facilities will be subject to the risks inherent in the development and construction of new facilities, including risks of delays and cost overruns as a result of factors outside our control, which may include delays in government approvals, burdensome permitting conditions, and delays in the delivery or installation of manufacturing equipment and subsystems that we manufacture or obtain from suppliers, similar to or more severe than what we have experienced recently.

•In order for us to expand internationally, we anticipate entering into strategic partnerships, joint ventures and licensing agreements that allow us to add manufacturing capability outside of the United States. Adding manufacturing capacity in any international location will subject us to new laws and regulations including those pertaining to labor and employment, environmental and export/import. In addition, any such expansion brings with it the risk of managing larger scale foreign operations.

•We may be unable to achieve the production throughput necessary to achieve our target annualized production run rate at our current and future manufacturing facilities.

•Manufacturing equipment may take longer and cost more to engineer and build than expected and may not operate as required to meet our production plans.

•We may depend on third-party relationships in the development and operation of additional production capacity, which may subject us to the risk that such third parties do not fulfill their obligations to us under our arrangements with them.

•We may be unable to obtain financing needed to build out our current and future manufacturing facilities.

•We may be unable to attract or retain qualified personnel.

If we are unable to expand our manufacturing facilities, we may be unable to further scale our business, which would negatively affect our results of operations and financial condition. We cannot provide any assurances that we would be able to successfully establish or operate an additional manufacturing facility in a timely or profitable manner, or at all, or within any expected budget for such a project. The construction of any such facility would require significant capital expenditure and result in significantly increased fixed costs. If we are unable to transition manufacturing operations to any such new facility in a cost-efficient and timely manner, then we may experience disruptions in operations, which could negatively impact our business and financial results. Further, if the demand for our products decreases or if we do not produce the expected output after any such new facility is operational, we may not be able to spread a significant amount of our fixed costs over the production volume, thereby increasing our per product fixed cost, which would have a negative impact on our business, financial condition and results of operations.

In addition, if any of our partners suffer from capacity constraints, deployment delays, work stoppages or any other reduction in output, we may be unable to meet our delivery schedule, which could result in lost revenue, damages, and deployment delays that could harm our business and customer relationships. If the demand for our iron flow batteries or our production output decreases or does not rise as expected, we may not be able to spread a significant amount of our fixed costs over the production volume, resulting in a greater than expected per unit fixed cost, which would have a negative impact on our financial condition and our results of operations.

Our ability to expand our manufacturing capacity would also greatly depend on our ability to hire, train and retain an adequate number of manufacturing employees, in particular employees with the appropriate level of knowledge, background and skills. Should we be unable to hire, train, or retain such employees, our business and financial results could be negatively impacted.

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We have in the past and may be compelled in the future to undertake product recalls or take other actions, which could adversely affect our business, prospects, operating results, reputation and financial condition.

We have in the past and may be compelled in the future to undertake product recalls. For example, in the past, we had to recall our Gen I battery modules due to vendors not properly manufacturing the parts to our specifications and we have also had to replace, and may again be required to replace, certain components of our products delivered to customers to date. Any quality issues can result in single module failures or can result in a cascade of numerous failures. Failures in the field can result in a single module replacement or may result in a total recall depending on the severity or contamination to the remainder of the system.

Any product recall in the future may result in adverse publicity, damage our reputation and adversely affect our business, financial condition and results of operations. In the future, we may, voluntarily or involuntarily, initiate a recall if any of our products or components prove to be defective or noncompliant with applicable safety standards. Such recalls, whether caused by systems or components engineered or manufactured by us or our suppliers, would involve significant expense, damages and diversion of management’s attention and other resources, which could adversely affect our brand image in our target market and our business, financial condition and results of operations.

If required maintenance is performed incorrectly or if maintenance requirements exceed our current expectations, this could adversely affect our reputation, prospects, business, financial condition and results of operations.

Our energy storage products require periodic maintenance or refurbishment, such as the cleaning or replacement of air filters or other components, inspection and re-torquing of electrical or mechanical fasteners, and the replenishment of hydrogen. Maintenance items are intended to be scheduled on a periodic basis but may vary depending on system operations. We currently rely on our customers that do not have service agreements with us or that perform maintenance that is not covered by such agreements to follow our product operations and maintenance manuals. In addition, we have had, and in the future may continue to have, components such as our electrolyte rebalancing cell that have a shorter service life than anticipated and require replacement in lieu of maintenance. Furthermore, there is risk of harm to persons or property if individuals performing maintenance do not follow applicable maintenance or safety protocols. Any such incident or harm would likely lead to adverse publicity and potentially a safety recall, decisions or mandates to temporarily halt production or implement an extended suspension of field operations, and expenses related to carrying out site remediation, revising our training programs and updating our maintenance manual, and could also adversely affect our reputation, customer’s willingness to place future orders, our operating results and prospects, business, financial condition and results of operations. We have had, and in the future may continue to have, incidents of failure to maintain or perform required maintenance correctly that damage or adversely affect the performance of our energy storage products and/or result in the leakage of electrolyte. For example, the performance of maintenance procedures out of sequence by Company personnel in the past led to an over-pressurization event at a customer site and a sudden release of the cap to the electrolyte storage tank. The tank was not otherwise damaged and no injuries occurred, but the incident resulted in a significant spill event that we promptly reported and has since been closed with the county of jurisdiction. We conducted a full investigation and have implemented remediation steps but there is risk of damage to product or property or personal injury if such steps are not followed in the future.

In addition, for customers that have purchased maintenance services from us, unforeseen issues may arise that may require maintenance beyond what we currently expect. We have no experience providing maintenance on a large scale and since our existing and potential customers are geographically dispersed, if any recurring or significant one-off maintenance is required, this could increase our costs.

Risks Related to Our Business and Industry

Our expectations for future operating and financial results and market growth rely in large part upon assumptions and analyses developed by us. If these assumptions or analyses prove to be incorrect, our actual operating results may be materially different from our anticipated results.

We operate in rapidly changing and competitive markets and our expectations for future performance are subject to the risks and assumptions made by management with respect to our industry. Operating results are difficult to predict because they generally depend on our assessment of the timing of adoption of our technology and energy storage products, which is uncertain. Expectations for future performance are also subject to significant economic, competitive, industry and other uncertainties and contingencies, all of which are difficult or impossible to predict and many of which are beyond our control, and subsequent developments may affect such expectations. As discussed elsewhere in this Annual Report on Form 10-K, any future sales and related future cash flows may not be realized in full or at all. Furthermore, our planned expansion into new revenue streams such as franchising opportunities for our energy storage products may never be realized or achieve commercial success, whether because of lack of market adoption of our energy storage products, competition or otherwise. Important factors that may affect the actual results and cause our operating and financial results

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and market growth expectations to not be achieved include risks and uncertainties relating to our business, industry performance, the regulatory environment, general business and economic conditions and other factors described under the section entitled “Cautionary Note Regarding Forward-Looking Statements” in this Annual Report on Form 10-K.

In addition, expectations for future performance also reflect assumptions that are subject to change and do not reflect revised prospects for our business, changes in general business or economic conditions or any other transaction or event that has occurred or that may occur and that was not previously anticipated. Our revenue and operating results have fluctuated in the past and are likely to fluctuate in the future. For example, our revenue declined from $6.3 million for the year ended December 31, 2024 to $1.6 million for the year ended December 31, 2025. These fluctuations may occur on a quarterly and annual basis due to a number of factors, many of which are beyond our control. In addition, long-term expectations by their nature become less predictive with each successive year. There can be no assurance that our future financial condition or results of operations will be consistent with our expectations or with the expectations of investors or securities research analysts, which may cause the market price of our common stock to decline. If actual results differ materially from our expectations, we may be required to make adjustments in our business operations that may have a material adverse effect on our financial condition and results of operations.

We have a history of losses and have to deliver significant business growth to achieve sustained, long-term profitability and long-term commercial success.

We have had net losses on a U.S. GAAP basis in each fiscal year since our inception. For the years ended December 31, 2025 and December 31, 2024, we had $63.4 million and $86.2 million in net losses, respectively, and as of December 31, 2025, we had $845.8 million in accumulated deficit. In order to achieve profitability as well as long-term commercial success, we must continue to execute our plan to expand our business, which will require us to deliver on our existing global sales pipeline in a timely manner, increase our production capacity, reduce our manufacturing and warranty costs, competitively price and grow demand for our products, and seize new market opportunities by leveraging our proprietary technology and our manufacturing processes for novel solutions and new products. Failure to do one or more of these things could prevent us from achieving sustained, long-term profitability.

We expect, based on our sales pipeline, to grow revenues over time. However, our revenue may not grow as expected for a number of reasons, many of which are outside of our control, including a decline in global demand for iron flow battery storage products, increased competition, or our inability to accelerate our pipeline development and fulfill orders to continue to capitalize on growth opportunities. If we are not able to generate and grow revenue and raise the capital necessary to support our operations, we may be unable to continue as a going concern.

There is substantial doubt about our ability to continue as a “going concern”.

We will require substantial additional funds to continue our operations. Our cash and cash equivalents and short-term investments were $22.0 million at December 31, 2025. Given our recurring history of losses and an insufficient amount of cash available to fund our ongoing operations for the next year, we have concluded that there is a substantial doubt regarding our ability to continue as a going concern for a period of at least 12 months beyond the filing of this Annual Report on Form 10-K. Any such inability to continue as a going concern may result in our stockholders losing their entire investment. There is no guarantee that we will become profitable or secure additional financing on acceptable terms. Further, the inclusion of disclosures expressing substantial doubt about our ability to continue as a going concern could materially adversely affect our stock price and our ability to raise new capital or enter into partnerships or other agreements.

We have prepared our consolidated financial statements on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities and commitments in the normal course of business. Our consolidated financial statements included in this Annual Report on Form 10-K do not include any adjustments to reflect the possible inability to continue as a going concern within at least 12 months after the issuance of such financial statements.

There is no assurance nonbinding pre-orders or framework agreements will be converted into binding orders or that orders will be completed.

Our business model is focused on building relationships with large customers. To date, we have engaged in limited marketing activities and we have only a limited number of contracts with customers. Certain of our energy storage products are still subject to further design evolution and until the time that the design and development of our energy storage products stabilizes, and until we are able to scale up our marketing function to support sales, there will be uncertainty as to customer demand for our energy storage products. Demand for our energy storage products by independent energy developers may depend upon a bankability determination by institutional sources of project finance capital and that determination may be difficult to obtain. The potentially long wait from the time an order is made until the time our energy storage products are delivered, and any delays beyond expected wait times, could also impact user decisions on whether to ultimately make a purchase. There is no assurance that nonbinding pre-orders or framework agreements will be converted

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into binding orders or sales. Even if we are able to obtain binding orders, customers may limit their volume of purchases initially as they assess our products and whether to make a broader transition to our energy storage products. This may be a long process and will depend on the safety, reliability, efficiency and quality of our energy storage products, as well as the support and service that we offer. It will also depend on factors outside of our control, such as general market conditions and site capacity, that could impact customer buying decisions. As a result, there is significant uncertainty regarding demand for our energy storage products and the pace and levels of growth that we will be able to achieve.

In addition, some of the systems we have shipped to date have not met the specifications set forth in the relevant purchase contracts, resulting in additional installation time and costs in order to receive customer acceptance of such units. If we are unable to meet contractual performance specifications of our units, customers may bring claims against us or choose to cancel or postpone orders, which would adversely affect our business, financial condition and results of operations.

Failure to deliver the benefits offered by our technology, or the emergence of improvements to competing technologies, could reduce demand for our energy storage products and harm our business.

We believe that, compared to lithium-ion batteries, our energy storage solutions offer significant benefits, including using widely available, low-cost materials with no rare mineral components, being substantially recyclable or reusable at end-of-life, having a 25-year product design life, and having a wide thermal operating range that reduces the need for fire suppression and heating (except where otherwise required by applicable law), ventilation and air conditioning equipment, which would otherwise be required for use with lithium-ion batteries. While we believe that total cost of ownership pricing is the key consideration, lithium-ion battery pack selling costs have decreased significantly over time and may decrease further in the future. While we have also decreased our selling costs, if we are unable to further decrease our costs or if our manufacturing costs increase, if our or our customers’ expectations regarding the operation, performance, maintenance and disposal of our energy storage products are not realized, or if local regulations require alterations to our equipment, then we could have difficulty marketing our energy storage products as a superior alternative to already-established technologies. This would also impact the market reputation and adoptability of our energy storage products.

We also currently market our energy storage products as having superior design cyclability to other energy storage solutions on the market. However, in general, flow batteries have suffered challenges running multiple cycles over their lifetime without experiencing degradation in storage capacity and, in particular, earlier iterations of our iron flow batteries, specifically our first-generation units, failed at cycling reliably. All of our first-generation units (except for one) have been returned to us and the continuing risk of product failure on our first-generation units is limited. However, there is no assurance that our later-generation units will not fail or have issues cycling in the future if our technology does not operate as expected. If our technology is inadequate or our energy storage solutions fail to operate as expected or designed, our warranty costs may be significant and current and potential customers may choose to cancel or postpone orders or seek alternative solutions for their energy storage needs, which would adversely affect our business, financial condition and results of operations.

In addition, developments of existing and new technologies could improve the cost and usability profile of such alternative technologies, reducing any relative benefits currently offered by our energy storage products, which would negatively impact the likelihood of our energy storage products gaining market acceptance.

Our plans are dependent on the development of market acceptance of our products and long duration energy storage technology.

Our plans are dependent upon market acceptance of our products and our ability to effectively educate potential customers on the benefits of our technology. Iron flow batteries represent an emerging market, and we cannot be sure that potential customers will accept iron flow batteries as a replacement for traditional power sources. In particular, traditional lithium-ion batteries, which are already produced on a large global scale and have widespread market acceptance, offer higher power density and round-trip efficiency than our iron flow batteries. If customers were to place greater value on power density and round-trip efficiency over what we believe to be the numerous other advantages of our technology, then we could have difficulty positioning our iron flow batteries as a viable alternative to traditional lithium-ion batteries and our business would suffer.

As is typical in a rapidly evolving industry, demand and market acceptance for recently introduced products and services are subject to a high level of uncertainty and risk. Many of our early customers purchased our products on a pilot basis and it is difficult to predict with certainty the size of the energy storage market and its growth rate. The development of a market for our products may be affected by many factors that are out of our control, including:

•the cost competitiveness of our products including availability and output expectations and total cost of ownership;

•the future costs associated with renewable energies;

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•perceived complexity and novelty of our technology and customer reluctance to try a new product;

•the market for energy storage solutions and government policies that affect those markets;

•government incentives, mandates or other programs favoring zero carbon energy sources;

•local permitting and environmental requirements;

•customer preference for lithium-ion based technologies, including but not limited to the power density offered by lithium-ion batteries; and

•the emergence of newer, more competitive technologies and products.

If a sufficient market fails to develop or develops more slowly than we anticipate, we may be unable to recover the losses we will have incurred in the development of our products, and we may never achieve profitability.

Our future growth and success depend on our ability to sell effectively to large customers.

Many of our potential customers are electric utilities and C&I businesses that tend to be large enterprises. Therefore, our future success will depend on our ability to effectively sell and deliver our products to such large customers. Sales to these end-customers involve risks that may not be present (or that are present to a lesser extent) with sales to smaller customers. These risks include, but are not limited to, (i) increased purchasing power and leverage held by large customers in negotiating contractual arrangements with us and (ii) longer sales cycles and the associated risk that substantial time and resources may be spent on a potential end customer that elects not to purchase our solutions.

Large organizations often undertake a significant evaluation process that results in a lengthy sales cycle. In addition, product purchases by large organizations are frequently subject to budget constraints, multiple approvals and unanticipated administrative, processing and other delays. Finally, large organizations typically have longer implementation cycles, require greater product functionality and scalability, require a broader range of services, demand that vendors take on a larger share of risks, and expect greater payment flexibility. All of these factors can add further risk to business conducted with these potential customers.

We operate in highly competitive energy industries and there is increasing competition. Many of our competitors and potential competitors have substantially greater financial, marketing, personnel and other resources than we do and if we do not compete effectively, our competitive positioning and our operating results will be harmed.

The energy storage markets continue to evolve and are highly competitive. Many of our current and potential competitors are large entities at a more advanced stage in development and commercialization than we are and, in some cases, have substantially greater financial, marketing, personnel and other resources, to increase their market share. Our key competitors include different energy storage technologies such as lithium-ion batteries, lithium metal batteries, lithium iron phosphate batteries, sodium-ion batteries, vanadium or zinc bromine batteries, sodium sulfur batteries, compressed air, hydrogen, fuel cell and pumped-storage hydropower. Key competitors in the traditional lithium-ion space include Contemporary Amperex Technology Co. Limited, LG Chem, Ltd., Samsung Electronics Co., Ltd., Sungrow Power Supply Co., Ltd., and Tesla, Inc. Key competitors in the non-lithium-ion space include EnerVenue, Inc., Invinity Energy Systems, CellCube, CMBlu Energy AG, Energy Dome, Energy Vault, Enerox GmbH, Eos Energy Enterprises, Inc., Form Energy, Highview Power PTY Ltd., Hydrostor, Lockheed Martin (GridStar Flow), and Malta Inc. If our competitors continue to penetrate the energy storage market, our prospects for gaining market share will be diminished.

We expect competition in energy storage technology to intensify due to a regulatory push for lower-carbon energy sources, including intermittent sources such as wind and solar, continuing globalization, and consolidation in the energy industry. Developments in alternative technologies or improvements in energy storage technology made by competitors may materially adversely affect the sales, pricing and gross margins of our products.

Some of our current and potential competitors have longer operating histories and greater financial, technical, marketing and other resources than we do. These factors may allow our competitors to respond more quickly or efficiently than we can to new or emerging technologies. These competitors may engage in more extensive research and development efforts, undertake more far-reaching marketing campaigns and adopt more aggressive pricing policies, which may allow them to more effectively compete for new energy storage projects and customers.

Our project awards and sales pipeline may not convert to contracts or may be delayed, which may have a material adverse effect on our revenue and cash flows.

We expect a significant portion of the business that we will seek in the foreseeable future will be awarded through competitive bidding against other energy storage technologies and other forms of power generation. The competitive bidding process involves substantial costs and a number of risks, including the significant cost and managerial time to prepare bids and proposals for contracts that may not be awarded to us, the length of time required to conclude the process,

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even if successful and our failure to accurately estimate the resources and costs that will be required to fulfill any contract we win. In addition, following a contract award, we may encounter significant expense, delay or contract modifications or award revocation as a result of our competitors protesting or challenging contracts awarded to us in competitive bidding. Our failure to compete effectively in this procurement environment could adversely affect our revenue and/or profitability.

Some of the project awards we receive and orders we accept from customers require certain conditions or contingencies (such as permitting, interconnection, financing or regulatory approval) to be satisfied, some of which are outside of our control. Certain awards are cancellable or revocable at any time prior to contract execution. The time periods from receipt of an award to execution of a contract, or receipt of a contract to installation may vary widely and are determined by a number of factors, including the terms of the award, governmental policies or regulations that go into effect after the award, the terms of the customer contract and the customer’s site requirements. These same or similar conditions and contingencies may be required by financiers in order to draw on financing to complete a project. If these conditions or contingencies are not satisfied, or changes in laws affecting project awards occur, or awards are revoked or cancelled, project awards may not convert to contracts, and installations may be delayed or canceled. In addition, contracted customers may have specific site requirements and interface technology or experience delays in preparing their site for equipment installation, which has caused, and in the future may continue to cause, delays with respect to delivery and installation and potentially our ability to recognize revenue. This could have an adverse impact on our revenue and cash flow and our ability to complete construction of a project.

We also bear the risk of non-payment or late payments by our customers. In the near term, we will depend on a relatively small number of customers for a significant portion of our revenue. If these customers fail to pay us or pay us late, cash flow from operations are impacted and our operating results and financial condition could be harmed. If a contract is cancelled due to the customer’s inability to pay, the redeployment of our product(s) could be expensive, and it may take time to find a replacement customer to whom our product(s) could be redeployed in a cost-effective manner.

Our contracted sales are subject to the risk of termination by the contracting party.

The majority of our commercial contracts contain provisions which allow the customer to terminate an agreement if certain conditions are not met, including the failure to meet performance specifications or for other defaults, or for extended force majeure. Our customers are also subject to force majeure events and may issue such notices to us. In addition, certain of our contracts can be terminated by the customer simply for convenience. We have experienced in the past, and may experience in the future, order cancellations or contract terminations, which could have an adverse impact on our revenues, longer term potential and market reputation, which would have an even greater impact on our ability to achieve future sales.

We may not be able to accurately estimate the future supply and demand for our products and services, which could result in a variety of inefficiencies in our business and hinder our ability to generate revenue. If we fail to accurately predict our manufacturing requirements, we could incur additional costs or experience delays.

We are a company with a limited operating history. Having only recently transitioned from research and development activities to commencing commercial production and sales, it is difficult to predict our future revenues and appropriately budget for our expenses, and we may have limited insight into trends that may emerge and affect our business. We anticipate being required to provide expectations of our demand to our current and future suppliers prior to the scheduled delivery of products to potential customers. Currently, there is limited historical basis for making judgments on the demand for our products and services or our ability to develop, manufacture, and deliver iron flow batteries, or our profitability in the future. If we overestimate our manufacturing requirements, our suppliers may have excess inventory, which indirectly would increase our costs. If we underestimate our manufacturing requirements, our suppliers may have inadequate inventory or capacity, which could interrupt manufacturing of our products and result in delays in shipments and revenues. In addition, lead times for materials and components that our suppliers order may vary significantly and depend on factors such as the specific supplier, contract terms and demand for each component at a given time. If we fail to order sufficient quantities of product components in a timely manner, the delivery of batteries to our potential customers could be delayed, which would harm our business, financial condition and results of operations.

If we fail to manage our growth effectively, we may be unable to execute our business plan, maintain high levels of customer service, or adequately address competitive challenges.

We intend to continue to expand our business significantly within existing and new markets. This growth has placed, and any future growth may place, a significant strain on management, operational, and financial infrastructure. In particular, we will be required to expand, train, and manage any new employees and scale and otherwise improve our information technology (“IT”) infrastructure in tandem with any headcount growth. Management will also be required to maintain and expand our relationships with customers, suppliers, and other third parties and attract new customers and suppliers, as well as manage multiple geographic locations.

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Our current and planned operations, personnel, customer support, IT, information systems, and other systems and procedures might be inadequate to support future growth and may require us to make additional unanticipated investment in our infrastructure. Our success and ability to scale our business will depend, in part, on our ability to manage these changes in a cost-effective and efficient manner. If we cannot manage our growth, then we may be unable to take advantage of market opportunities, execute our business strategies, or respond to competitive pressures. This could also result in declines in quality or customer satisfaction, increased costs, difficulties in introducing new offerings, or other operational difficulties. Any failure to effectively manage growth could adversely impact our business and reputation.

We have signed product sales contracts and have entered into service agreements with customers. If we do not meet the obligations under these agreements or if our estimates of the projected useful life of our energy storage products are inaccurate, our business and financial results could be adversely affected.

We have entered into service agreements with certain customers for our energy storage products with terms of up to 10 years. Under the provisions of these contracts, we will provide services to maintain, monitor, and repair our energy storage products to meet minimum operating levels. While we have conducted tests to determine the overall life of our energy storage products, we have not run certain of our energy storage products over their projected useful life or in all potential conditions prior to large scale commercialization. As a result, we cannot be sure that these energy storage products will last to their expected useful life or perform as anticipated in all conditions, which could result in warranty claims, performance penalties, maintenance, on-going servicing and battery module replacement costs and/or a negative perception of our energy storage products.

Further, the occurrence of chronic defects or other chronic performance problems with respect to our deployed energy storage products could result in loss of customers, legal claims, including warranty and service agreement claims, or diversion of our resources, including through increased service and warranty expenses or financial concessions, and increased insurance costs. The costs incurred in correcting any material defects in our deployed energy storage products may be substantial and could adversely affect our business, financial condition, and results of operations.

Our customers also depend on our support organization to resolve performance issues relating to our energy storage products. Any failure to maintain high-quality support services, or a market perception that we do not maintain high-quality and highly responsive customer support, could adversely affect our reputation, our ability to sell our energy storage products to existing and prospective customers, and our business, financial condition and results of operations.

Our ability to proceed with projects under development and complete construction of projects on schedule and within budget are subject to contractual, technology, operating and commodity risks as well as market conditions that may affect our operating results.

Our ability to proceed with projects under development and complete construction of projects on schedule and within budget may be adversely affected by escalating costs and lead times for materials and components, tariffs, export controls, labor and regulatory compliance, inability to obtain necessary permits, interconnections or other approvals on acceptable terms or on schedule and by other factors. If any development project or construction is not completed, is delayed or is subject to cost overruns, we could become obligated to make delay or termination payments or become obligated for other damages under contracts, experience diminished returns or write off all or a portion of our capitalized costs in the project. Each of these events could have an adverse effect on our business, financial condition and results of operations. We currently face and will continue to face significant competition, including from products using other energy sources that may be lower priced or have preferred environmental characteristics.

We compete on the basis of our energy storage products’ reliability, efficiency, environmental sustainability and cost. Technological advances in alternative energy products, improvements in the electric grid or other sources of power generation, or new battery technologies or market entrants may negatively affect the development or sale of some or all of our energy storage products or make our energy storage products less economically attractive, non-competitive or obsolete prior to or after commercialization. Significant decreases in the price of alternative technologies, or significant increases in the price of the materials we use to build our energy storage products could have a material adverse effect on our business because other generation sources could be more economically attractive to consumers than our energy storage products.

We invest significantly in research and development, and to the extent our research and development investments are not directed efficiently or do not result in material enhancements to our products and technologies, our business and results of operations would be harmed.

A key element of our strategy is to invest significantly in our research and development efforts to enhance the features, functionality, performance and ease of use of our products and technologies to address additional applications that will broaden the appeal of our products and technologies and facilitate their broad use. Research and development projects can be technically challenging and expensive. As a result of the nature of research and development cycles, there will be delays between the time we incur expenses associated with research and development activities and the time we are able to offer

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compelling enhancements to our products and technologies and generate revenue, if any, from those activities. If we expend a significant amount of resources on research and development efforts that do not lead to the successful introduction of new products, functionality or improvements that are competitive in our current or future markets, our business and results of operations will suffer.

The loss of one or more members of our senior management team and other key personnel or our failure to attract and retain qualified personnel may adversely affect our business and our ability to achieve our anticipated level of growth.

We depend on the continued services of our senior management team and other key personnel, each of whom would be difficult to replace. The loss of any such personnel, or the inability to effectively transition to their successors, could have a material adverse effect on our business and our ability to implement our business strategy. All of our employees, including our senior management, are free to terminate their employment relationships with us at any time. Any changes to our senior management team, including hires or departures, could cause disruption to our business and have a negative impact on operating performance, while these operational areas are in transition.

Additionally, our ability to attract qualified personnel, including senior management and key technical personnel, is critical to the execution of our growth strategy. Competition in the labor market, including for qualified senior management personnel and highly skilled individuals with technical expertise, is intense. We face and are likely to continue to face challenges identifying, hiring, and retaining qualified personnel in all areas of our business, and we can provide no assurance that we will find suitable successors as transitions occur. In addition, integrating new employees into our team, and key personnel in particular, could prove disruptive to our operations, require substantial resources and management attention, and ultimately prove unsuccessful. Our failure to attract and retain qualified personnel in all areas of our business, including senior management and other key technical personnel, could limit or delay our strategic efforts, which could have a material adverse effect on our business, financial condition and results of operations.

Further, we have in the past and may again in the future need to furlough or reduce in force a substantial number of our employees, which may yield unintended consequences, such as delays or a reduction in our ability to achieve our business objectives, making future retention and recruiting of qualified personnel more difficult, unexpected attrition, decline in employee productivity, negative impacts on internal controls over financial reporting, and reduced employee morale, which may cause our employees to seek alternative employment.

Significant changes to our leadership team and the resulting management transitions might harm our future operating results.

We have recently experienced significant changes to our leadership team, and these transitions may result in the loss of certain institutional or technical knowledge. Further, the transition could potentially disrupt our operations and relationships with employees, suppliers, partners, and customers due to added costs, operational inefficiencies, decreased employee morale and productivity and increased turnover. We must successfully recruit and integrate new leadership team members within our organization to achieve our operating objectives; as such, the leadership transition may temporarily affect our business performance and results of operations while the new members of our leadership team become familiar with our business and their positions. In addition, our competitors may seek to use this transition and the related potential disruptions to gain a competitive advantage over us. Furthermore, these changes may increase our dependency on employees that remain with us, who are not contractually obligated to remain employed with us and may leave at any time. Any such departure could be particularly disruptive given that we are already experiencing leadership transitions and, to the extent we experience additional management turnover, competition for top management is high such that it may take some time to find a candidate that meets our requirements. Our future operating results depend substantially upon the continued service of our key personnel and in significant part upon our ability to attract and retain qualified management personnel. If we are unable to mitigate these or other similar risks, our business, results of operations and financial condition may be materially and adversely affected.

Our results of operations may fluctuate from quarter to quarter, which could make our future performance difficult to predict and could cause our results of operations for a particular period to fall below expectations, resulting in a decline in the price of our common stock.

Our products take months to manufacture and prepare for delivery and any revenue in future periods may fluctuate based on underlying customer arrangements. Further, we expect our arrangements may have multiple deliverables and performance obligations and the amount and timing of recognizing revenue for those different performance obligations may vary which could cause our revenue to fluctuate. Our revenues also depend on a number of other factors, some of which are beyond our control, including the impact of supply chain issues (see also “—Risks Related to Our Technology, Products and Manufacturing—We depend on third-party suppliers for the development and supply of key raw materials and components for our energy storage products. We also depend on vendors for the shipping of our energy storage products. Quality issues or delays in our supply or delivery chain and shipments could harm our ability to manufacture,

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supply and commercialize our energy storage products.”). As a result, our quarterly results of operations are difficult to predict and may fluctuate significantly in the future.

We currently are and in the foreseeable future will be significantly dependent on a limited number of products.

We currently are and in the foreseeable future will continue to be significantly dependent on revenue generated from our newly launched Energy Base product and the servicing thereof while our core component technology productization and future product offerings are under development. Given that our business currently depends on a limited number of products to the extent our products are not well-received by the market, our sales volume, business, financial condition and results of operations would be materially and adversely affected.

Our planned expansion into new geographic markets or new product lines or services could subject us to additional business, financial, and competitive risks.

We have entered into contracts and other agreements to sell our products in a number of different geographic markets, including the United States, Europe (European Union (“EU”) and non-EU), and Australia. We have in the past, and may in the future, evaluate opportunities to expand into new geographic markets and introduce new product offerings and services that are a natural extension of our existing business. For example, we are launching our Energy Base product and are actively bidding on projects for daily cycling applications in the 12 to 24 hour long duration storage market to serve emerging AI/data center driven load needs and to firm baseload renewable production; however, there is no assurance that we will be able to secure any contracts for, or derive any revenue from, the installation of energy storage systems for applications in the 12 to 24 hour long duration storage market. We also may from time to time engage in acquisitions of businesses or product lines with the potential to strengthen our market position, enable us to enter attractive markets, expand our technological capabilities, or provide synergy opportunities.

Our success operating in these new geographic or product markets, or in operating any acquired business, will depend on a number of factors, including our ability to develop solutions to address the requirements of the electric utility industry and other applicable regulatory bodies, renewable energy project developers and owners, and C&I end users, our timely qualification and certification of new products, our ability to manage increased manufacturing capacity and production, and our ability to identify and integrate any acquired businesses.

Further, any additional markets that we may enter could have different characteristics from the markets in which we currently sell products, and our success will depend on our ability to adapt properly to these differences. These differences may include regulatory requirements, including tax laws, trade laws, foreign direct investment review regimes, labor regulations, tariffs, export quotas, customs duties, or other trade restrictions, limited or unfavorable intellectual property protection, international, political or economic conditions, restrictions on the repatriation of earnings, longer sales cycles, warranty expectations, product return policies and cost, certifications, and performance and compatibility requirements. In addition, expanding into new geographic markets will increase our exposure to presently existing and new risks, such as fluctuations in the value of foreign currencies and difficulties and increased expenses in complying with United States and foreign laws, regulations and trade standards, including the Foreign Corrupt Practices Act of 1977, as amended (the “FCPA”).

Failure to develop and introduce new products successfully into the market, to successfully integrate acquired businesses or to otherwise manage the risks and challenges associated with our potential expansion into new product and geographic markets, could adversely affect our revenues and our ability to sustain profitability.

If we fail to maintain effective control over financial reporting, our ability to accurately and timely report our financial results could be adversely affected.

As a public company, we are required to comply with the SEC’s rules implementing Sections 302 and 404 of the Sarbanes-Oxley Act of 2002 (the “Sarbanes-Oxley Act”), which requires management to certify financial and other information in our quarterly and annual reports and to provide an annual management report on the effectiveness of controls over financial reporting (see “Part II—Item 9A. Controls and Procedures”). When evaluating our internal control over financial reporting, we have previously, and may in the future identify material weaknesses that we may not be able to remediate in time to meet the applicable deadline for compliance with the requirements of Section 404. If we are unable to identify and remediate material weaknesses, which may be more challenging as the recent furlough included employees from our accounting department, it could result in material misstatements to our annual or interim financial statements that might not be prevented or detected on a timely basis or result in delayed filings of required periodic reports. If we are unable to assert that our internal control over financial reporting is effective, investors may lose confidence in the accuracy and completeness of our financial reports, the market price of our common stock could be adversely affected and we could become subject to litigation or investigations by the NYSE, the SEC, or other regulatory authorities, which could require additional financial and management resources.

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Although we review and evaluate our internal control systems on a regular basis, we cannot provide any assurances that the measures that we have taken will be sufficient to prevent material weaknesses and control deficiencies from occurring. We also cannot assure you that we have identified all of our existing material weaknesses. If remediation measures are required, they may be time consuming, costly, and might place significant demands on our financial and operational resources.

As deployment of our energy storage products increases, we will undertake corresponding warranty obligations and our warranty obligations may be significant. If our energy storage products do not operate successfully in the field or if we are unable to manage our warranty costs, our business and ability to generate revenue and achieve profitability could fail.

We have experienced quality issues in the field and our products may contain undetected errors or defects, especially when first introduced or when new generations of products are released. Errors, defects, or poor performance can arise due to design flaws, defects in raw materials or components or manufacturing difficulties, which can affect the quality of our products. Any actual or perceived errors, defects, or poor performance in our products could result in repair costs or the replacement or recall of our products, shipment delays, rejection of our products, damage to our reputation, lost revenue, diversion of our personnel from our operational efforts, and increases in customer service and support costs, all of which could have a material adverse effect on our business, financial condition, and results of operations.

Furthermore, defective components may give rise to warranty, indemnity, or environmental or product liability claims against us that exceed any revenue or profit we receive from the affected products. Our product generally comes with an initial one-year manufacturing warranty. We also offer customers an extended performance warranty at an additional cost to the customer. For extended warranties, this may require system augmentation or replacements, which may need to be provided at no additional charge beyond the price of the extended warranty paid by such customer.

While we have accrued reserves for warranty claims, our estimated warranty costs for previously sold products may change to the extent future products are not compatible with earlier generation products under warranty. Our warranty accruals are based on various assumptions, which are based on a short operating history. As a result, these assumptions could prove to be materially different from the actual performance of our systems, causing us to incur substantial unanticipated expenses to repair or replace defective products in the future or to compensate customers for defective products. Our failure to accurately predict future claims could result in unexpected volatility in, and have a material adverse effect on, our financial condition.

Defects or performance problems in our products could result in loss of customers, reputational damage, and decreased revenue, and we may face warranty, indemnity, and product liability claims that may arise from defective products.

We may become subject to product liability claims, even those without merit due to product tampering or operation and maintenance in violation of operating manuals, which could harm our business, financial condition and results of operations. We face inherent risk of exposure to claims in the event our batteries do not perform as expected or malfunction resulting in personal injury or death. Our risks in this area are particularly pronounced given our products have not yet been commercially tested at scale or mass produced. Although we seek to limit our liability, a product liability claim brought against us, even if unsuccessful, would likely be time consuming, costly to defend, and may hurt our reputation in the marketplace. A successful product liability claim against us could require us to pay a substantial monetary award. Moreover, a product liability claim could generate substantial negative publicity about our products and business and inhibit or prevent commercialization of other future battery candidates, which would have a material adverse effect on our brand, business, prospects and operating results. Any insurance coverage might not be sufficient to cover all potential product liability claims. Any lawsuit seeking significant monetary damages either in excess of our coverage, or outside of our coverage, may have a material adverse effect on our reputation, business and financial condition. We may not be able to secure additional product liability insurance coverage on commercially acceptable terms or at reasonable costs when needed, particularly if we do face liability for our products and are forced to make a claim under our policy.

In addition, as we grow our manufacturing volume, the chance of manufacturing defects could increase. We may be unable to correct manufacturing defects or other failures of our components and the products in which they are incorporated in a manner satisfactory to our customers, which could adversely affect customer satisfaction, market acceptance and our business reputation.

Third parties might attempt to gain unauthorized access to our network or seek to compromise our products and services.

Our business is dependent on the security and efficacy of our networks and computer and data management systems. For example, our products deployed in the field are connected to and controlled and monitored by our centralized remote monitoring service, and we rely on our internal computer networks for many of the systems we use to operate our business generally. We have experienced and may in the future face attempts by others to gain unauthorized access through the

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internet or otherwise or to introduce malicious software to our IT systems. We or our products may be a target of computer hackers, organizations or malicious attackers who attempt to:

•gain access to our network or products or networks of our customers;

•steal proprietary information related to our business, products, employees, and customers; or

•interrupt our systems or those of our customers.

We have encountered and in the future may again encounter attempts at gaining unauthorized access to our network. We routinely run security checks to detect and investigate unauthorized attempts and attacks against our network and products of which we become aware, and to prevent their recurrence where practicable through changes to our internal processes and tools and/or changes to our products, we remain potentially vulnerable to additional known or unknown threats. In addition to intentional security breaches, the integrity and confidentiality of company and customer data and our intellectual property may be compromised as a result of human error, including errors, omissions, or misconduct by employees or contractors, product defects, or technological failures. Different geographic markets may have different regulations regarding data protection, raising potential compliance risks. We utilize third-party contractors to perform certain functions for us, and they face security risks similar to us. Further, retaliatory acts by Russia in response to Western sanctions could include cyber attacks that could disrupt the economy more generally or that could also impact our operations directly or indirectly.

Any failure or perceived failure by us or our service providers to prevent information security breaches or other incidents or system disruptions, or any compromise of security that results in or is perceived or reported to result in unauthorized access to, or loss, theft, alteration, release or transfer of, our information, or any personal information, confidential information, or other data could result in loss or theft of proprietary or sensitive data and intellectual property, could harm our reputation and competitive position and could expose us to legal claims, regulatory investigations and proceedings, and fines, penalties, and other liability. Any such actual or perceived security breach, incident or system disruption could also divert the efforts of our personnel, and could require us to incur significant costs and operational consequences in connection with investigating, remediating, eliminating and putting in place additional tools, devices, policies, and other measures designed to prevent actual or perceived security breaches and other incidents and system disruptions, and in, for example, rebuilding internal systems, reduced inventory value, providing modifications to our products and services, defending against claims and litigation, responding to regulatory inquiries or actions, paying damages, or taking other remedial steps with respect to third parties. Moreover, we could be required or otherwise find it appropriate to expend significant capital and other resources to respond to, notify third parties of, and otherwise address the incident or breach and its root cause, and to notify individuals, regulatory authorities and others of security breaches involving certain types of data.

Further, we cannot assure that any limitations of liability provisions in our current or future contracts that may be applicable would be enforceable or adequate or would otherwise protect us from any liabilities or damages with respect to any particular claim relating to a security breach or other security-related matter. We also cannot be sure that our existing insurance coverage will continue to be available on acceptable terms or will be available in sufficient amounts to cover claims related to a security breach or incident, or that the insurer will not deny coverage as to any future claim. The successful assertion of claims against us that exceed available insurance coverage, or the occurrence of changes in our insurance policies, including premium increases or the imposition of large deductible or co-insurance requirements, could have a material adverse effect on our business, including our financial condition, operating results, and reputation.

The failure or breach of our IT systems could affect our sales and operations.

The availability and effectiveness of our energy storage products and our ability to conduct our business and operations, depend on the continued operation of IT and communications systems, some of which we have yet to develop or otherwise obtain the ability to use. Systems used in our business, as well as systems used by third parties on which we rely, will be vulnerable to damage or interruption caused by power outages, climate change and natural disasters, interruptions or vulnerabilities related to the integration of artificial intelligence, and other factors beyond our control or which we do not presently anticipate, including technical defects or errors. Such systems could also be subject to break-ins, sabotage and intentional acts of vandalism, as well as disruptions and security incidents as a result of non-technical issues, including intentional or inadvertent acts or omissions by employees, service providers, or others. We have experienced and in the future expect to face significant challenges with respect to information security and maintaining the security and integrity of our systems and other systems used in our business, as well as with respect to the data stored on or processed by these systems. We also anticipate storing and otherwise processing confidential business information of ourselves and third parties, as well as personal information and other data. Advances in technology, an increased level of sophistication and expertise of hackers, and new discoveries in the field of cryptography can result in a compromise or breach of the systems used in our business or of security measures used in our business to protect confidential information, personal information,

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and other sensitive data, such as data that is subject to export control regulations and controlled unclassified information that is subject to other federal regulations. We may be a target for attacks by state-sponsored actors and others designed to disrupt our operations or to attempt to gain access to our systems or to data that is processed or maintained in our business.

We use outsourced service providers to help provide certain services. For example, we utilize email and collaboration tools and other third-party services and service providers that store or otherwise process information, including personal information and confidential business information, on our behalf. Any such outsourced service providers face similar security and system disruption risks as us. We are at risk for interruptions, outages and breaches of our and our outsourced vendors’ and service providers’ operational systems and security systems, our products’ and services’ integrated software and technology, and customer data that we or our third-party service providers process. These may be caused by, among other causes, physical theft, viruses or other malicious code, denial or degradation of service attacks, ransomware, social engineering schemes, and insider theft or misuse. While we take steps to review security protections of services provided to us, there can be no guarantee that a failure or breach of such systems will not occur or be perceived to occur. If such failures were to occur, we may not be able to sufficiently recover to avoid the loss of data or any adverse impact on our operations that are dependent on such IT systems. This could result in lost sales as we may not be able to meet the demands for our product, and other harm to our business and results of operations. Further, some of the systems used in our business will not be fully redundant, and our disaster recovery planning cannot account for all eventualities. Security breaches or incidents or other damage to or disruptions to any data centers or other systems used in our business have in the past resulted in interruptions and could in the future result in lengthy interruptions in our service and may adversely affect our business, prospects, financial condition and operating results.

Furthermore, because our IT systems are essential for the exchange of information both internally and in communicating with third parties, including our suppliers and manufacturers, security breaches or other cybersecurity incidents could lead to unauthorized acquisition or unauthorized release of sensitive, confidential or personal data or information, improper use of our systems, or unauthorized access, use, disclosure, modification or destruction of information or defective products. Our IT systems also help us produce financial information. We have not, as of the date of this report, experienced a cybersecurity incident or cybersecurity risk that we have determined has had a material adverse effect on our business. However, any disruption, security breach, or other incident could impact our ability to produce timely and accurate financial information needed for compliance, audit, and reporting purposes. If any such security breaches or incidents were to continue, our ability to communicate both internally and with third parties and other aspects of our operations may be negatively impacted. For example, on November 1, 2025, we became aware of a cybersecurity incident involving unauthorized access which resulted in the non-availability of certain systems and a limited volume of data. We promptly activated our cybersecurity incident response protocols, initiated an investigation, and retained external cybersecurity experts to assist in our response. As of the date of this report, we have completed the investigation and remediation and identified no material impacts on the operations or results of the Company.

Significant capital and other resources may be required in efforts to protect against security breaches, incidents, and system disruptions, or to alleviate problems caused by actual or suspected security breaches and other incidents and system disruptions. The resources required may increase over time as the methods used by hackers and others engaged in online criminal activities and otherwise seeking to obtain unauthorized access to systems or data, and to disrupt systems, are increasingly sophisticated and constantly evolving. In addition, laws, regulations, government guidance, and industry standards and practices in the United States and elsewhere are rapidly evolving to combat these threats. We may face increased compliance burdens regarding such requirements with regulators and customers regarding our products and services and also incur additional costs for oversight and monitoring of our supply chain. We also cannot be certain that these systems, networks, and other infrastructure or technology upon which we rely, including those of our third-party suppliers or service providers, will be effectively implemented, maintained or expanded as planned, or will be free from bugs, defects, errors, vulnerabilities, viruses, or malicious code. We may be required to expend significant resources to make corrections or to remediate issues that are identified or to find alternative sources. Any of these circumstances potentially could have a negative impact on our business, prospects, financial condition and operating results.

We may not be able to identify or complete transactions with attractive acquisition candidates. Future acquisitions may result in significant transaction expenses and we may incur significant costs.

We may from time to time selectively pursue on an opportunistic basis acquisitions of additional businesses that complement our existing business and footprint. The success of any such growth strategy would depend, in part, on selecting strategic acquisition candidates at attractive prices and effectively integrating their businesses into our own, including with respect to financial reporting and regulatory matters. There can be no assurance that we will be able to identify attractive acquisition candidates or complete the acquisition of any identified candidates at favorable prices and upon advantageous terms and conditions, including financing alternatives. In addition, general economic conditions or unfavorable capital and credit markets could affect the timing and extent to which we can successfully acquire new businesses, which could limit our revenues and profitability.

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Our facilities or operations could be damaged or adversely affected as a result of natural disasters and other catastrophic events.

Our facilities or operations could be adversely affected by events outside of our control, such as natural disasters, wars, health epidemics and other calamities. We cannot assure you that any backup systems will be adequate to protect our facilities or operations from the effects of fire, floods, typhoons, earthquakes, power loss, telecommunications failures, break-ins, war, riots, terrorist attacks or similar events. Any health epidemics, outbreaks of contagious diseases and other adverse public health developments in countries where we and our suppliers operate could have a material adverse effect on our business, financial condition and results of operations. Any of the foregoing events may give rise to interruptions, breakdowns, system failures, technology platform failures or internet failures, which could cause the loss or corruption of data or malfunctions of software or hardware as well as adversely affect our ability to provide services.

We may not have sufficient insurance coverage to cover business continuity.

A sustained or repeated interruption in the manufacturing of our products due to labor shortage, fire, flood, war, pandemic, natural disasters, regulatory requirements, and similar unforeseen events beyond our control may interfere with our ability to manufacture our products and fulfill customers’ demands in a timely manner, and make it difficult, or in certain cases, impossible for us to continue our business for a substantial period of time. Failure to manufacture our products and meet customer demands would impair our ability to generate revenues which would adversely affect our financial results. We currently do not have a formal disaster recovery or business continuity plan in place and any disaster recovery and business continuity plans that we may put in place may prove inadequate in the event of a serious disaster or similar event. As part of our risk management, we maintain insurance coverage for our business. However, we cannot assure you that the amount of insurance will be sufficient to satisfy any damages or losses we may incur. If our insurance coverage is not sufficient, we may incur substantial expenses, which, could have a material adverse effect on our business.

Changes in the global trade environment, including the imposition or escalation of import tariffs, could adversely affect the amount or timing of our revenues, results of operations or cash flows.

While our current supply chain is largely domestic, it includes Chinese sources for various parts. Escalating trade tensions, particularly between the United States and China have led to increased tariffs and trade restrictions, including current and recent tariffs applicable to certain electronic materials and components of our products. These tariffs include Section 301 tariffs that the U.S. Trade Representative has imposed on certain imports from China since 2018, the additional fentanyl-related tariff on most Chinese-origin goods as implemented by the U.S. government between February 2025 and February 2026, and the reciprocal tariffs implemented by the U.S. government between April 2025 and February 2026. Further, the United States has implemented additional global sector-specific Section 232 tariffs on various items, including certain steel and aluminum products, automobiles and automotive components, and copper products. The U.S. government has announced intentions to place additional future tariffs on various pharmaceutical, semiconductor, and consumer electronic products. In addition, fentanyl-related tariffs on various imports from Canada and Mexico were implemented with respect to non-USMCA-qualifying goods between March 2025 and February 2026. After the Supreme Court held that the fentanyl-related and reciprocal tariffs implemented under the International Emergency Economic Powers Act were ultra vires, the United States ceased collection of these tariffs and implemented a global, 10 percent tariff on many of the same items under authorities provided in Section 122 of the Trade Act of 1974. It is unclear whether or how the U.S. government will issue refunds for previous payments made in connection with the fentanyl-related and reciprocal tariffs and whether or how U.S. tariff policy might change in the future or how other countries may retaliate or respond to changing U.S. tariff policies. For example, additional tariffs may be forthcoming under Section 232, Section 301, Section 122, Section 338, and/or other legal authorities.

Current and recent tariffs and the possibility of additional tariffs in the future have created uncertainty, particularly if we are not able to second source parts from alternative vendors. There can be no guarantee that these developments will not negatively impact the price of the positive electrode used in our products. Additionally, existing, future, or potential tariffs may negatively affect key customers and suppliers, and other supply chain partners. Such outcomes could adversely affect the amount or timing of our revenues, results of operations or cash flows, and cause sales volatility, price fluctuations or supply shortages or cause our customers to advance or delay their purchase of our products.

We are in the process of qualifying alternative sources but anticipate it will take time before alternate sources are qualified for every component. Depending on the outcome of the tariffs that the Trump administration has implemented, previously implemented, and may eventually implement on additional products and/or countries, our ability to secure alternative sources of components may be further limited in the future. In addition, such sources may charge a higher cost than our current suppliers, which would negatively impact our results of operations. There is no guarantee that we will be able to identify alternate suppliers that meet our quality, volume and price requirements. Failure to meet these requirements could result in supply disruptions and increased costs. It is difficult to predict what further trade-related actions governments may

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take, which may include additional or increased tariffs and trade restrictions, and we may be unable to react to such actions quickly, cheaply or effectively, which could result in supply shortages and increased costs.

We could be subject to foreign exchange risk.

Our international sales are typically denominated in U.S. dollars. As a result, we will not have significant direct exposure to currency valuation exchange rate fluctuations. However, because our products are sold internationally, our products may be at a price disadvantage as compared with other non-U.S. suppliers if the U.S. dollar appreciates relative to other major foreign currencies. This could lead to our having to lower prices or our struggling to compete for international customers. Consequently, currency fluctuations, in particular, a strengthening of the U.S. dollar, could adversely affect the competitiveness of our products in international markets.

We may be required to take write-downs or write-offs, restructuring and impairment or other charges that could have a significant negative effect on our financial condition, results of operations and stock price, which could cause you to lose some or all of your investment.

Unexpected risks may arise that cause us to write-down or write-off assets, restructure our operations, or incur impairment or other charges that could result in losses. Even though these charges may be non-cash items and not have an immediate impact on our liquidity, the fact that we report charges of this nature could contribute to negative market perceptions about us or our securities. In addition, charges of this nature may cause us to violate net worth or other covenants to which we may be subject. Accordingly, our stockholders could suffer a reduction in the value of their shares.

Our results of operations could vary as a result of changes to our accounting policies or the methods, estimates and judgments we use in applying our accounting policies.

The estimates and judgments we use in applying our accounting policies have a significant impact on our results of operations. Such methods, estimates and judgments are, by their nature, subject to substantial risks, uncertainties and assumptions, and factors may arise over time that could lead us to reevaluate our methods, estimates and judgments.

Management regularly evaluates its estimates such as for service agreements, loss accruals, warranty, performance guarantees, liquidated damages and inventory valuation allowances. Changes in those estimates and judgments could significantly affect our financial condition and results of operations. We will also adopt changes required by the Financial Accounting Standards Board and the SEC.

The requirements of being a public company may strain our resources and divert management’s attention.

As a public company, we are subject to the reporting requirements of the Exchange Act, the Sarbanes-Oxley Act, the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010, as well as rules adopted, and to be adopted, by the SEC and the NYSE. Compliance with such public company requirements is costly, time-consuming and complex. We expect management and other personnel to continue to devote a substantial amount of time and resources to these compliance initiatives. We cannot predict or estimate the amount or timing of additional costs we may incur to respond to these requirements as they continue to evolve over time. The impact of these requirements could also make it more difficult for us to attract and retain qualified persons to serve on our board of directors or as executive officers.

In addition, we may not have adequate personnel with the appropriate level of knowledge, experience and training in the accounting policies, practices or internal controls over financial reporting required of public companies in the United States. The development and implementation of the standards and controls necessary for us to achieve the level of accounting standards required of a public company in the United States may require costs greater than expected. It is possible that we will be required to further expand our employee base and hire additional employees to support our operations as a public company, which will increase our operating costs in future periods.

Moreover, our efforts to comply with new and changing laws and regulations related to public disclosure and corporate governance have resulted in increased general and administrative expenses and a diversion of management time and attention. Because these laws, regulations and standards are subject to varying interpretations, their application in practice may evolve over time as new guidance becomes available. This evolution may result in continuing uncertainty regarding compliance matters and additional costs necessitated by ongoing revisions to our disclosure and governance practices. If we fail to address and comply with these regulations and any subsequent changes, we may be subject to penalties and our business may be harmed.

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We may engage in transactions with related parties and such transactions present possible conflicts of interest that could have an adverse effect on us.

We have entered into transactions, and may in the future enter into further transactions with related parties. Related-party transactions create the possibility of conflicts of interest with regard to management, including that:

•we may enter into contracts between us, on the one hand, and related parties, on the other, that are not as a result of arm’s-length transactions;

•our executive officers and directors that hold positions of responsibility with related parties may be aware of certain business opportunities that are appropriate for presentation to us as well as to such other related parties and may present such business opportunities to such other parties; and

•our executive officers and directors that hold positions of responsibility with related parties may have significant duties with, and spend significant time serving, other entities and may have conflicts of interest in allocating time.

Such conflicts could cause such executive officer or director to seek to advance his or her economic interests or the economic interests of certain related parties above ours. Further, the appearance of conflicts of interest created by related-party transactions could impair the confidence of our investors. Our audit committee and our board of directors regularly review these transactions. Notwithstanding this, it is possible that a conflict of interest could have a material adverse effect on our business, financial condition and results of operations.

Our relationships with related parties, SBE, an affiliate of SoftBank Group Corp., and Honeywell, are subject to various risks which could adversely affect our business and future prospects. There are no assurances that we will be able to commercialize iron flow batteries from our joint development relationship with such parties. In addition, neither SBE nor Honeywell has any obligation to order any energy storage products from us under the agreements with such business partners, including at any price point.

In April 2021, we signed a framework agreement with SBE to supply our energy storage products to SBE in support of its market activities. Under this agreement, we have made various commitments to meet SBE’s potential need for our energy storage products and are obligated to reserve a certain percentage of our manufacturing capacity to meet SBE’s future needs, subject to periodic reviews of its firm and anticipated orders, which may negate those capacity reservations if no firm demand is realized. However, SBE is under no obligation to place any firm orders with us at any price point, and any future orders may be subject to future pricing or other commercial or technical negotiations, which we may not be able to satisfy, resulting in a diminished potential value of this relationship to us. To date, no orders have been placed under the framework agreement.

On September 21, 2023, we signed a Supply Agreement with UOP LLC (“UOP”), an affiliate of Honeywell International Inc. (“Honeywell”), pursuant to which UOP may purchase equipment supplied by us, and we agreed to issue additional warrants to purchase common stock to UOP, consisting of (i) an initial Performance Warrant to issue up to 51,717 shares of common stock, issued on September 21, 2023 in exchange for a prepayment of equipment by UOP in the amount of $15 million, and (ii) additional Performance Warrants (not to exceed an aggregate value of $15 million based on target purchase amounts of up to $300 million by 2030) to be issued on an annual basis for the five-year period beginning in 2026, based on UOP’s purchase of additional equipment after execution of the Supply Agreement. On September 21, 2023, we and UOP also entered into a Joint Development Agreement, pursuant to which we and UOP have agreed to work together to collaborate and engage in certain research and development activities generally related to flow battery technology, and a Patent License Agreement, pursuant to which UOP will license certain patent rights to us. However, Honeywell is under no obligation to place any additional firm orders with us at any price point, and any future orders may be subject to future pricing or other commercial or technical negotiations, which we may not be able to satisfy, resulting in a diminished potential value of this relationship to us. In addition, while activities under the Joint Development Agreement have commenced, we and Honeywell may not be able to agree on future activities and endeavors to pursue under the Joint Development Agreement, activities under the Joint Development Agreement may not be successful, or the Patent License Agreement may have limited value to us.

SBE, Honeywell, and any other business partners in the future, may have economic, business or legal interests or goals that are inconsistent with our interests or goals. Any disagreements with our current or other future business partners may impede our ability to maximize the benefits of these partnerships and slow the commercialization of our iron flow batteries. Future commercial or strategic counterparties may require us, among other things, to pay certain costs or to make certain capital investments or to seek their consent to take certain actions. In addition, if our business partners are unable or unwilling to meet sourcing, development, or other obligations under our partnership arrangements, we may be required to fulfill those obligations alone. These factors could result in a material adverse effect on our business and financial results.

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The execution of our strategy to expand into new markets through strategic partnerships, joint ventures and licensing arrangements is in a very early stage and is also subject to various risks which could adversely affect our business and future prospects.

We may enter into strategic partnerships, joint ventures and licensing arrangements to expand our business and enter into new markets. However, there is no assurance that we will be able to consummate any such arrangements as contemplated to commercialize our energy storage products. There is also no assurance that we will be able to realize the benefits of any such arrangements even if we do enter into such strategic partnerships, joint ventures and licensing arrangements and there is always a risk that either party may be unable to comply with its delivery, payment, or other obligations under any such arrangement. The occurrence of any such risks may result in diminished potential value of these types of relationships to us. For example, in 2022 we entered into a strategic partnership with Energy Storage Industries Asia Pacific (“ESI”) and a framework agreement with Sacramento Municipal Utility District (“SMUD”). We delivered Energy Warehouse systems to ESI from 2022 through early 2025 to fulfill their orders. We agreed to move forward separately from our 2022 agreement in late 2025 and recognize the opportunity to work together again in the future, although ESI is under no obligation to place additional orders with us. We made the first delivery of our systems to SMUD during the second quarter of 2023, but the task authorization supporting the Energy Warehouse pilot and the next phase order of our Energy Center expired on December 31, 2024, and while we are in discussions for future task authorizations, SMUD is under no obligation to continue the task authorization or place additional orders with us.

Any future strategic partnerships, joint ventures or licensing arrangements may require us, among other things, to pay certain costs, make certain capital investments or to seek the partner’s consent to take certain actions. In addition, if a partner is unable or unwilling to meet its economic or other obligations under the respective arrangements, we may be required to either fulfill those obligations alone to ensure the ongoing success of, or to dissolve and liquidate, the partnership, joint venture or licensing arrangement. These factors could result in a material adverse effect on our business, prospects and financial results.

Our review of commercial and strategic transactions may be disruptive to our business and may not be successful.

We continue to investigate and pursue commercial or financial transactions, which could include, among other things, divestitures, a merger or sale, joint ventures, partnerships and financings. Exploring commercial and financial transactions may create a significant distraction for our management team and board of directors and require us to expend significant time and resources and incur expenses for advisors. Moreover, the review and consideration of such commercial and financial transactions may disrupt our business by causing uncertainty among current and potential employees, suppliers, customers and investors. The selection and execution of a commercial or financial transaction may lead to similar disruptions, and parties advocating for alternatives not selected may solicit support for such other alternatives, causing further disruption.

Despite our plan to devote significant efforts to identify and evaluate potential commercial and financial transactions, the process may not result in any definitive offer to consummate such a transaction, or, if we receive such a definitive offer, the terms may not be as favorable as anticipated or may not result in the execution or approval of a definitive agreement. Even if we enter into a definitive agreement, we may not be successful in completing a transaction or, if we complete such a transaction, it may not enhance stockholder value or deliver expected benefits.

If we do not successfully identify a viable commercial or financial transaction, or consummate such a transaction, or if we are unable to raise sufficient capital to fund our operations, our board of directors may determine that the liquidation of our assets, wind-down, dissolution, or other restructuring of our business is the best method to seek to maximize value. In such an event, the amount of cash available for distribution to our stockholders, if any, would depend on many factors, including the costs and timing of such liquidation, the market for our assets, our cash balance, the amount of cash that would need to be reserved for commitments and contingent liabilities, and the amount and relative priority of our liabilities.

Accordingly, holders of our shares and warrants could lose all or a significant portion of their investment in the event of a liquidation of our assets, wind-down, dissolution, or other restructuring of our business.

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Risks Related to Regulatory, Environmental and Legal Issues

We may face regulatory challenges to or limitations on our ability to sell our products directly in certain markets. Expanding operations internationally could expose us to additional risks.

While we intend to continue to sell our products across the United States both directly and through third parties, our ability to continue such sales may be affected by future limitations, either directly to the ability to sell energy storage or by broader regulation related to the sales and operation of distributed energy resources, which could have an impact on our ability to sell our products to the market.

Although we currently primarily operate in the United States, we continue to expand our business internationally. Any expansion internationally could subject our business to risks associated with international operations, including legal and regulatory requirements, political uncertainty and social, environmental and economic conditions in numerous jurisdictions, over which we have little control and which are inherently unpredictable. Our operations in such jurisdictions, particularly as a company based in the United States, create risks relating to conforming our products to regulatory and safety requirements and charging and other electric infrastructures; organizing local operating entities; establishing, staffing and managing foreign business locations; attracting local customers; navigating foreign government taxes, regulations and permit requirements; enforceability of our contractual rights; trade restrictions, export controls, foreign direct investment review regimes, customs regulations, tariffs and price or exchange controls; and preferences in foreign nations for domestically manufactured products. Such conditions may increase our costs and tax liabilities, impact our ability to sell and service our products and require significant management attention, and may harm our business if we are unable to manage them effectively.

In addition, there may be laws in international jurisdictions we have not yet entered, laws we are unaware of in jurisdictions we have entered, or changes to laws in jurisdictions we have entered that may affect or restrict our sales or other business practices. Even for those jurisdictions we have analyzed, the laws in this area can be complex, difficult to interpret and may change over time. Continued regulatory limitations and other obstacles interfering with our ability to sell our energy storage products may harm our business, financial condition and results of operations. Additionally, any regulation that affects the sale or operations of distributed energy resources could diminish the real or perceived value of our energy storage solutions in those markets. As a result of these risks, any potential future international expansion efforts that we may undertake may not be successful.

Our customers may be required to obtain environmental, health and safety or other certifications in order to install our products. If our customers are unable to obtain the necessary certifications, we will not be able to install our products, which would negatively impact our revenues.

While our engineering team has worked closely with the CSA Group, Intertek, UL and Technischer Überwachungsverein certification agencies to obtain certifications of our flow battery products under all applicable safety standards, there is no guarantee that such certifications will continue to be obtained or that our batteries will be certificate compliant. From our prior certifications, we have expanded our flow battery product certification to the European Conformity marking in the European Union and intend to expand to other international standards such as the International Electrotechnical Commission (“IEC”). Failure to comply with IEC standards may impact our revenues, as compliance is required by some of our customers.

We are subject to multiple U.S. federal, state, local and other applicable regulations. Changes in applicable law, regulations or requirements, or our material failure to comply with any of them, can increase our costs and have other negative impacts on our business.

Applicable laws and requirements address multiple aspects of our operations, such as worker safety, consumer rights, privacy, cybersecurity, employee benefits and more, and can often have different requirements in different jurisdictions. Changes in these requirements, or any material failure to comply with them, could increase our costs, affect our reputation, result in claims, litigation, and regulatory investigations or other proceedings, which may result in fines, penalties, and other liabilities, and which may limit our business, drain management’s time and attention or otherwise, and generally impact our operations in adverse ways.

We are subject to requirements relating to environmental and safety regulations and environmental remediation matters which could adversely affect our business, results of operation and reputation.

We are subject to numerous federal, state and local environmental laws and regulations governing, among other things, solid and hazardous waste storage, treatment and disposal, and remediation of releases of hazardous materials. There are significant capital, operating and other costs associated with compliance with these environmental laws and regulations. Environmental laws and regulations may become more stringent in the future, which could increase costs of compliance or require us to manufacture with alternative technologies and materials.

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Federal, state and local authorities also regulate a variety of matters, including, but not limited to, health, safety and permitting in addition to the environmental matters discussed above. Site inspections, new legislation, or new regulations may trigger new facility requirements, process controls, reporting requirements, or material changes to our operations, resulting in significant increases to the cost of production.

Our manufacturing process involves hazards such as but not limited to hazardous materials, machines with moving parts, and high voltage and/or high current electrical systems typical of large manufacturing equipment and related safety incidents.

We have had, and in the future may have further, environmental or safety incidents that damage machinery or product, slow or stop production or field operations, harm employees or result in leakage of electrolyte. Consequences may include litigation, regulation, fines, increased insurance premiums, decisions or mandates to temporarily halt production or field operations, workers’ compensation claims, expenses related to site remediation or other actions that impact our brand and reputation, customer’s willingness to place future orders, our operating results and financial condition, our ability to operate, and our future prospects.

We may be exposed to delays, limitations and risks related to the environmental permits and other operating permits required to operate our products.

Operation of our manufacturing facilities requires land use and environmental permits and other operating permits from federal, state and local government entities. New permits may be required to carry out and perform our current plans and operations at our existing facility, including with respect to manufacturing, treatment, and storage of our electrolyte, and we may require additional environmental, wastewater and land use permits for the commercial operation of any future manufacturing facilities. Delays, denials or restrictions on any of the applications for or assignment of the permits to operate our manufacturing facilities could adversely affect our ability to execute on our business plans and objectives.

We may collect and process certain information about our customers and about individuals and will be subject to various laws and regulations relating to privacy, data protection and cybersecurity.

We may collect and process certain battery data required for performance monitoring, safety and serviceability. This information is transmitted to our control center and stored. Such data currently is limited to battery operational and safety parameters. Additionally, we collect and otherwise process other data relating to individuals, including business partners, prospects, employees, vendors, and contractors. Our handling of data relating to individuals is subject to a variety of laws and regulations relating to privacy, data protection and cybersecurity, and we may become subject to additional obligations, including contractual obligations, relating to our maintenance and other processing of this data, and new or modified laws or regulations, such as regulations pertaining to controlled unclassified information or data that is subject to export control laws. Laws, regulations, and other actual and potential obligations relating to privacy, data protection, and cybersecurity are evolving rapidly, and we expect to potentially be subject to new laws and regulations, or new interpretations of laws and regulations, in the future in various jurisdictions. These laws, regulations, and other obligations, and changes in their interpretation, could require us to modify our operations and practices, restrict our activities, and increase our costs. Further, these laws, regulations, and other obligations are complex and compliance with them can be difficult. It is possible that these laws, regulations, and other obligations may be inconsistent with one another or be interpreted or asserted to be inconsistent with our business or practices. We anticipate needing to dedicate substantial resources in order to comply with laws, regulations, and other obligations relating to privacy and cybersecurity. Any actual or alleged failure by us to comply with our privacy policy or any federal, state or international privacy, data protection or cybersecurity laws or regulations or other obligations could result in claims and litigation against us, regulatory investigations and other proceedings, legal liability, fines, damages and other costs. Any actual or alleged failure by any of our vendors or business partners to comply with contractual or legal obligations regarding the protection of information about our customers could carry similar consequences. Should we become subject to additional laws, regulations, or other obligations relating to privacy, data protection or cybersecurity, we may need to undertake compliance efforts that could carry a large cost and could entail substantial time and other resources.

Further, although we take steps to protect the security of our customers’ personal information and other personal information within our control, we may face actual or perceived security breaches, incidents, or other misuses of this information, and many jurisdictions have enacted laws requiring companies to notify individuals, regulatory authorities and others of security breaches involving certain types of data. We may be required to expend significant resources to comply with security breach and incident notification requirements if a third party accesses or acquires such personal information without authorization, if we otherwise experience a security breach or incident or loss or damage of personal information, or if this is perceived to have occurred. Any actual or perceived breach of our network or systems, or those of our vendors or service providers, could result in claims, litigation, and proceedings against us by governmental entities or others, have negative effects on our business and future prospects, including possible fines, penalties and damages, or loss of eligibility

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for government grants and contracts, and could result in reduced demand for our energy storage products and harm to our reputation and brand, resulting in negative impacts to our business, prospects, and financial results.

We could be subject to penalties and other adverse consequences for any violations of the FCPA, and other foreign anti-bribery and anti-corruption laws.

We are subject to the FCPA, the U.S. domestic bribery statute contained in 18 U.S.C. § 201, the United Kingdom Bribery Act 2010, and possibly other anti-bribery and anti-corruption laws in countries outside of the United States in which we conduct our activities. We may have business dealings with customers in certain countries that are high risk for corruption. Anti-corruption and anti-bribery laws have been enforced aggressively in recent years and are interpreted broadly to generally prohibit companies and their employees, agents, representatives, business partners, and third-party intermediaries from authorizing, offering, or providing, directly or indirectly, improper payments or benefits to recipients in the public or private sector.

We sometimes leverage third parties to sell our products and conduct our business abroad. We, our employees, agents, representatives, business partners or third-party intermediaries may have direct or indirect interactions with officials and employees of government agencies or state-owned or affiliated entities and may be held liable for the corrupt or other illegal activities of these employees, agents, representatives, business partners or third-party intermediaries even if we do not explicitly authorize such activities. We cannot assure you that all of our employees and agents will not take actions in violation of applicable law, for which we may be ultimately held responsible. We currently have contracts and may potentially operate in parts of the world that have experienced higher levels of governmental corruption and as we increase our international sales and business, our risks under these laws may increase. In addition, due to the level of regulation in our industry and related energy industries, our entry into certain jurisdictions may require substantial government contact where norms can differ from U.S. standards.

These laws also require that we keep accurate books and records and maintain internal controls and compliance procedures designed to prevent any such actions. While we have policies and procedures to address and to mandate compliance with such laws, we cannot assure you that none of our employees, agents, representatives, business partners or third-party intermediaries will take actions in violation of our policies and applicable law, for which we may be ultimately held responsible.

In the event that we believe, have reason to believe, or are notified that our employees, agents, representatives, business partners, or third-party intermediaries have or may have violated applicable laws, including anti-bribery and anti-corruption laws, we may be required to investigate or have outside counsel investigate the relevant facts and circumstances, and detecting, investigating and resolving actual or alleged violations can be expensive and require significant time and attention from senior management. Any allegation or violation of U.S. federal and state and non-U.S. laws, regulations and policies regarding anti-bribery and anti-corruption could result in substantial fines, sanctions, civil and/or criminal penalties, whistleblower complaints, sanctions, settlements, prosecution, enforcement actions, damages, adverse media coverage, investigations, loss of export privileges, suspension or debarment from government contracts, or other curtailment of operations in the United States or other applicable jurisdictions. In addition, actual or alleged violations could damage our reputation and ability to do business. Any of the foregoing could materially adversely affect our reputation, business, financial condition, prospects and results of operations.

We are subject to governmental export and import controls and economic sanctions programs that could impair our ability to compete in international markets or subject us to liability if we violate these controls.

Our products and services are, or may in the future be, subject to U.S. export control laws and regulations including the Export Administration Regulations (“EAR”) and trade and economic sanctions maintained by the Office of Foreign Assets Control (“OFAC”) and to similar laws and regulations in all other jurisdictions in which we operate. As such, a license may be required to export, re-export or transfer our products and services to certain countries or end-users or for certain end-uses. If we were to fail to comply with such export control laws and regulations or trade and economic sanctions, we could be subject to both civil and criminal penalties, including substantial fines, possible incarceration for employees and managers for willful violations, and the possible loss of our export and/or import privileges. Compliance with the EAR, OFAC sanctions, and other applicable regulatory requirements regarding the import and export of our products or the performance of services, may create delays in the introduction of our products and services in non-U.S. markets, prevent our customers with non-U.S. operations from deploying these products and services throughout their global systems or, in some cases, prevent the export of the products and services to some countries or users altogether. We may enter into agreements with customers and counterparties located in countries subject to list-based OFAC sanctions.

Obtaining the necessary export license for a particular sale or offering may not be possible, may be time-consuming, and may result in the delay or loss of sales opportunities. Further, U.S. export control laws and trade and economic sanctions as well as similar laws and regulations in other jurisdictions prohibit the export of products and services to certain U.S.

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embargoed or sanctioned countries, governments, and persons, as well as for prohibited end-uses. Even though we have taken precautions to ensure that we and our partners comply with all relevant import and export control laws and regulations and sanctions, monitoring and ensuring compliance with these complex laws and regulations is particularly challenging, and any failure by us or our partners to comply with such laws and regulations could have negative consequences for us, including reputational harm, government investigations and penalties.

Any change in domestic or international export or import laws or regulations, economic sanctions, or related legislation, shift in the enforcement or scope of existing export, import, or sanctions laws or regulations, or change in the countries, governments, persons, or technologies targeted by such export, import, or sanctions laws or regulations, could result in decreased use of our products and/or services by, or in our decreased ability to export or sell our products and/or services to, end-customers with international operations.

We may be exposed to various risks related to legal proceedings or claims that could adversely affect our operating results. The nature of our business exposes us to various liability claims, which may exceed the level of our insurance coverage resulting in our not being fully protected.

We have been and may continue to be party to lawsuits in the normal course of our business. Litigation can be expensive, lengthy and disruptive to normal business operations even if the grounds are meritless. Moreover, the results of complex legal proceedings are difficult to predict. Responding to lawsuits brought against us, or legal actions that we may initiate, can be expensive and time-consuming. Unfavorable outcomes from these claims and/or lawsuits could adversely affect our business, financial condition or results of operations, and we could incur substantial monetary liability and/or be required to change our business practices.

Our business may expose us to claims for personal injury, death or property damage resulting from the use of our products or from employee related matters. Additionally, we could be subject to potential litigation associated with compliance with various laws and governmental regulations at the federal, state or local levels, such as those relating to the protection of persons with disabilities, employment, health, safety, security and other regulations under which we operate.

We carry comprehensive insurance, subject to deductibles, at levels we believe are sufficient to cover existing and future claims made during the respective policy periods. However, we may be exposed to multiple claims, and, as a result, could incur significant out-of-pocket costs before reaching the deductible amount, which could adversely affect our financial condition and results of operations. In addition, the cost of such insurance policies may increase significantly upon renewal of those policies as a result of general rate increases for the type of insurance we carry as well as our historical experience and experience in our industry. Although we have not experienced any material losses that were not covered by insurance, our existing or future claims may exceed the coverage level of our insurance, and such insurance may not continue to be available on economically reasonable terms, or at all. If we are required to pay significantly higher premiums for insurance, are not able to maintain insurance coverage at affordable rates or must pay amounts in excess of claims covered by our insurance, then we could experience higher costs that could adversely affect our financial condition and results of operations.

We are subject to certain restrictions and obligations on our business as a result of grants and/or loans received under certain governmental programs and we may be subject to similar or other restrictions to the extent we utilize governmental grants in the future.

Some of our research has been funded by grants from U.S. government agencies. In conjunction with the Advanced Research Projects Agency-Energy grant we received from the Department of Energy, we granted to the United States a non-exclusive, nontransferable, irrevocable, paid-up license to practice or have practiced for or on behalf of the United States inventions related to iron flow technology made within the scope of the grant. When new technologies are developed with U.S. government funding, the government obtains certain rights in any resulting patents and technical data, generally including, at a minimum, a nonexclusive license authorizing the government to use the invention or technical data for noncommercial purposes. U.S. government funding must be disclosed in any resulting patent applications, and our rights in such inventions will normally be subject to government license rights, periodic progress reporting, foreign manufacturing restrictions and march-in rights. Therefore, if we failed to disclose to the Department of Energy an invention made with grant funds that we disclosed to patent counsel or for publication, or if we elect not to retain title to the invention, the United States may request that title to the subject invention be transferred to it.

March-in rights refer to the right of the U.S. government, under certain limited circumstances, to require us to grant a license to technology developed under a government grant to a responsible applicant or, if we refuse, to grant such a license itself. March-in rights can be triggered if the government determines that we have failed to work sufficiently towards achieving practical application of a technology or if action is necessary to alleviate health or safety needs, to meet requirements of federal regulations or to give preference to U.S. industry. If we breach the terms of our grants, the

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government may gain rights to the intellectual property developed in our related research. The government’s rights in our intellectual property may lessen its commercial value, which could adversely affect our performance.

Moreover, we may be adversely affected by government shutdowns. The U.S. government has experienced budgetary shutdowns in the past and may again in the future. In the event of a prolonged government shutdown, or if regulatory agencies experience restrictions on entering into contracts with third parties, there could be a material adverse effect on our business. Further, in our operations as a public company, future government shutdowns could impact our ability to access the public markets and obtain necessary capital in order to properly capitalize and continue our operations.

To the extent we utilize governmental grants in the future, the governmental entities involved may retain certain rights in technology that we develop using such grant money. These rights could restrict our ability to fully capitalize upon the value of this research by reducing total revenues that might otherwise be available since such governmental rights may give the government the right to practice the invention without payment of royalties if we do not comply with applicable requirements. Such grants and other forms of government incentives may also subject us to additional disclosure or reporting requirements.

The reduction, elimination or expiration of government tax credits, subsidies and economic incentives related to renewable energy solutions could reduce demand for our technology and harm our business.

The U.S. federal government and some state and local governments provide incentives to end users and potential purchasers of our energy storage products in the form of rebates, tax credits and other financial incentives, such as system performance payments and payments for renewable energy credits associated with renewable energy generation. We will rely on these governmental rebates, tax credits and other financial incentives to significantly lower the effective price of the energy storage products to our customers in the United States. However, these incentives may expire on a particular date, end when the allocated funding is exhausted, or be reduced or terminated as a matter of regulatory or legislative policy.

Our energy storage products have qualified for tax exemptions, incentives or other customer incentives in many states including California. Some states have utility procurement programs and/or renewable portfolio standards for which our technology is eligible. There is no guarantee that these policies will continue to exist in their current form, or at all. Such state programs may face increased opposition on the U.S. federal, state and local levels in the future. Changes in federal or state programs could reduce demand for our energy storage products, impair sales financing and adversely impact our business results.

On August 16, 2022, the President of the United States signed into law the Inflation Reduction Act of 2022 (the “IRA”), which extended the availability of investment tax credits (“ITCs”) and production tax credits (“PTCs”) and made significant changes to the tax credit regime that applies to solar and energy storage projects. As a result of changes made by the IRA, the ITC for solar generation projects was extended until at least 2033, and expanded to include stand-alone battery storage projects. This expansion provided more certainty on the tax incentives available to stand-alone battery storage projects in the future. Subject to recently enacted legislation discussed below, we believe the IRA will increase demand for our products and services due to the extensions and expansions of various tax credits that are critical for our customers’ economic returns, while also providing more certainty in and visibility into the supply chain for materials and components for energy storage systems. To date, guidance has been released by the Internal Revenue Service (“IRS”) and the U.S. Treasury Department (“Treasury”) to implement many of the IRA’s provisions, including with respect to battery storage projects and domestic content requirements, however there continues to be uncertainty with respect to certain aspects of the IRA, which could cause our customers to delay projects pending further guidance and legislative changes and which could reduce demand for our technology and harm our business. For example, the IRS issued Notice 2023-38 in May 2023 setting forth guidance on the domestic content bonus tax credits under the IRA, which introduced uncertainties that have yet to be fully resolved. In May 2024, the IRS issued Notice 2024-41 setting forth further guidance on the domestic content bonus tax credits, including a safe harbor method for calculating domestic content percentages. And in January 2025, the IRS issued Notice 2025-08, which provided an updated safe harbor method for calculating domestic content percentages. Notice 2024-41, Notice 2025-08 and the elective safe harbor described therein clarified some pre-existing uncertainty in the industry from Notice 2023-38, but they also introduced further uncertainties on some issues. These uncertainties have and could continue to cause our customers to delay projects as they navigate the existing guidance in qualifying for tax credits and possibly wait for further clarity. If we are unable to provide battery storage products that meet the domestic content requirements while our competitors are able to do so, we might experience a decline in sales of our products, which could adversely impact our results of operations and harm our business. Further, although these provisions generally subsidize battery storage both in front of and behind the meter, they may benefit other companies in unexpected ways and thus weaken our competitive position. For example, the IRA may enable companies producing shorter duration lithium-ion batteries to compete with us through added volume of cells at lower cost.

In addition to the foregoing, on July 4, 2025, the One Big Beautiful Bill Act (H.R. 1) (the “OBBB”) was signed into law by the President of the United States. The OBBB contains a number of changes to the IRA that significantly impact the

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availability of the ITCs under Sections 48(a) and 48E of the Code, including the accelerated sunsetting of certain investment tax credits (including for solar projects), and certain limited restrictions on their transferability to third-parties for sale. In particular, ITCs for solar projects under Section 48E are terminated if they do not begin construction by July 4, 2026 unless such projects are placed in service by December 31, 2027, and the ITC under Section 48(a) has fully terminated for solar projects that did not begin construction by December 21, 2024. However, the sunset dates for ITCs for energy storage projects remain largely unchanged from the IRA. The OBBB also introduces significant restrictions beginning in 2026 around certain foreign entities, which will not only impact who can invest in renewable energy projects, but also who can supply components and know-how to develop them. Such foreign entity restrictions will apply not only to our customers but also to our energy storage technology manufacturing business for purposes of qualifying for the ITCs, PTCs, and Section 45X PTCS, but our domestic manufacturing and supply chain structure generally should benefit from the addition of these FEOC limitations, subject to our review of recently issued and future FEOC guidance. In addition to the foregoing legislative changes, on July 7, 2025, the President of the United States issued an Executive Order which directed the Secretary of the Treasury, within 45 days of the enactment of the OBBB, to enforce termination of the ITC for solar by issuing new and/or revised guidance related to established beginning of construction rules. In response to such Executive Order, the IRS issued Notice 2025-42 on August 15, 2025 that limits the methods that developers can use to determine whether they have begun construction for solar projects, in particular, removing a prior 5% safe harbor for beginning of construction (except for low-output solar facilities), Although Notice 2025-42 by its terms does not address energy storage technology and thus would not exclude it from such limitations, we cannot predict with certainty how it will impact our customers or our business going forward.

Furthermore, the OBBB imposed new eligibility qualifications for purposes of the Section 45X PTC for integrated components sold after December 31, 2026 to the effect that any primary component integrated into a secondary component must be produced within the same manufacturing facility, at least 65 percent of the total direct material costs of the secondary component must be attributable to primary components which are domestically mined, produced or manufactured, and the secondary component must be sold to a third party. The OBBB also modified the definition of a battery module to require that it include all essential functional equipment, such as current collector assemblies and voltage sense harnesses. The Company’s domestic manufacturing and supply chain structure generally should benefit from the foregoing revisions set forth in the OBBB, as enacted, subject to our review of recently issued and future FEOC guidance.

The full impact of the IRA and the OBBB, their accompanying guidance and any future legislation on our operations cannot be known with certainty. We are continuing to evaluate the potential overall impact and applicability of the IRA and OBBB and any further legislation, guidance or executive orders on our business and operations. To the extent that any impacts from the IRA or OBBB are less beneficial than anticipated or have a negative impact on us or our business or on our customers’ businesses, these changes may materially and adversely impact our business, financial condition, and results of operations. There is additional uncertainty on the future of certain of these incentives under the current U.S. presidential administration and Congress. Such uncertainty could in itself adversely impact customer demand and our business and future results of operations.

Changes in tax laws or in their implementation or interpretation may adversely affect our business and financial condition.

We are or may become subject to income- and non-income-based taxes in the United States under federal, state and local jurisdictions and in certain foreign jurisdictions in which we operate. Tax laws, regulations and administrative practices in these jurisdictions may be subject to significant change, with or without advance notice. For example, beginning in January 2022, the Tax Cuts and Jobs Act of 2017 (the “TCJA”) eliminated the right to deduct research and development expenditures for tax purposes in the period such expenses were incurred and instead requires all U.S. and foreign research and development expenditures to be amortized over five and fifteen tax years, respectively, and as a result, we have recognized a deferred tax asset for the future tax benefit of the amortization deductions of these capitalized research and development expenditures. The recently enacted OBBB eliminates the TCJA capitalization of domestic research and experimental expenditures for taxable years beginning on January 1, 2025, but retains the requirement to amortize foreign research and experimental expenditure over fifteen tax years.

Also, the IRA introduced a new non-deductible excise tax of 1% on certain net share repurchases by corporations. This 1% excise tax will generally apply to any repurchase of stock we undertake, net of shares issued by us in the same taxable year, which may increase the costs to us of any share repurchases.

Changes in tax laws, as well as other factors, could cause us to experience fluctuations in our tax obligations and effective tax rates and otherwise adversely affect our tax positions and/or our tax liabilities. Such changes may adversely affect our effective tax rates, cash flows and general business condition.

Our ability to utilize our net operating loss carryforwards and certain other tax attributes may be limited.

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As of December 31, 2025, we had U.S. federal and state net operating loss carryforwards of $334.7 million and $341.9 million, respectively. U.S. federal net operating loss carryforwards (“NOLs”) generated in taxable years beginning after December 31, 2017 do not expire, but for taxable years beginning after December 31, 2020, the deductibility of such U.S. federal NOLs is limited to 80% of our current year taxable income. Our remaining U.S. federal NOLs will expire beginning in 2032. Our state NOLs may also be subject to certain limitations. It is possible that we will not generate taxable income in time to use our NOLs before their expiration (if applicable) or at all.

Under Sections 382 and 383 of the Internal Revenue Code (the “Code”), if a corporation undergoes an “ownership change” (generally defined as a greater than 50 percentage points change (by value) in the ownership of its equity by certain stockholders over a rolling three-year period), the corporation’s ability to use its pre-change NOLs and certain other pre-change tax attributes to offset its post-change income and taxes may be limited. Similar provisions of state tax law may also apply to limit our use of accumulated state tax attributes. We may have experienced such ownership changes in the past, and we may experience ownership changes in the future as a result of shifts in our stock ownership, some of which are outside our control. Accordingly, our ability to utilize our NOLs and certain other tax attributes could be limited by an “ownership change” as described above, which could result in increased tax liability to the Company.

We are a smaller reporting company within the meaning of the Securities Act, and if we take advantage of certain exemptions from disclosure requirements available to “smaller reporting companies,” this could make our securities less attractive to investors and may make it more difficult to compare our performance with other public companies.

We are currently a “smaller reporting company” as defined in Regulation S-K of the Securities Act, which allows us to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not smaller reporting companies, including reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements. We will remain a smaller reporting company only until the last day of the fiscal year in which (i) the market value of the common stock held by non-affiliates exceeds $250,000,000 as of the prior June 30, or (ii) our annual revenues exceeded $100,000,000 during such completed fiscal year and the market value of the common stock held by non-affiliates exceeds $700,000,000 as of the prior June 30. To the extent we take advantage of such reduced disclosure obligations, it may also make comparison of our financial statements with other public companies difficult or impossible.

We cannot predict whether investors will find our securities less attractive because we expect to rely on these exemptions. If some investors find our common stock less attractive as a result of our reliance on these exemptions, the trading price of our common stock may be lower than it otherwise would be, there may be a less active trading market for our common stock and the trading price of our common stock may be more volatile.

Risks Related to Our Intellectual Property

If we fail to protect, or incur significant costs in defending, our intellectual property and other proprietary rights, then our business and results of operations could be materially harmed.

Our success depends to a significant degree on our ability to protect our intellectual property and other proprietary rights. We rely on a combination of patent, trademark, copyright, trade secret, and unfair competition laws, as well as confidentiality and other contractual provisions with our customers, suppliers, employees, and others, to establish and protect our intellectual property and other proprietary rights. Our ability to enforce these rights is subject to general litigation risks, as well as uncertainty as to the enforceability of our intellectual property rights in various countries. When we seek to enforce our rights, we may be subject to claims that our intellectual property rights are invalid or not enforceable. Our assertion of intellectual property rights may result in another party seeking to assert claims against us, which could harm our business. Our inability to enforce intellectual property rights under any of these circumstances would likely harm our competitive position and business.

We have applied for patents in multiple jurisdictions, including the United States, Europe, Australia, Japan and China, and under the Patent Cooperation Treaty, some of which have been issued. We cannot guarantee that any of our pending applications will be approved or that our existing and future intellectual property rights will be maintained or sufficiently broad to protect our proprietary technology, and any failure to obtain such approvals or finding that our intellectual property rights are invalid or unenforceable, or if we decline to continue certain intellectual property rights, could force us to, among other things, rebrand or re-design our affected products. In countries where we have not applied for patent protection or where effective intellectual property protection is not available to the same extent as in the United States, we may be at greater risk that our proprietary rights will be misappropriated, infringed, or otherwise violated or may be unprotectable. Government actions may also undermine our intellectual property rights.

Our intellectual property may be stolen or infringed. In the event of such theft or infringement, we may be required to initiate lawsuits to protect our significant investment in our intellectual property. So far, we have been neither the subject of any lawsuits challenging the ownership or validity of our intellectual property, nor have we been required to initiate any

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lawsuits to protect our intellectual property. However, any such lawsuits may consume management and financial resources for long periods of time and may not result in outcomes that are favorable or readily enforceable, which may adversely affect our business, financial condition or results of operations.

Third parties may assert that we are infringing upon their intellectual property rights, which could divert management’s attention, cause us to incur significant costs, and prevent us from selling or using the technology to which such rights relate.

Our competitors and other third parties hold numerous patents related to technology used in our industry. From time to time, we may also be subject to claims of intellectual property right infringement and related litigation, and, if we gain greater recognition in the market, we will face a higher risk of being the subject of claims that we have violated others’ intellectual property rights. While we believe that our products and technology do not infringe in any material respect upon any valid intellectual property rights of third parties, we cannot be certain that we would be successful in defending against any such claims. If we do not successfully defend or settle an intellectual property claim, we could be liable for significant monetary damages and could be prohibited from continuing to use certain technology, business methods, content, or brands. To avoid a prohibition, we could seek a license from the applicable third party, which could require us to pay significant royalties, increasing our operating expenses. If a license is not available at all or not available on reasonable terms, then we may be required to develop or license a non-infringing alternative, either of which could require significant effort and expense. If we cannot license or develop a non-infringing alternative, we would be forced to revise, limit or stop sales of our offerings and may be unable to effectively compete and subject to termination and indemnification obligations under our contracts. Any of these results would adversely affect our business, financial condition and results of operations.

Our patent applications may not result in issued patents or our patent rights may be contested, circumvented, invalidated or limited in scope, any of which could have a material adverse effect on our ability to prevent others from interfering with the commercialization of our products.

Our patent applications may not result in issued patents, which may have a material adverse effect on our ability to prevent others from commercially exploiting products similar to ours. The status of patents involves complex legal and factual questions and the breadth of claims allowed is uncertain. As a result, we cannot be certain that the patent applications that we file will result in patents being issued, or that our patents and any patents that may be issued to us will afford protection against competitors with similar technology. Numerous patents and pending patent applications owned by others exist in the fields in which we have developed and are developing our technology. In addition, there are numerous academic papers and other publications in our field of technology. As a result, our existing or pending patents may be subject to challenge on the basis of prior art. Furthermore, patent applications filed in foreign countries are subject to laws, rules and procedures that differ from those of the United States, and thus we cannot be certain that foreign patent applications related to issued U.S. patents will be issued.

Even if our patent applications succeed and we are issued patents in accordance with them, we are still uncertain whether these patents will be contested, circumvented, invalidated or limited in scope in the future. The rights granted under any issued patents may not provide us with meaningful protection or competitive advantages, and some foreign countries provide significantly less effective patent enforcement than in the United States. In addition, the claims under any patents that issue from our patent applications may not be broad enough to prevent others from developing technologies that are similar or that achieve results similar to ours. The intellectual property rights of others could also bar us from licensing and exploiting any patents that issue from our pending applications. In addition, patents issued to us may be infringed or designed around by others and others may obtain patents that we need to license or design around, either of which would increase costs and may adversely affect our business, financial condition and results of operations.

Our products contain third-party open-source software components, and failure to comply with the terms of the underlying open source software licenses could restrict our ability to sell our products or our use of those components give rise to disclosure obligations of proprietary software.

Our products contain components that are licensed under so-called “open source,” “free” or other similar licenses. Open source software is made available to the general public on an “as-is” basis under the terms of a non-negotiable license. Certain open source licenses may give rise to obligations to disclose or license our source code or other intellectual property rights if such open source software is integrated with our proprietary software or used or distributed in certain ways. We currently combine and use our proprietary software with open source software, but not in a manner that we believe requires the release of the source code of our proprietary software to the public. If we combine, use or distribute our proprietary software with open source software in a certain manner in the future, we could be required to release the source code to our proprietary software as open source software, or could be required to cease using the relevant open source software which might be costly to replace. Open source licensors also generally do not provide warranties or other contractual protections regarding infringement claims or the quality of the code. In addition, if the license terms for the open source software that we use change, we may be forced to re-engineer our software, incur additional costs or

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discontinue the use of certain offerings if re-engineering could not be accomplished in a timely manner. Although we monitor our use of open source software to avoid subjecting our offerings to unintended conditions, there is a risk that these licenses could be construed in a way that could impose unanticipated conditions or restrictions on our ability to commercialize our offerings. We cannot guarantee that we have incorporated open source software in our software in a manner that will not subject us to liability or in a manner that is consistent with our current policies and procedures.

Risks Related to Raising Capital

As we endeavor to expand our business, we will incur significant costs and expenses, which could outpace our cash reserves. Unfavorable conditions or disruptions in the capital and credit markets may adversely impact business conditions and the availability of credit.

We expect to incur additional costs and expenses in the future related to the continued development and expansion of our business, including in connection with expanding our manufacturing capabilities to significantly increase production capacity, developing our products, maintaining and enhancing our research and development operations, expanding our sales, marketing, and business development activities in the United States and internationally, and growing our project management, field services and overall operational capabilities for delivering projects. We do not know whether our revenues will grow rapidly enough to absorb these costs or the extent of these expenses or their impact on our results of operations.

Disruptions in the global capital and credit markets as a result of an economic downturn, economic uncertainty, changing or increased regulation, or failures of significant financial institutions, as well as any negative perceptions about our long-term business prospects or the renewable energy sector as a whole, even if exaggerated or unfounded, could adversely affect our customers’ ability to access capital and could adversely affect our access to liquidity needed for business in the future. If we or our customers are unable to obtain additional capital as required, whether due to such disruptions or otherwise, we may be required to take further measures to conserve cash, including ongoing evaluation of workforce staffing requirements, further reduction of material purchases by continuing to minimize spending until firm orders are received, refining our focus on research and development and engineering project efforts towards highest priority, greatest return projects and additional reduction in outside vendor spending, until alternative credit arrangements or other funding for our business needs can be arranged, which may adversely affect our business, financial condition and results of operations.

We will need to raise additional capital in the near future, and it may not be available on acceptable terms, if at all.

We have incurred operating losses and cash outflows from operations since inception and we anticipate that losses will continue in the near term. During the year ended December 31, 2025, we have incurred net losses of $63.4 million and used $50.3 million of cash in operating activities. As of December 31, 2025, we had unrestricted cash and cash equivalents of $14.5 million and short-term investments of 7.5 million, or total liquid assets of $22.0 million.

As discussed in “Part II—Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources”, we will need additional debt or equity financing, strategic partnerships or other arrangements in order to meet our near-term operating cash flow requirements, and management continues to explore various alternatives for raising capital to facilitate our growth and execute our business strategy. However, these sources of capital may not be available on acceptable terms, or at all. Our ability to obtain additional financing will be subject to a number of factors, including market conditions, our operating performance, the price of our common stock, investor sentiment generally or about the renewable energy sector specifically and our ability to incur additional debt in compliance with agreements governing our then-outstanding debt. These factors may make the timing, amount, terms or conditions of additional financings unattractive to us.

We may issue additional shares of our common stock or other equity securities in the future including pursuant to an ATM offering and in connection with, among other things, future acquisitions or grants under the ESS Tech, Inc. 2021 Equity Incentive Plan (the “2021 Plan”) and the Employee Stock Purchase Plan (the “ESPP”) without stockholder approval in a number of circumstances. Sales of our common stock in an ATM offering will also depend upon market conditions and other factors, including our liquidity needs, our trading volume and the share price of our common stock during the applicable pricing period for each sale.

The issuance of additional shares of common stock or other equity securities could have, among other things, one or more of the following effects: our existing stockholders’ proportionate ownership interest will decrease; the amount of cash available per share, including for payment of dividends in the future, may decrease; the relative voting strength of each previously outstanding share of our common stock may be diminished; and the market price of our common stock and/or warrants may decline.

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If we raise additional funds by issuing debt securities, those securities may have rights, preferences or privileges senior to the rights of our currently issued and outstanding equity or debt. In addition, issued debt securities may contain covenants and limit our ability to pay dividends or make other distributions to stockholders. If we are unable to generate sufficient funds from operations or raise additional capital, our future operations and growth could be impeded or discontinued. These uncertainties cause substantial doubt to exist as to our ability to continue as a going concern for 12 months from the issuance of the financial statements included in this Annual Report on Form 10-K. If we become unable to continue as a going concern, we could have to liquidate our assets, and potentially realize significantly less than the values at which they are carried on our financial statements, and stockholders could lose all or part of their investment in our common stock.

In response to the delay in obtaining funding commitments and negative macroeconomic trends, we have expanded certain cost reduction and cash conservation measures, including ongoing evaluation of workforce staffing requirements and essential business functions, and the implementation of a furlough for a substantial number of our employees as of May 30, 2025 to better align organizational costs with business continuity, further reduction of material purchases by continuing to minimize spending until firm orders are received, refining our focus on research and development and engineering project efforts towards highest priority, greatest return projects and additional reduction in outside vendor spending, and we may implement further measures. Such cash conservation activities may yield unintended consequences, such as attrition beyond any planned reduction in workforce or near-term delays in our ability to deliver products to our customers.

Our debt service obligations may adversely affect our financial condition and cash flows from operations.

On November 1, 2024, we entered into a Credit Agreement by and between the Company, as borrower, and Export-Import Bank of the United States, as lender, and related agreements related to the financing of two production lines. As of December 31, 2025, we had no outstanding borrowings under the Credit Agreement. The Credit Agreement provides for a secured loan facility in an aggregate principal amount of up to $22.7 million, of which $20 million is available to be borrowed for equipment financing and the balance will be used to finance an exposure fee and transaction expenses. The loan facility has a maturity date of June 30, 2031. Half of the proceeds of the loan facility may be used on a retroactive basis for the financing of our existing automated battery assembly line and the remainder may be used for the financing or refinancing of an additional line upon the closing of an equity raise milestone.

The Credit Agreement contains customary affirmative and negative covenants, including covenants limiting our ability to, among other things, grant liens, undergo certain fundamental changes, use financed goods for an unapproved purpose, make certain restricted payments, dispose of assets, and modify the project site lease, in each case, subject to limitations and exceptions set forth in the Credit Agreement. We are also required to meet or exceed specified trailing four quarter revenue targets, which financial covenant is tested quarterly.

Our obligations under the Credit Agreement are secured pursuant to a security agreement granting EXIM a first priority security interest in the financed equipment and a securities account containing collateral consisting of cash and cash equivalents in an amount equal to a substantial portion of the disbursements under the Credit Agreement that decreases upon the equity raise milestone and will be reported as restricted cash.

The Credit Agreement contains customary events of default including, among others, certain payment defaults, indebtedness cross defaults, covenant defaults, a change of control default, a material adverse change default, bankruptcy and insolvency defaults and judgment defaults. If an event of default exists, EXIM may require immediate payment of all obligations under the Credit Agreement and may exercise certain other rights and remedies provided for under the Credit Agreement, the other credit documents and applicable law. In the event of a payment default, a default interest rate will apply.

Additionally, on October 14, 2025, we issued a Promissory Note to YA II PN, LTD (the “Investor”, “Yorkville”), in the aggregate principal amount of up to $40 million (the “Promissory Note”), in two tranches consisting of a first tranche of $30 million and a second tranche of $10 million, in each case less an original issue discount of 8% and certain fees and expenses. The Promissory Note contains customary events of default.

Maintenance of our existing and any future indebtedness could also:

•cause us to dedicate a substantial portion of our cash flows from operations towards debt service obligations and principal repayments;

•increase our vulnerability to adverse changes in general economic, industry, and competitive conditions;

•limit our flexibility in planning for, or reacting to, changes in our business and our industry;

•impair our ability to obtain future financing for working capital, capital expenditures, acquisitions, general corporate, or other purposes; and

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•due to limitations within the debt instruments, restrict our ability to grant liens on property, enter into certain mergers, dispose of all or substantially all of our assets, or materially change our business, subject to customary exceptions.

Risks Related to Our Common Stock and Warrants

The price of our common stock may be volatile.

The price of our common stock may fluctuate due to a variety of factors, including:

•changes in the industries in which we and our customers operate;

•variations in our operating performance and the performance of our competitors in general;

•actual or anticipated fluctuations in our quarterly or annual operating results;

•the public’s reaction to our press releases, our other public announcements and our filings with the SEC;

•our failure or the failure of our competitors to meet analysts’ projections or guidance that we or our competitors may give to the market;

•additions and departures of key personnel;

•changes in laws and regulations affecting our business;

•commencement of, or involvement in, litigation involving us;

•changes in our capital structure, such as future issuances of securities or the incurrence of additional debt;

•publication of research reports by securities analysts about us or our competitors or our industry;

•sales of shares of our common stock by our existing stockholders;

•short selling activities;

•the trading volume of our shares and the volume of shares of our common stock available for public sale; and

•general economic and political conditions such as recessions, interest rates, fuel prices, inflation, instability in the banking sector and financial markets, foreign currency fluctuations, changing international trade policies, social, political and economic risks, hostilities or the perception that hostilities may be imminent, terrorism, military conflict and acts of war, including the escalation of the Russia-Ukraine conflict, geopolitical tensions involving China, the conflict between the U.S., Israel and Iran, tensions in the Middle East, and U.S. interventions in Venezuela and the related responses, including sanctions or other restrictive actions, by the United States and/or other countries.

These market and industry factors may materially reduce the market price of our common stock regardless of our operating performance and such impact may be exacerbated during periods of greater economic and market volatility.

In addition, we have been and in the future may again be the subject of a report issued by activist short sellers. Any such report, even if it contains false and misleading statements about the Company, may cause our stock price to experience volatility.

A sale of a significant portion of our total outstanding shares into the market may cause the market price of our common stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market could occur at any time, including pursuant to an ATM offering. These sales, or the perception in the market that the holders of a large number of shares intend to sell shares, could reduce the market price of our common stock. In particular, because the purchase price per share to be paid by the investors for shares of common stock that we may elect to sell in an ATM offering would fluctuate based on the market prices of our common stock during the applicable pricing period for each of those sales, it is not possible for us to predict, the number of shares of common stock that we would sell in such an offering, the purchase price per share or the net proceeds that we would receive from those purchases in such an offering. At a lower purchase price per share or if our need for additional liquidity is greater or occurs sooner than expected, we may also sell a correspondingly larger number of shares in an ATM offering. Further, the resale by the Investor of a significant amount of shares at any given time, or the perception that these sales may occur, could cause the market price of our common stock to decline and to be highly volatile.

We maintain a shelf registration statement on Form S-3 pursuant to which we may, from time to time, sell up to an aggregate of $300 million of our common stock, preferred stock, debt securities, depositary shares, warrants, subscription

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rights, purchase contracts, or units. We have also filed, or may be required to file, registration statements with the SEC to register shares of our common stock for certain stockholders who have rights, subject to certain conditions, to require us to file registration statements covering their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. We have also filed registration statements with the SEC to register shares reserved for future issuance under our equity compensation plans. Registration of these shares under the Securities Act results in the shares becoming freely tradable in the public market, subject to the restrictions of Rule 144 in the case of our affiliates.

Any issuance of securities under the shelf registration statement may cause stockholders to experience significant dilution of their ownership interests and any sales of securities by us or our stockholders under the registration statements could have a material adverse effect on the market price for our common stock. For example, we sold an aggregate of 6,458,634 shares of common stock at a weighted average sales price of $3.87 per share under the July Standby Equity Purchase Agreement (“SEPA”) and issued an additional 157,768 shares of common stock as a commitment fee, each of which were dilutive to our shareholders. Sales of our common stock pursuant to the exercise of registration rights may make it more difficult for us to sell equity securities in the future at a time and at a price that we deem appropriate. These sales also could cause the trading price of our common stock to fall and make it more difficult for you to sell shares of our common stock at a time and price that you deem appropriate.

We have warrants outstanding that are exercisable for our common stock, which, if exercised, would increase the number of shares eligible for future resale in the public market and result in dilution to our stockholders.

As of December 31, 2025, we had outstanding 11,461,227 Public Warrants to purchase an aggregate of 764,081 shares of our common stock. Each fifteen Public Warrants are exercisable for one share of common stock at an exercise price of $172.50 per share. We also had outstanding a warrant issued to SMUD exercisable for up to 33,333 shares of our common stock, with the vesting of the shares underlying the warrant being subject to the achievement of certain commercial milestones through December 31, 2030 pursuant to a related commercial agreement; the Investment Warrant held by Honeywell Ventures exercisable for up to 708,775 shares of common stock; the IP Warrant held by Honeywell Ventures exercisable for up to 417,997 shares of common stock; and the initial Performance Warrant held by UOP exercisable for up to 51,717 shares of common stock. The warrant issued to SMUD has an exercise price of $64.44 per share, the Investment Warrant has an exercise price of $28.35 per share, the IP Warrant has an exercise price of $43.50 per share and the initial Performance Warrant has an exercise price of $21.75 per share. We may issue additional Performance Warrants to UOP (not to exceed an aggregate value of $15 million based on target purchase amounts of up to $300 million by 2030) on an annual basis for the five-year period beginning in 2026, based on UOP’s purchase of additional equipment pursuant to the Supply Agreement. The additional Performance Warrants will have an exercise price equal to the volume-weighted average price of our common stock for the last fifteen (15) trading days of the relevant calendar year for which such additional Performance Warrant is being issued. On July 10, 2025, we also issued warrants exercisable for an aggregate number of up to 129,312 shares of common stock at an exercise price of $3.48 per share (the “Bridge Financing Warrants”) and on October 14, 2025, we issued to the Investor the Promissory Note Warrant exercisable for an aggregate number of up to 1,052,104 shares of common stock at an exercise price of $9.98 per share.

To the extent such warrants are exercised, additional shares of our common stock will be issued, which will result in dilution to the holders of our common stock and increase the number of shares eligible for resale in the public market. Sales of substantial numbers of such shares in the public market or the fact that such warrants may be exercised could adversely affect the prevailing market prices of our common stock. For further information, see Note 13, Common Stock Warrants, to our consolidated financial statements in this Annual Report on Form 10-K.

The terms of our warrants may be amended from time to time.

Our Public Warrants were issued in registered form under a warrant agreement with Continental Stock Transfer & Trust Company, as warrant agent. The warrant agreement provides that the terms of the Public Warrants may be amended without the consent of any holder to cure any ambiguity or correct any defective provision or correct any mistake, but requires the approval by the holders of 65% of the then-outstanding Public Warrants to make any change that adversely affects the interests of the registered holders of Public Warrants. Accordingly, we may amend the terms of the Public Warrants in a manner adverse to a holder if holders of 65% of the then-outstanding Public Warrants approve of such amendment. Although our ability to amend the terms of the Public Warrants with the consent of 65% of the then-outstanding Public Warrants is unlimited, examples of such amendments could be amendments to, among other things, increase the exercise price of the warrants, convert the warrants into cash, shorten the exercise period or decrease the number of shares of our common stock purchasable upon exercise of a warrant. We may also lower the exercise price for our Public Warrants in our sole discretion at any time prior to the expiration date, subject to compliance with certain notice and timing requirements. The warrant issued to SMUD, the Investment Warrant, the IP Warrant and the initial Performance Warrant may all be amended with the consent of the respective holders thereof. The Bridge Financing Warrants may be amended with the consent of the holders of 50% of the aggregate amount outstanding of such warrants.

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We may redeem your unexpired warrants prior to their exercise at a time that is disadvantageous to you, thereby making your warrants worthless.

We have the ability to redeem the outstanding Public Warrants at any time after they become exercisable and prior to their expiration, at a price of $0.01 per warrant, provided that the closing price of our common stock equals or exceeds $270.00 per share (as adjusted for share subdivisions, share dividends, rights issuances, subdivisions, reorganizations, recapitalizations and the like) for any 20 trading days within a 30 trading-day period ending on the third trading day prior to proper notice of such redemption and provided that certain other conditions are met. If and when the warrants become redeemable by us, we may exercise our redemption right even if we are unable to register or qualify the underlying securities for sale under all applicable state securities laws. As a result, we may redeem the warrants as set forth above even if the holders are otherwise unable to exercise the warrants. Redemption of the outstanding warrants could force you to (i) exercise your warrants and pay the exercise price therefor at a time when it may be disadvantageous for you to do so, (ii) sell your warrants at the then-current market price when you might otherwise wish to hold your warrants or (iii) accept the nominal redemption price which, at the time the outstanding warrants are called for redemption, we expect would be substantially less than the market value of your warrants.

In addition, we have the ability to redeem the outstanding Public Warrants at any time after they become exercisable and prior to their expiration, at a price of $0.10 per warrant upon a minimum of 30 days’ prior written notice of redemption provided that the closing price of our common stock equals or exceeds $150.00 per share (as adjusted for adjustments to the number of shares issuable upon exercise or the exercise price of a warrant) for any 20 trading days within a 30 trading-day period ending on the third trading day prior to proper notice of such redemption and provided that certain other conditions are met, including that holders will be able to exercise their warrants prior to redemption for a number of shares of common stock determined based on the redemption date and the fair market value of our common stock. The value received upon exercise of the warrants (1) may be less than the value the holders would have received if they had exercised their warrants at a later time where the underlying share price is higher and (2) may not compensate the holders for the value of the warrants, including because the number of ordinary shares received is capped at 0.02407 shares of common stock per warrant (subject to adjustment) irrespective of the remaining life of the warrants.

We do not expect to declare any dividends in the foreseeable future.

We do not anticipate declaring any cash dividends to holders of our common stock in the foreseeable future. Consequently, investors may need to rely on sales of their shares after price appreciation, which may not occur for some time or not at all, as the only way to realize any future gains on their investment.

There can be no assurance that we will be able to continue to satisfy the continued listing standards of the NYSE.

On March 24, 2025, we received a written notice from the NYSE (the “Notice”) indicating that we did not satisfy the continued listing standard set forth in Section 802.01B of the NYSE’s Listed Company Manual, as our average global market capitalization over a consecutive 30 trading-day period was less than $50 million (the “Minimum Market Capitalization Standard”) and, at the same time, our stockholders’ equity was less than $50 million. As described in the Notice, as of March 21, 2025, our 30 trading-day average global market capitalization was approximately $47.8 million and our last reported stockholders’ equity as of September 30, 2024, was approximately $49.2 million.

In accordance with applicable NYSE procedures, we timely submitted a plan to the NYSE on May 7, 2025 advising it of the definitive actions we have taken, are taking, or plan to take that we anticipate will bring us into conformity with the NYSE’s Minimum Market Capitalization Standard within 18 months of receipt of the Notice (the “Cure Period”). On June 17, 2025, the NYSE observed and notified us that our then current global market capitalization was less than $15 million. Section 802.01B of the NYSE’s Listed Company Manual provides that the NYSE will promptly initiate suspension and delisting procedures if a company is determined to have an average global market capitalization over a consecutive 30 trading-day period of less than $15 million regardless of the original standard under which it listed.

On August 19, 2025, we received written notice that the NYSE’s Listings Operations Committee accepted our submission, and NYSE Regulation senior management acknowledged the acceptance. The NYSE will conduct quarterly reviews during the 18 months from our receipt of the Notice for compliance with the goals and initiatives outlined in our plan (the “Plan Period”). In addition, at the beginning of each fiscal quarter during the Plan Period, the NYSE will disclose to us any unpaid listing and annual fees owed by us to the NYSE exchange as of the end of the most recently completed calendar quarter. During our Plan Period, we will not be considered to be in compliance with our plan unless we have paid in full all of the aforementioned outstanding fees.

If either (1) we fail to comply with our plan or do not meet the NYSE’s Minimum Market Capitalization Standard at the end of the Cure Period, (2) we are determined to have an average global market capitalization over a consecutive 30 trading-day period of less than $15 million, or (3) do not pay all outstanding fees within 45 days of the quarterly disclosure

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of any such fees and prior to the completion of our Plan Period, we will be subject to NYSE’s prompt initiation of suspension and delisting procedures.

If the NYSE delists our securities from trading on its exchange and we are not able to list such securities on another national securities exchange, we expect such securities could be quoted on an over-the-counter market. If this were to occur, we and our stockholders could face significant material adverse consequences including:

•a limited availability of market quotations for our securities;

•reduced liquidity for our securities;

•a determination that our common stock is a “penny stock” which would require brokers trading in the common stock to adhere to more stringent rules, possibly resulting in a reduced level of trading activity in the secondary trading market for our shares of common stock;

•a limited amount of news and analyst coverage;

•a decreased ability or even an inability to issue additional securities or obtain additional financing in the future, including pursuant to an ATM offering; and

•an impairment of our ability to provide equity incentives to our employees.

In the event of a delisting, we can provide no assurance that any action taken by us to restore or otherwise meet compliance with listing requirements would allow our securities to become listed again, stabilize the market price or improve the liquidity of our securities, or prevent future non-compliance with the NYSE’s or another exchange’s listing requirements.

Reports published by analysts, including projections in those reports that differ from our actual results, could adversely affect the price and trading volume of our common stock.

Securities research analysts may establish and publish their own periodic projections for us. These projections may vary widely and may not accurately predict the results we actually achieve. Our share price may decline if our actual results do not match the projections of these securities research analysts. Similarly, if one or more of the analysts who write reports on us downgrades our stock or publishes inaccurate or unfavorable research about our business, our share price could decline. If one or more of these analysts ceases coverage of us or fails to publish reports on us regularly, our share price or trading volume could decline.

We may be subject to short selling strategies that may drive down the market price of our common stock.

Short selling occurs when an investor borrows a security and sells it on the open market, with the intention of buying identical securities at a later date to return to the lender. A short seller hopes to profit from a decline in the value of the securities between the sale of the borrowed securities and the purchase of the replacement shares. Because it is in the short seller’s best interests for the price of the stock to decline, some short sellers publish, or arrange for the publication of, opinions or characterizations regarding the relevant issuer, its business prospects, and similar matters calculated to or which may create negative market momentum. Short sellers can publicly attack a company’s reputation and business on a broader scale via online postings. In the past, the publication of such commentary about us by a self-described short seller has precipitated a decline in the market price of our common stock, and future similar efforts by other short sellers may have similar effects. Companies that are subject to unfavorable allegations promoted by short sellers, even if untrue, may have to expend a significant amount of resources to investigate such allegations and defend themselves.

Provisions in our amended and restated certificate of incorporation, as amended, and amended and restated bylaws and Delaware law might discourage, delay or prevent a change in control of the Company or changes in management and, therefore, depress the market price of our common stock.

Our certificate of incorporation (as amended, the “Charter”) and amended and restated bylaws contain provisions that could delay or prevent a change of control of the Company or changes in our board of directors that our stockholders might consider favorable. These provisions, among other things:

•establish a classified board of directors so that not all members of our board are elected at one time;

•permit only our board of directors to establish the number of directors and fill vacancies on the board;

•provide that directors may only be removed “for cause” and only with the approval of a majority of the voting power of the issued and outstanding capital stock of the Company entitled to vote in the election of directors;

•authorize the issuance of “blank check” preferred stock that our board could use to implement a stockholder rights plan (also known as a “poison pill”);

•eliminate the ability of our stockholders to call special meetings of stockholders;

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•prohibit stockholder action by written consent, which requires all stockholder actions to be taken at a meeting of our stockholders;

•prohibit cumulative voting by stockholders at any election of directors;

•authorize our board of directors to amend the bylaws;

•establish advance notice requirements for nominations for election to our board or for proposing matters that can be acted upon by stockholders at annual stockholder meetings; and

•require a super-majority vote of stockholders to amend some of the provisions described above.

In addition, Section 203 of the Delaware General Corporation Law (the “DGCL”), prohibits a publicly held Delaware corporation from engaging in a business combination with an interested stockholder, generally a person which together with its affiliates owns, or within the last three years has owned, 15% of our voting stock, for a period of three years after the date of the transaction in which the person became an interested stockholder, unless the business combination is approved in a prescribed manner.

Any provision of our Charter, amended and restated bylaws or Delaware law that has the effect of delaying or preventing a change in control could limit the opportunity for our stockholders to receive a premium for their shares of our capital stock and could also affect the price that some investors are willing to pay for our common stock.

Our amended and restated bylaws provide that the Court of Chancery of the State of Delaware and the federal district courts of the United States of America will be the exclusive forums for certain stockholder litigation matters, which could limit our stockholders’ ability to obtain a favorable judicial forum for disputes with us or our directors, officers or employees.

Our amended and restated bylaws provide that the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, another State court in Delaware or the federal district court for the District of Delaware) is the exclusive forum for the following (except for any claim as to which such court determines that there is an indispensable party not subject to the jurisdiction of such court (and the indispensable party does not consent to the personal jurisdiction of such court within 10 days following such determination), which is vested in the exclusive jurisdiction of a court or forum other than such court or for which such court does not have subject matter jurisdiction):

•any derivative action or proceeding brought on our behalf;

•any action asserting a claim of breach of fiduciary duty owed by any director, stockholder, officer or other employee of the Company to the Company or to the Company’s stockholders;

•any action arising pursuant to any provision of the DGCL, our Charter or our amended and restated bylaws; and

•any action asserting a claim against us that is governed by the internal affairs doctrine.

This provision would not apply to suits brought to enforce a duty or liability created by the Securities Act, the Exchange Act or any other claim for which the U.S. federal courts have exclusive jurisdiction.

Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all such Securities Act actions. Accordingly, both state and federal courts have jurisdiction to entertain such claims. To prevent having to litigate claims in multiple jurisdictions and the threat of inconsistent or contrary rulings by different courts, among other considerations, our amended and restated bylaws further provide that, unless the Company consents in writing to the selection of an alternative forum, the federal district courts of the United States of America will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act against any person in connection with any offering of the Company’s securities, including any auditor, underwriter, expert, control person, or other defendant. We note that investors cannot waive compliance with the federal securities laws and the rules and regulations thereunder.

These exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers or other employees, which may discourage lawsuits against us and our directors, officers and other employees. Any person or entity purchasing, holding or otherwise acquiring any interest in any of our securities shall be deemed to have notice of and consented to these provisions. There is uncertainty as to whether a court would enforce such provisions, and the enforceability of similar choice of forum provisions in other companies’ charter documents has been challenged in legal proceedings. While the Delaware courts have determined that such choice of forum provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a venue other than those designated in the exclusive forum provisions, and there can be no assurance that such provisions will be enforced by a court in those other jurisdictions. If a court were to find these types of provisions to be inapplicable or unenforceable, and if a court were to find the exclusive forum provision in our amended and restated bylaws to be inapplicable or unenforceable

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in an action, we may incur additional costs associated with resolving the dispute in other jurisdictions, which could materially adversely affect our business.

Claims for indemnification by our directors and officers may reduce our available funds to satisfy successful third-party claims against us and may reduce the amount of money available to us.

Our Charter and amended and restated bylaws provide that we will indemnify our directors and officers, in each case to the fullest extent permitted by Delaware law.

In addition, as permitted by Section 145 of the DGCL, our amended and restated bylaws and our indemnification agreements that we have entered into with our directors and officers provide that:

•we indemnify our directors and officers for serving us in those capacities or for serving other business enterprises at our request, to the fullest extent permitted by Delaware law. Delaware law provides that a corporation may indemnify such person if such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the registrant and, with respect to any criminal proceeding, had no reasonable cause to believe such person’s conduct was unlawful;

•we may, in our discretion, indemnify employees and agents in those circumstances where indemnification is permitted by applicable law;

•we are required to advance expenses, as incurred, to our directors and officers in connection with defending a proceeding, except that such directors or officers shall undertake to repay such advances if it is ultimately determined that such person is not entitled to indemnification;

•we are not obligated, pursuant to our amended and restated bylaws, to indemnify a person with respect to proceedings initiated by that person against us or our other indemnitees, except with respect to proceedings authorized by our board of directors or brought to enforce a right to indemnification;

•the rights conferred in our amended and restated bylaws are not exclusive, and we are authorized to enter into indemnification agreements with our directors, officers, employees and agents and to obtain insurance to indemnify such persons; and

•we may not retroactively amend our amended and restated bylaw provisions to reduce our indemnification obligations to directors; officers, employees and agents.

While we maintain a directors’ and officers’ insurance policy to the fullest extent permitted by the DGCL, such insurance may not be adequate to cover all liabilities that we may incur, which may reduce our available funds to satisfy third-party claims and may materially adversely affect our cash position.

ITEM 1B. UNRESOLVED STAFF COMMENTS

None.

ITEM 1C. CYBERSECURITY

Risk Management and Strategy

We have established policies and processes for assessing, identifying, and managing risk from cybersecurity threats, and have integrated these processes into our overall risk management systems and processes. We measure our cybersecurity infrastructure against the NIST 800-171 framework and routinely assess risks from cybersecurity threats, including any potential unauthorized occurrence on or conducted through our information systems that may result in adverse effects on the confidentiality, integrity, or availability of our information systems or any information residing therein.

We conduct regular technical risk assessments to identify cybersecurity threats, as well as assessments in the event of a material change in our business practices that may affect information systems that are vulnerable to such cybersecurity threats. We also conduct periodic programmatic risk assessments including identification of reasonably foreseeable internal and external risks, the likelihood and potential damage that could result from such risks, and the sufficiency of existing policies, procedures, systems, and safeguards in place to manage such risks.

Following these risk assessments, we evaluate whether and how to re-design, implement, and maintain reasonable safeguards to minimize identified risks; evaluate how to reasonably address any identified gaps in existing safeguards; and regularly monitor the effectiveness of our safeguards. We devote significant resources and designate high-level personnel, including our interim Chief Operating Officer, whose oversight includes information technology and cybersecurity and who reports to our Chief Executive Officer, to manage the risk assessment and mitigation process.

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As part of our overall risk management system, we monitor and test our safeguards and train our employees on these safeguards, in collaboration with human resources, IT, and management. Personnel at all levels and departments are made aware of our cybersecurity policies through trainings and annual policy acknowledgments.

We engage external cyber vendor consultants, auditors, and other third parties in connection with our risk assessment processes. These service providers assist us to assess, design and implement our cybersecurity policies and procedures, as well as to monitor and test our safeguards.

We review the ability of third-party service providers to implement and maintain appropriate security measures, consistent with all applicable laws, to implement and maintain reasonable security measures in connection with their work with us, and to promptly report any suspected breach of its security measures that may affect our Company.

For additional information regarding whether any risks from cybersecurity threats, including as a result of any previous cybersecurity incidents, have materially affected or are reasonably likely to materially affect our Company, including our business strategy, results of operations, or financial condition, please refer to Item 1A, “Risk Factors,” in this Annual Report on Form 10-K, including the risk factors entitled “Third parties might attempt to gain unauthorized access to our network or seek to compromise our products and services.”

Governance

One of the key functions of our board of directors is informed oversight of our risk management process, including risks from cybersecurity threats. Our board of directors is responsible for monitoring and assessing strategic risk exposure, and our executive officers are responsible for the day-to-day management of the material risks we face. Our board of directors administers its cybersecurity risk function in coordination with the oversight and periodic review of the audit committee.

In accordance with our cybersecurity incident response plan (“IRP”), our interim Chief Operating Officer, members of our management team, including personnel representative of the following functions – legal, IT, finance, audit, operations, engineering, human resources, communications, and additional executives as applicable under the plan – and external cybersecurity support providers (collectively, “IRP stakeholders”), are primarily responsible to assess and manage risks from cybersecurity threats.

Our interim Chief Operating Officer and our IRP stakeholders oversee our cybersecurity policies and processes, including those described in “Risk Management and Strategy” above. Our interim Chief Operating Officer has an advanced degree in management information systems and has managed the Company’s IT processes and policies inclusive of cybersecurity matters throughout his tenure at the Company, in addition to many years of prior experience in various technology roles at a large U.S. public company. He is informed about and monitors the prevention, detection, mitigation, and remediation of cybersecurity incidents by working with the IT department and external vendors to implement our security risk management, including through the use of both automated and manual tools and reporting, in accordance with the Company’s incident response plan and Company cybersecurity policies.

Our interim Chief Operating Officer provides quarterly briefings to the audit committee and board of directors regarding our Company’s cybersecurity program, including risks and activities, reports of recent cybersecurity incidents and related responses (if any, and if not previously reported to the Board pursuant to the incident response plan), cybersecurity systems testing, the status of third party assessments, general updates in the cybersecurity space, relevant disclosures related to SEC reporting, and the like.

ITEM 2. PROPERTIES

Our corporate headquarters is located in Wilsonville, Oregon. The approximately 200,000 square foot facility contains both our corporate, engineering, and administrative functions as well as our automated and semi-automated battery manufacturing lines. During 2025, the facility had the capacity to manufacture approximately 560 MWh of batteries annually. We currently are in the process of commissioning a second automated battery manufacturing line and repurposing our original semi-automated line for research and development activities. This will result in a total battery manufacturing capacity of 1.05 GWh annually.

Over time, we plan to increase efficiency at the Wilsonville facility to scale manufacturing capacity up to 2.0 GWh through a combination of additional manufacturing lines as well as substantive improvements to the capacity of each battery produced. We also envision opening additional manufacturing facilities globally. This global expansion plan may include the following levers that are currently under consideration:

•Strategic investments in the supply chain to grow capacity;

•Production expansion to Europe and/or Australia; and

•Vertical integration of power module compartments.

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ITEM 3. LEGAL PROCEEDINGS

From time to time, we may become involved in legal proceedings arising in the ordinary course of our business. We are not currently a party to any material legal proceedings, nor, to our knowledge, is any material legal proceeding threatened against us. In the future, we may become involved in legal proceedings that arise in the ordinary course of business, the outcome of which, if determined adversely to us, could individually or in the aggregate have a material adverse effect on our business, financial condition and results of operations.

ITEM 4. MINE SAFETY DISCLOSURES

Not applicable.

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PART II

ITEM 5. MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASE OF EQUITY SECURITIES

Market Information and Holders

Our common stock is listed on the NYSE under the symbol “GWH” and our Public Warrants are listed on the NYSE under the symbol “GWH.W”. As of February 27, 2026, there were 16 holders of record of our common stock and 1 holder of record of our Public Warrants. The actual number of stockholders of our common stock is greater than this number of record holders and includes stockholders who are beneficial owners but whose shares of common stock are held in street name by banks, brokers and other nominees.

Dividend Policy

We have not paid any cash dividends on the common stock to date. We have no current plans to pay cash dividends for the foreseeable future. Any decision to declare and pay dividends in the future will be made at the discretion of the Board and will depend on, among other things, our results of operations, financial condition, cash requirements, contractual restrictions and other factors that the Board may deem relevant. In addition, our ability to pay dividends may be limited by covenants of any existing and future outstanding indebtedness we incur. We do not anticipate declaring any cash dividends to holders of the common stock in the foreseeable future.

Issuer Purchases of Equity Securities

During the year ended December 31, 2025, we did not purchase any of our equity securities that are registered under Section 12(b) of the Exchange Act (other than shares that were repurchased pursuant to net settlement to satisfy tax withholding obligations of plan participants upon the vesting of restricted stock unit awards).

Investor Relations Agreement

On December 29, 2025, we entered into an agreement with MZHCI, LLC to provide investor relations consulting services for an initial term of one year. We agreed to, among other things, issue MZHCI $199,999.92 worth of our restricted common stock, vesting in equal monthly increments over 12 months. The Company issued 9,009 shares to MZHCI on December 29, 2025 and such securities were exempt from registration under Section 4(a)(2) of the Securities Act. The Company also agreed to provide performance bonuses if certain criteria are met, in the form of cash or restricted common stock (at the discretion of the Company).

Securities Authorized for Issuance Under Equity Compensation Plans

See “Part III—Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.”

Recent Sales of Unregistered Securities

The Company had no sales of unregistered equity securities during the period covered by this Annual Report on Form 10-K that were not previously reported in a Current Report on Form 8-K or Quarterly Report on Form 10-Q.

ITEM 6. [RESERVED]

ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS.

Overview

Our long-duration iron flow batteries are the product of nearly 50 years of scientific advancement. Our founders began advancing this technology in 2011 and formed Legacy ESS. Our team has significantly enhanced the technology, improved round-trip efficiency and developed an innovative and patented solution to the hydroxide build-up problem that plagued previous researchers developing iron flow batteries. Our proprietary solution to eliminate the hydroxide formation is known as the Proton Pump, which works by utilizing hydrogen generated by side reactions on the negative electrode. The Proton Pump converts the hydrogen back into protons in the positive electrolyte. This process eliminates the hydroxide and stabilizes the electrolytes’ pH levels.

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Our batteries provide more clean energy every day to utilities, independent power producers, and commercial industrial customers, offering a path to carbon free energy supply. ESS batteries offer flexible, frequent cycling capabilities which can offer higher value clean energy when it is needed, and support a variety of grid conditions. Our technology addresses energy delivery, duration and cycle-life in a single battery platform that compares favorably to lithium-ion batteries, the most widely deployed alternative technology. Using our iron flow battery technology, we have developed a variety of products to provide reliable, safe, long-duration energy storage solutions. Our first energy storage product, the Energy Warehouse, was our ‘behind-the-meter’ solution (referring to solutions that are located on the customer’s premises, behind the service demarcation with the utility) that was used for initial testing and technology validation. Our product offering evolved to a larger scale energy storage product with the Energy Center, designed for either ‘behind-the-meter’ or ‘front-of-the-meter’ (referring to solutions that are located outside the customer’s premises, typically operated by the utility or by third-party providers who sell energy into the grid, often known as independent power producers) deployments specifically for utility and large commercial and industrial consumers, before the launch of our 10+ hour Energy Base product earlier this year. We also offer productized versions of our core technology components for integration into third-party systems.

Key Factors and Trends Affecting Our Business

We believe that our performance and future success depends on several factors that present significant opportunities for us but also pose risks and challenges, including those discussed below and in the section “Part I—Item 1A. Risk Factors” included elsewhere in this Annual Report on Form 10-K.

We believe we have the opportunity to establish attractive margin unit economics if we are able to continue to reduce production costs and scale our operations. Our future financial performance will depend on our ability to deliver on these economies of scale with lower product costs. We believe our business model is positioned for scalability due to the ability to leverage the same core technology in the Energy Base’s modularized form for different project size and duration needs across our customer base. We anticipate significant reduction in our cost of goods through our cost reduction initiatives, including design optimization from value engineering, strategic supply chain projects, and further automation of our manufacturing processes. Additionally, significant improvements in manufacturing scale are expected to decrease the cost of materials and direct labor. We expect our indirect cost of revenue and operating expenses to increase when we ramp up our manufacturing and sales activities. We further expect an increase in expenses related to the implementation of cost reduction projects and initiatives in our supply chain, manufacturing engineering and research and development functions. Achievement of margin targets and cash flow generation is dependent on the execution of these cost out initiatives.

Our near-term and medium-term revenue is expected to be generated primarily from Energy Base and core technology component sales. We believe our unique technology provides a compelling value proposition and an opportunity for favorable margins and unit economics in the energy storage industry in the future.

Impact of Macroeconomic Developments

We are closely monitoring macroeconomic developments, including global supply chain challenges, foreign currency fluctuations, fluctuations in inflation and interest rates and monetary policy changes, as well as global events, such as the Russia-Ukraine conflict, the conflict between the U.S., Israel and Iran, geopolitical tensions involving China, tensions in the Middle East, U.S. interventions in Venezuela, and other areas of geopolitical tension around the world, and how they may adversely impact our and our customers’, contractors’, suppliers’ and partners’ respective businesses. In particular, weak economic conditions or significant uncertainty regarding the stability of financial markets related to stock market volatility, inflation, recession, governmental fiscal, monetary and tax policies, or tariffs and trade restrictions, among others, could adversely impact our and our customers’ business, financial condition and operating results. While the Company has not experienced any significant impacts from these disruptions to date, future impacts are unknown and they could adversely affect our business, supply chain, partners or customers.

In addition, general and ongoing tightening in the credit market, lower levels of liquidity, increases in rates of default and bankruptcy, and significant volatility in equity and fixed-income markets could all negatively impact our customers, contractors, suppliers and partners. As a result of these macroeconomic forces, during 2024 and 2025 we experienced supply constraints, increased shipping delays for certain customer contracts, and delays in timing of payments from some of our customers. Some or all of these negative trends may continue into 2026.

To the extent that challenging macroeconomic conditions persist, we may experience an extension and worsening of these effects as well as additional adverse effects on our business, financial condition, or results of operations in future periods. These effects could include, among others, slower purchasing decisions by existing and potential new customers, additional delays in timing of payments under our existing customer contracts, further reduction or delays in purchasing decisions by our customers, potential losses of customers as a result of economic distress or bankruptcy, and increased costs for raw materials and freight resulting from inflationary cost pressures.

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For further discussion of the challenges and risks we confront related to macroeconomic conditions and geopolitical tension around the world, please refer to “Part I—Item 1A. Risk Factors” of this Annual Report on Form 10-K.

Impact of Legislative Developments

On August 16, 2022, the President of the United States signed into law the IRA, which extended the availability of ITCs and PTCs and made significant changes to the tax credit regime that applies to solar and energy storage products. As a result of changes made by the IRA, the ITC for solar generation projects was extended until at least 2033 and expanded to include stand-alone battery storage projects. This expansion provided more certainty on the tax incentives available to stand-alone battery storage projects in the future. Subject to recently enacted legislation discussed above, we believe the IRA will increase demand for our services due to the extensions and expansions of various tax credits that are critical for our customers’ economic returns, while also providing more certainty in and visibility into the supply chain for materials and components for energy storage systems. On July 4, 2025, the OBBB was signed into law by the President of the United States. The OBBB contains a number of changes to the IRA that significantly impact the availability of the ITCs under Sections 48(a) and 48E of the Code and Section 45X PTCs as discussed further above, but the Company’s domestic manufacturing and supply chain structure generally should benefit from the addition of FEOC limitations, subject to our review of recently issued and future FEOC guidance. We are continuing to evaluate the overall impact and applicability of the IRA and OBBB as guidance is issued and further legislative changes are enacted, including the passage of comparable legislation in other jurisdictions, to our results of operations going forward.

As discussed in Note 17, Government Grants, to our consolidated financial statements, Section 45X of the Code, as enacted by the IRA, currently provides a PTC that can be claimed on certain battery components manufactured in the U.S. and sold to unrelated U.S. or foreign customers after 2022, through the end of 2032. The tax credits available to manufacturers include a credit for ten percent of the cost incurred to make electrode active materials in addition to credits of $35 per kWh of capacity for battery cells and $10 per kWh of capacity for battery modules. The credits are cumulative, meaning that companies will be able to claim each of the available tax credits based on the battery components produced and sold through 2029, after which the PTC will begin to gradually phase down through the end of 2032, subject to additional qualification requirements in the recently enacted OBBB as discussed further above, including qualifications for integrated components sold after December 31, 2026 to the effect that any primary component integrated into a secondary component must be produced within the same manufacturing facility, at least 65 percent of the total direct material costs of the secondary component must be attributable to primary components which are domestically mined, produced or manufactured, and the secondary component must be sold to a third party. The Section 45X PTC may be refundable by the IRS or saleable to unrelated third parties. We continue to evaluate the impact of the OBBB; however, we generally expect to sell these credits to third party buyers, which will have a positive impact on our gross margins in the future. Further, on October 28, 2024, Treasury and the IRS issued final regulations providing guidance on requirements that taxpayers must satisfy to qualify for the Section 45X PTC, including the definition of a Section 45X manufacturing facility.

Components of Results of Operations

Revenue and Cost of revenue

We earn revenue from the sale of our energy storage products and from service contracts. Revenue from service contracts includes engineering design and extended warranty and maintenance services for our energy storage products. We invoice our customers based upon contractual terms, and accordingly, we have deferred revenues and contract assets depending upon whether we can invoice in advance of satisfying the performance obligations under the respective customer contract or in arrears, respectively. As we are a project-based business, there is inherent variability in our revenue due to variations in pricing, project complexity and timing of delivery across customer projects. Additionally, increased regulatory uncertainty may create a more challenging customer environment and have significant impacts on the consistency and predictability of our revenue year-over-year.

Cost of revenue is primarily driven by direct material, labor, freight and overhead expenses. Cost of revenue also includes LCNRV charges, warranty costs, losses on unfulfilled noncancellable purchase commitments, obsolescence charges, and fulfillment costs. Cost of revenue does not include inventory previously expensed during the research and development phase of accounting which we transitioned out of in the third quarter of 2023. We expect revenue and cost of revenue to increase when we scale the business and deliver our energy storage products to customers.

Operating expenses

Research and development

Research and development expenses consist of materials, supplies, personnel-related expenses, consulting services and other direct expenses. Personnel-related expenses consist of salaries, bonuses, benefits and stock-based compensation. We continue to perform research and development activities to further expand our product roadmap.

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Sales and marketing

Sales and marketing expenses consist primarily of salaries, bonuses, benefits and stock-based compensation for marketing and sales personnel and related support teams. To a lesser extent, sales and marketing expenses also include professional services costs, travel costs, and trade show sponsorships. We expect that our sales and marketing expenses will increase over time as we continue to hire additional personnel to scale our business.

General and administrative

General and administrative expenses consist of personnel-related expenses for our corporate, executive, finance, legal, and other administrative functions, as well as expenses for outside professional services and insurance costs. Personnel-related expenses consist of salaries, bonuses, benefits and stock-based compensation. To a lesser extent, general and administrative expenses include depreciation and other allocated costs, and supplies. We expect some of our general and administrative expenses to increase as we expand our operations and manufacturing capacity to support the growth of our business, and as a result of operating as a public company, including compliance with the rules and regulations of the SEC, legal, audit, additional insurance expenses, investor relations activities, and other administrative and professional services.

Other (expense) income, net

Interest (expense) income, net

Interest (expense) income, net consists primarily of interest expense on the Promissory Note and our sale-leaseback financing obligation and earned income on our cash equivalents, restricted cash, and short-term investments. These earned income amounts will vary based on our cash, cash equivalents, restricted cash and short-term investment balances, and on market rates.

Gain on revaluation of common stock warrant liabilities

Gain on revaluation of common stock warrant liabilities consists of periodic fair value adjustments related to our common stock warrants.

Other expense, net

Other expense, net consists primarily of various gains and losses associated with our short-term investments and other income and expense items.

Results of Operations

In this section, we discuss the results of our operations for the year ended December 31, 2025 compared to the year ended December 31, 2024.

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Comparison of Year Ended December 31, 2025 to Year Ended December 31, 2024

The following table sets forth ESS’ operating results for the periods indicated:


	Year Ended December 31,
($ in thousands)	2025		2024		$ Change		% Change
Revenue	$	1,583	$	6,295	$	(4,712)	(75)%
Cost of revenue	29,255		51,653		(22,398)		(43)
Gross loss	(27,672)		(45,358)		17,686		(39)
Operating expenses
Research and development	8,297		11,772		(3,475)		(30)
Sales and marketing	3,834		9,161		(5,327)		(58)
General and administrative	17,604		23,507		(5,903)		(25)
Total operating expenses	29,735		44,440		(14,705)		(33)
Loss from operations	(57,407)		(89,798)		32,391		(36)
Other (expense) income, net
Interest (expense) income, net	(5,455)		3,574		(9,029)		(253)
Gain on revaluation of common stock warrant liabilities	229		115		114		99
Other expense, net	(807)		(113)		(694)		614
Total other (expense) income, net	(6,033)		3,576		(9,609)		(269)
Net loss and comprehensive loss to common stockholders	$	(63,440)	$	(86,222)	$	22,782	(26)%

Revenue

Revenue for the year ended December 31, 2025 was $1.6 million compared to $6.3 million for the year ended December 31, 2024. During the year ended December 31, 2025, we delivered and recognized revenue for both completed and in-process Energy Warehouses, Energy Centers, and other related equipment, primarily to related parties, and recognized revenue for engineering services related to a product site deployment and extended warranty services. Revenue recognized was partially offset by activities related to the wind down of active contracts for legacy business activities in connection with the shift to the Energy Base product offering, which included certain limited agreements with customers to settle all outstanding obligations and which resulted in reductions to revenue. During the year ended December 31, 2024, we recognized revenue for a higher volume of sales of Energy Centers, Energy Warehouses, other related equipment, engineering services related to a product site deployment, and extended warranty services.

Cost of revenue

Cost of revenue decreased by $22.4 million, or 43%, from $51.7 million for the year ended December 31, 2024 to $29.3 million for the year ended December 31, 2025 as a direct result of the implementation of product cost-saving initiatives, reduced personnel-related expenses, lower levels of production, and fewer deliveries of equipment to customers. We also recognized a decrease in warranty expense as existing warranties expired. These benefits realized were partially offset by write-offs of obsolete and excess inventory related to the transition to the Energy Base product offering.

Operating expenses

Research and development expenses

Research and development expenses decreased by $3.5 million, or 30%, from $11.8 million for the year ended December 31, 2024 to $8.3 million for the year ended December 31, 2025. The decrease resulted from reduced personnel-related expenses, including stock-based compensation, reduced purchases of testing equipment and supplies, and decreased outside services expenses, mitigated by a $1.7 million abandonment charge recognized related to the Company’s patent portfolio as a result of management’s assessment of the expected viability and usefulness of the underlying patents given the current technologies and product offering in development.

Sales and marketing expenses

Sales and marketing expenses decreased by $5.3 million, or 58%, from $9.2 million for the year ended December 31, 2024 to $3.8 million for the year ended December 31, 2025. The decrease is driven by reduced personnel-related expenses, including stock-based compensation, decreased outside services and professional expenses, and decreased marketing and trade show expenses.

General and administrative expenses

General and administrative expenses decreased by $5.9 million, or 25%, from $23.5 million for the year ended December 31, 2024 to $17.6 million for the year ended December 31, 2025. The decrease is driven by decreased personnel-

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related expenses, including stock-based compensation expense, as a result of reduced executive compensation, decreased IT expenses and decreased insurance fees, partially offset by increased professional and outside services costs.

Other (expense) income, net

Interest (expense) income, net

Interest (expense) income, net increased by 253% to a net expense position of $5.5 million for the year ended December 31, 2025 compared to $3.6 million of interest income for the year ended December 31, 2024. The change resulted from interest incurred on the Promissory Note and the sale-leaseback financing obligation compounded by a decrease in interest income earned on our short-term investment portfolio due to lower investment balances.

Gain on revaluation of common stock warrant liabilities

The change in fair value of common stock warrant liabilities resulted in a gain of $0.2 million and $0.1 million for the years ended December 31, 2025 and 2024, respectively. The changes in fair value of common stock warrant liabilities were driven by changes in the market price of our common stock over the respective period.

Other expense, net

Other expense, net increased by $0.7 million, from $0.1 million for the year ended December 31, 2024 to $0.8 million for the year ended December 31, 2025. The increase was due to discount expenses incurred in the year ended December 31, 2025 related to sales made under the SEPA.

Liquidity and Capital Resources

Since our inception, we have financed our operations primarily through the issuance and sale of equity and debt securities and loan agreements. We have incurred losses since inception and have negative cash flows from operations. We anticipate that losses will continue in the near term. During the year ended December 31, 2025, we incurred net losses of $63.4 million and used $50.3 million of cash in operating activities. As of December 31, 2025, we had unrestricted cash and cash equivalents of $14.5 million and short-term investments of $7.5 million, or total liquid assets of $22.0 million. We have expanded certain cost reduction and cash conservation measures, including ongoing evaluation of workforce staffing requirements and essential business functions, and the implementation of a furlough for a substantial number of our employees as of May 30, 2025 to better align organizational costs with business continuity, further reduction of material purchases by continuing to minimize spending until firm orders are received, refining our focus on research and development and engineering project efforts towards highest priority, greatest return projects and additional reduction in outside vendor spending.

Despite the cost reductions and cash conservation measures, we will need additional debt or equity financing in order to meet our near-term operating cash flow requirements, and accordingly substantial doubt exists as to our ability to continue as a going concern for 12 months from the issuance of the consolidated financial statements included in this Annual Report on Form 10-K. We have based our near-term operating cash flow requirements on certain assumptions, including that usage in 2025 is predictive of needs in 2026, vendors will continue to be cooperative with respect to payment plans for outstanding invoices, and no significant additional severance costs or other unanticipated contingencies will arise. These assumptions may be inaccurate, and we may use our available capital resources sooner than we currently expect. In addition, we may not be successful in raising additional funds.

Management has taken a variety of steps to mitigate costs, reduce operating expenses and extend our runway while we are evaluating various strategies to obtain additional funding, which may include additional offerings of equity, issuance of debt, or other capital sources. If such financing is not available or if the financing terms are less desirable than we expect, we may be forced to decrease our level of investment in product development or further scale back our operations, which could have an adverse impact on our business and financial prospects.

We have a standby letter of credit with Bank of America for $0.6 million as security for the performance and payment of our obligations under a customer agreement. The letter of credit is in effect until the date on which the warranty period under the agreement expires, which is anticipated to be more than a year from the balance sheet date. As of December 31, 2025, $0.6 million was pledged as collateral for the letter of credit and recorded as restricted cash, non-current. There were no draws against the letter of credit during the years ended December 31, 2025 and 2024.

We have a standby letter of credit with Bank of America for $0.2 million in support of our customs and duties due on imported materials. The letter of credit is in effect until May 19, 2026. As of December 31, 2025, $0.1 million was pledged as collateral for the letter of credit and recorded as restricted cash, current. There were draws of $0.1 million against the letter of credit during the year ended December 31, 2025.

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On November 1, 2024, we entered into a Credit Agreement with Export-Import Bank of the United States, as lender, and related agreements related to the financing of two production lines (the “Credit Agreement”). The Credit Agreement provides for a secured loan facility in an aggregate principal amount of up to $22.7 million, of which $20.0 million is available to be borrowed for equipment financing and the balance will be used to finance an exposure fee and transaction expenses. The loan facility has a maturity date of June 30, 2031. Half of the proceeds of the loan facility may be used on a retroactive basis for the financing of our existing automated battery assembly line and the remainder may be used for the financing or refinancing of an additional line upon the closing of an equity raise milestone. As of December 31, 2025 we had no outstanding borrowings under the Credit Agreement. Any obligations under the Credit Agreement are secured pursuant to a security agreement granting EXIM a first priority security interest in the financed equipment and a securities account containing collateral consisting of cash and cash equivalents in an amount equal to a substantial portion of the disbursements under the Credit Agreement, reportable as restricted cash, that decreases upon the equity raise milestone. See Note 11, Commitments and Contingencies, to our financial statements included elsewhere in this Annual Report on Form 10-K for further discussion.

We also maintain a shelf registration statement on Form S-3 pursuant to which we may, from time to time, sell up to an aggregate of $300 million of our common stock, preferred stock, debt securities, depositary shares, warrants, subscription rights, purchase contracts, or units.

On March 31, 2025, we entered into an at-the-market sales agreement with Baird, pursuant to which we sold 616,264 shares for total proceeds, net of commission fees, of $0.7 million. On July 11, 2025, we terminated our continuous offering under the prospectus supplement dated March 31, 2025 related to the at-the-market offering and on November 10, 2025, we terminated the sales agreement.

On July 9, 2025, we entered into the SEPA with Yorkville, pursuant to which the Investor purchased shares of our common stock in increments up to an aggregate gross sales price of up to $25 million. The shares were sold at our option pursuant to the SEPA at 97% of the Market Price (as defined in the SEPA). As of October 21, 2025, we completed the offering under the SEPA, having sold an aggregate of 6,458,634 shares under the SEPA for total proceeds of $25 million.

On October 14, 2025, we entered into an unsecured promissory note with the Investor in the aggregate principal amount of up to $40 million (the “Promissory Note”), in two tranches consisting of a first tranche of $30 million and a second tranche of $10 million, in each case less an original issue discount of 8% and certain fees and expenses. The Promissory Note accrues interest at a rate of 3% per annum and matures on October 14, 2026. On November 12, 2025, we entered into an amendment to the Promissory Note with the Investor, amending the repayment schedule of the Promissory Note such that monthly payments would begin on December 15, 2025. On December 4, 2025, we entered into a second amendment to the Promissory Note with the Investor, amending the second tranche date from December 12, 2025 to February 28, 2026, extending the deadline by which the Investor shall pay the second tranche of $10 million less the applicable discount. As of the date of this report, we have repaid $28 million of the principal amount of the initial $30 million Promissory Note.

On November 13, 2025, in connection with an “at the market offering” program, we entered into a Sales Agreement (the “Sales Agreement”) with Yorkville Securities, LLC (“Yorkville”), BMO Capital Markets Corp., Canaccord Genuity LLC, Needham & Company, LLC and Stifel, Nicolaus & Company, Incorporated (the “Agents”) pursuant to which we may sell, from time to time, shares of our common stock during the term of the Sales Agreement, through the Agents acting either as agent or principal. We filed a prospectus supplement with the SEC relating to the offer and sale of our common stock having an aggregate gross sales price of up to $75 million pursuant to the Sales Agreement. We intend to use the net proceeds from the offering, if any, in compliance with the terms of the Promissory Note, which generally requires that proceeds first be used to satisfy any installment payments under the Promissory Note due within thirty days. After any such payments, 80% of the remaining proceeds from this offering will be used to satisfy installment payments under the Promissory Note in direct order of maturity until the promissory note is repaid in full. In respect of the remaining 20% of proceeds that we may receive while the Promissory Note is outstanding, and all net proceeds we may receive following the repayment of the Promissory Note, we intend to use such net proceeds for working capital and general corporate purposes.

On January 29, 2026, the Company signed a securities purchase agreement with institutional investors pursuant to which the Company agreed to issue and sell in a registered direct offering registered under the Securities Act, an aggregate of 3,471,428 shares of common stock, Pre-Funded Warrants to purchase an aggregate of 5,100,000 shares of common stock at an exercise price of $0.00001 per share, and the 5,100,000 shares of common stock underlying the Pre-Funded Warrants at an offering price of $1.75 per Share or $1.74999 per Pre-Funded Warrant, as applicable (the “Registered Direct Offering,” or “RDO”). The Registered Direct Offering closed on January 30, 2026. The net proceeds of the RDO were approximately $14 million, after deducting placement agent fees and expenses and other estimated offering expenses payable by the Company.

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The following table summarizes cash flows from operating, investing and financing activities for the periods presented (in thousands):


	Years Ended December 31,
	2025		2024
Net cash used in operating activities	$	(50,284)	$	(72,219)
Net cash provided by investing activities	7,528		64,757
Net cash provided by financing activities	43,462		174

Cash flows from operating activities:

Cash flows used in operating activities to date have primarily consisted of inventory purchases and cost of revenue, costs related to research and development of our energy storage systems, building awareness of our products’ capabilities and other general and administrative activities.

Net cash used in operating activities was $50.3 million for the year ended December 31, 2025, which is comprised of net loss of $63.4 million, partially offset by depreciation expense of $5.7 million, stock-based compensation of $5.4 million, and non-cash interest expense of $5.0 million. Net changes in operating assets and liabilities used $6.4 million of cash, driven by decreases in accounts payable, accrued and other current liabilities, deferred revenue, accrued product warranties, and operating lease liabilities and partially offset by reductions in inventory and prepaid expenses and cash collections on accounts receivable.

Net cash used in operating activities was $72.2 million for the year ended December 31, 2024, which is comprised of net loss of $86.2 million, adjusted for noncash interest income of $2.4 million, partially offset by stock-based compensation of $11.6 million and depreciation expense of $4.7 million. Net changes in operating assets and liabilities used $1.6 million of cash driven by inventory purchases, an increase in prepaid and other current assets, and decreases in accrued and other current liabilities, operating lease liabilities, and deferred revenue, offset by increases in accounts payable and accrued product warranties and cash collections on accounts receivable.

Cash flows from investing activities:

Our cash flows from investing activities have been comprised primarily of purchases and sales of short-term investments and purchases of property and equipment.

Net cash provided by investing activities was $7.5 million for the year ended December 31, 2025, which related to maturities of short-term investments partially offset by purchases of property and equipment.

Net cash provided by investing activities was $64.8 million for the year ended December 31, 2024, which related to maturities of short-term investments partially offset by purchases of property and equipment.

Cash flows from financing activities:

Cash flows from financing activities to date have consisted of the Business Combination, our partnership with Honeywell, and the issuance of debt and equity securities and loan agreements.

Net cash provided by financing activities was $43.5 million for the year ended December 31, 2025 and consisted of proceeds from the issuance of common stock and common stock warrants, net of issuance costs of $37.7 million and proceeds from financing arrangements of $27.0 million, partially offset by payments on financing obligations of $21.0 million.

Net cash provided by financing activities was $0.2 million for the year ended December 31, 2024 and consisted of proceeds from contributions to our ESPP of $0.4 million and stock options exercised of $0.1 million, partially offset by repurchases of shares from employees for income tax withholding purposes of $0.3 million.

Further commercialization, development, and expansion of our business will require a significant amount of cash for expenditures. Our ability to successfully manage this growth will depend on many factors, including our working capital needs, the availability of equity or debt financing and, over time, our ability to generate cash flows from operations.

Contractual Obligations and Commitments

Our contractual obligations and other commitments as of December 31, 2025 consist of lease commitments and two standby letters of credit and the Credit Agreement. The letters of credit serve as security for our performance and payment obligations under a customer agreement and in support of our customs and duties due on imported materials and are secured by a total of $0.7 million pledged as collateral. Our obligations under the Credit Agreement are secured pursuant to a security agreement granting EXIM a first priority security interest in the financed equipment and a securities account

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containing collateral consisting of cash and cash equivalents in an amount equal to a certain portion of the disbursements under the Credit Agreement that decreases upon the equity raise milestone and will be reported as restricted cash. There were draws of $0.1 million against the letter of credit supporting our customs and duties due on imported materials during the year ended December 31, 2025 and no draws against other letters of credit or under the Credit Agreement during the years ended December 31, 2025 or 2024. Additionally, we are committed to non-cancellable purchase commitments of $0.1 million as of December 31, 2025 and to reimburse UOP a minimum of $8.0 million for research and development expenses incurred through December 31, 2028 under the JDA (as defined herein).

Off-Balance Sheet Arrangements

We are not a party to any off-balance sheet arrangements, including guarantee contracts, retained or contingent interests, or unconsolidated variable interest entities that either have, or are reasonably likely to have, a current or future material effect on our financial statements.

Critical Accounting Policies and Estimates

The preparation of financial statements in conformity with U.S. GAAP requires that management apply accounting policies and make estimates and assumptions that affect amounts reported in the statements. The following accounting policies represent those that management believes are particularly important to the financial statements and that require the use of estimates, assumptions, and judgments to determine matters that are inherently uncertain.

Inventory Valuation

Inventory is stated on a first-in, first-out basis at the lower of cost or net realizable value. Net realizable value is the estimated selling price of inventory in the ordinary course of business, less estimated costs of completion, disposal, and transportation. We periodically make judgments and estimates regarding the future utility and carrying value of inventory. When inventory is adjusted to its net realizable value, a new cost basis is established and such cost is not adjusted for any potential recovery or increase in cost. Obsolete inventories are written off to cost of revenue. Should our estimates of future selling prices or production costs change, additional and potentially material write-downs may be required. A small change in our estimates may result in a material charge to our reported financial results.

Revenue Recognition

Revenue is earned from the sales of energy storage systems and related services and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which we expect to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as our performance obligations are satisfied which includes estimates for variable consideration. For sales of energy storage systems, our performance obligations are satisfied at the point in time when the customer obtains control of the system.

Payment terms generally include advance payments to reserve capacity and/or material procurement or commence upon issuance of the customer’s purchase order with the remainder due upon the achievement of various milestones including shipment readiness, delivery, system start up, and/or completion of final site testing.

The transaction price of the underlying customer agreement is allocated to each performance obligation based on its relative standalone selling price. When the standalone selling price is not directly observable, revenue is determined based on an estimate of selling price using the observable market price that the good or service sells for separately in similar circumstances and to similar customers, and/or an expected cost plus margin approach when the observable selling price of a good or services is not known and is either highly variable or uncertain.

Recently Issued Accounting Standards

See Note 2, Significant Accounting Policies to our financial statements for the year ended December 31, 2025 included elsewhere in this Annual Report on Form 10-K.

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

We are a smaller reporting company as defined by Rule 12b-2 of the Exchange Act and are not required to provide the information otherwise reported under this Item.

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ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

The following financial statements and report are included in Item 8:


			Page
Report of Independent Registered Public Accounting Firm			58
Financial Statements
Consolidated Balance Sheets			60
Consolidated Statements of Operations and Comprehensive Loss			61
Consolidated Statements of Stockholders’ Equity			62
Consolidated Statements of Cash Flows			63
Notes to Consolidated Financial Statements			65

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REPORT OF KPMG LLP

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Stockholders and the Board of Directors

ESS Tech, Inc.:

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of ESS Tech, Inc. (the Company) as of December 31, 2025 and 2024, the related consolidated statements of operations and comprehensive loss, stockholders’ equity, and cash flows for each of the years in the two-year period ended December 31, 2025, and the related notes (collectively, the consolidated financial statements). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the years in the two-year period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles.

Going Concern

The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the consolidated financial statements, the Company has recurring net losses from operations and is generating negative cash flows from operating activities which raise substantial doubt about its ability to continue as a going concern. Management’s plans in regard to these matters are also described in Note 1. The consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these consolidated financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of a critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Liquidity and Going Concern

As discussed in Note 1 to the consolidated financial statements, the Company has incurred operating losses and cash outflows from operations since inception, and the Company anticipates that losses will continue in the near term. During the year ended December 31, 2025, the Company incurred net losses of $63.4 million and used $50.3 million of cash in operating activities. As of December 31, 2025, the Company had unrestricted cash and cash equivalents of $14.5 million and short-term investments of $7.5 million. The continuation of the Company as a going concern is dependent upon its ability to obtain additional debt or equity financing and to generate profit from its operations. Any

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such financing activities are subject to market conditions and accordingly involve factors that are outside the Company’s control. These uncertainties cause substantial doubt to exist as to the Company’s ability to continue as a going concern for 12 months from the issuance of the financial statements.

We identified the evaluation of the Company's ability to continue as a going concern and related disclosures as a critical audit matter. A high degree of subjective auditor judgment and increased audit effort was required to evaluate the Company’s going concern analysis and the adequacy of the financial statement disclosures related to the going concern assessment.

The following are the primary procedures we performed to address this critical audit matter. We obtained the Company’s going concern analysis and evaluated whether the analysis and conclusions reached comply with relevant accounting literature. We assessed the conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern. We inquired of executive officers and key members of management of the Company regarding factors that would have an impact on the Company’s ability to continue as a going concern, including the need for additional financing given the Company’s projected monthly cash outflows. We obtained and read the agreements related to the Company’s outstanding financing obligations, including subsequent events. We assessed the Company’s disclosures related to its going concern assessment by comparing the disclosures to the audit evidence obtained.

/s/ KPMG LLP

We have served as the Company’s auditor since 2023.

Portland, Oregon

March 5, 2026

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ESS Tech, Inc.

Consolidated Balance Sheets

(in thousands, except share data)


	December 31, 2025		December 31, 2024
Assets
Current assets:
Cash and cash equivalents	$	14,477	$	13,341
Restricted cash, current	806		906
Accounts receivable, net	13		215
Short-term investments	7,557		18,263
Inventory	140		5,641
Prepaid expenses and other current assets	3,254		4,998
Total current assets	26,247		43,364
Property and equipment, net	17,224		20,582
Intangible assets, net	2,682		4,656
Operating lease right-of-use assets	3,767		1,503
Restricted cash, non-current	618		948
Other non-current assets	634		760
Total assets	$	51,172	$	71,813
Liabilities and stockholders’ equity
Current liabilities:
Accounts payable	$	3,023	$	8,070
Accrued and other current liabilities	11,097		9,315
Accrued product warranties	985		3,288
Operating lease liabilities, current	1,784		1,692
Deferred revenue, current	359		5,237
Financing obligations, current	8,044		—
Total current liabilities	25,292		27,602
Operating lease liabilities, non-current	2,060		—

Deferred revenue, non-current - related parties	5,297		14,400
Common stock warrant liabilities	573		802
Financing obligations, non-current	9,291		—
Other non-current liabilities	41		125
Total liabilities	42,554		42,929
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock ($0.0001 par value; 200,000,000 shares authorized, none issued and outstanding as of December 31, 2025 and 2024)	—		—
Common stock ($0.0001 par value; 1,000,000,000 shares authorized, 22,377,003 and 11,986,516 shares issued and outstanding as of December 31, 2025 and 2024, respectively)	2		1
Additional paid-in capital	854,435		811,262
Accumulated deficit	(845,819)		(782,379)
Total stockholders’ equity	8,618		28,884
Total liabilities and stockholders’ equity	$	51,172	$	71,813
See accompanying notes to financial statements

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ESS Tech, Inc.

Consolidated Statements of Operations and Comprehensive Loss

(in thousands, except share and per share data)


	Years Ended December 31,
	2025		2024
Revenue:
Revenue	$	(796)	$	5,712
Revenue - related parties	2,379		583
Total revenue	1,583		6,295
Cost of revenue	29,255		51,653
Gross loss	(27,672)		(45,358)
Operating expenses
Research and development	8,297		11,772
Sales and marketing	3,834		9,161
General and administrative	17,604		23,507
Total operating expenses	29,735		44,440
Loss from operations	(57,407)		(89,798)
Other (expense) income, net
Interest (expense) income, net	(5,455)		3,574
Gain on revaluation of common stock warrant liabilities	229		115
Other expense, net	(807)		(113)
Total other (expense) income, net	(6,033)		3,576
Net loss and comprehensive loss to common stockholders	$	(63,440)	$	(86,222)

Net loss per share - basic and diluted	$	(4.34)	$	(7.32)

Weighted average shares used in per share calculation - basic and diluted	14,601,626		11,773,596

See accompanying notes to financial statements

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ESS Tech, Inc.

Consolidated Statements of Stockholders’ Equity

(in thousands, except share data)


	Common Stock			Additional Paid-In Capital		Accumulated Deficit		Total Stockholders’ Equity
	Shares	Amount
Balance as of December 31, 2023	11,614,127	$	1	$	799,513	$	(696,157)	$	103,357
Issuance of common stock under stock-based compensation plans, net of stock withheld for taxes	372,389	—		174		—		174
Stock-based compensation expense	—	—		11,575		—		11,575
Net loss	—	—		—		(86,222)		(86,222)
Balance as of December 31, 2024	11,986,516	$	1	$	811,262	$	(782,379)	$	28,884
Issuance of common stock under stock-based compensation plans, net of stock withheld for taxes	510,308	—		140		—		140
Issuance of common stock under the SEPA and ATM, net of issuance costs	9,880,179	1		32,966		—		32,967
Issuance of common stock warrants	—	—		4,633		—		4,633
Stock-based compensation expense	—	—		5,434		—		5,434
Net loss	—	—		—		(63,440)		(63,440)
Balance as of December 31, 2025	22,377,003	$	2	$	854,435	$	(845,819)	$	8,618

See accompanying notes to financial statements

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ESS Tech, Inc.

Consolidated Statements of Cash Flows

(in thousands)


	Years Ended December 31,
	2025		2024
Cash flows from operating activities:
Net loss	$	(63,440)	$	(86,222)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,740		4,724
Asset abandonment	1,707		—
Non-cash interest (income) expense	4,981		(2,422)
Non-cash lease expense	1,526		1,350
Stock-based compensation expense	5,434		11,575
Change in fair value of common stock warrant liabilities	(229)		(115)
Other non-cash (income) expenses, net	388		459
Changes in operating assets and liabilities:
Accounts receivable, net	202		1,549
Inventory	4,833		(3,326)
Prepaid expenses and other assets	1,870		(1,620)
Accounts payable	(3,842)		4,243
Accrued and other liabilities	(2,841)		(1,123)
Accrued product warranties	(2,303)		1,159
Deferred revenue	(2,672)		(918)
Operating lease liabilities	(1,638)		(1,532)
Net cash used in operating activities	(50,284)		(72,219)

Cash flows from investing activities:
Purchases of property and equipment	(3,387)		(7,294)
Maturities and purchases of short-term investments, net	10,915		72,051
Net cash provided by investing activities	7,528		64,757

Cash flows from financing activities:
Proceeds from issuance of common stock and common stock warrants, net of issuance costs	37,651		—
Proceeds from financing arrangements	27,028		—
Debt issuance costs	(308)		—
Payments on financing obligations	(21,049)		—
Proceeds from stock options exercised	83		86
Repurchase of shares from employees for income tax withholding purposes	(50)		(297)
Proceeds from contributions to Employee Stock Purchase Plan	107		385
Net cash provided by financing activities	43,462		174

Net change in cash, cash equivalents and restricted cash	706		(7,288)
Cash, cash equivalents and restricted cash, beginning of period	15,195		22,483
Cash, cash equivalents and restricted cash, end of period	$	15,901	$	15,195

See accompanying notes to financial statements

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ESS Tech, Inc.

Consolidated Statements of Cash Flows (continued)

(in thousands)


	Years Ended December 31,
	2025		2024
Supplemental disclosures of cash flow information:
Cash paid during the year for:
Operating leases included in cash used in operating activities	$	1,776	$	1,738
Interest	520		—

Non-cash investing and financing transactions:
Purchase of property and equipment included in accounts payable and accrued and other current liabilities	28		1,586
Adjustment to right-of-use assets from lease modification	3,790		686
Transfers between inventory and property and equipment, net	668		1,051
Application of deferred revenue to financing obligations	6,518		—

Cash and cash equivalents	$	14,477	$	13,341
Restricted cash, current	806		906
Restricted cash, non-current	618		948
Total cash, cash equivalents and restricted cash	$	15,901	$	15,195

See accompanying notes to financial statements

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ESS TECH, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.DESCRIPTION OF BUSINESS, BASIS OF PRESENTATION AND CONSOLIDATION, AND RISKS AND UNCERTAINTIES

Description of Business—ESS Tech, Inc. (“ESS” or the “Company”) is a long-duration energy storage company specializing in iron flow battery technology. ESS develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring up to twelve hours of flexible energy capacity predominantly using earth-abundant materials.

The Company was founded in 2011 (“Legacy ESS”) and became a publicly traded company through a business combination with a special purpose acquisition company named ACON S2 Acquisition Corp. (“STWO”) which changed its name to ESS Tech, Inc. upon closing (the “Business Combination”). As a result of the Business Combination, Legacy ESS survived and became a wholly owned subsidiary of ESS Tech, Inc. On March 31, 2024, Legacy ESS merged with ESS Tech, Inc. leaving ESS Tech, Inc. as the sole remaining legal entity.

Basis of Presentation—The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Basis and Principles of Consolidation—The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Project New Horizon, LLC, which was formed in October of 2025 and is wholly owned and controlled by the Company. The subsidiary and its activity is immaterial to the results and financial position of the Company as of December 31, 2025. All intercompany accounts and transactions have been eliminated upon consolidation.

Risks and Uncertainties—The Company is subject to a number of risks associated with companies of similar size in its industry, including, but not limited to, the need for successful development of products, the need for additional capital and financing to fund operations, competition from substitute products and services from larger companies, legal protection of proprietary technology, patent litigation, dependence on key individuals, and risks associated with changes in information technology.

Concentration of Credit Risk—Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and restricted cash. The Company’s cash and cash equivalents include cash in bank accounts, money market funds, and investments with a maturity of three months or less at the date of purchase. The Company’s restricted cash includes collateral associated with a standby letter of credit and a performance and payment bond. Deposits held with banks may exceed the amount of insurance provided on such deposits.

Liquidity and Capital Resources—The Company has incurred operating losses and cash outflows from operations since inception and the Company anticipates that losses will continue in the near term. During the year ended December 31, 2025, the Company incurred net losses of $63.4 million and used $50.3 million of cash in operating activities. As of December 31, 2025, the Company had unrestricted cash and cash equivalents of $14.5 million and short-term investments of $7.5 million, or total liquid assets of $22.0 million.

The continuation of the Company as a going concern is dependent upon its ability to obtain additional debt or equity financing and to generate profit from its operations. Management is evaluating various strategies to obtain additional funding, which may include additional offerings of equity, issuance of debt, or other capital sources. There is no assurance that the Company will be able to generate sufficient profits, obtain such financings at all, or obtain them on favorable terms. Any such financing activities are subject to market conditions and accordingly involve factors that are outside the Company’s control. These uncertainties cause substantial doubt to exist as to the Company’s ability to continue as a going concern for 12 months from the issuance of these financial statements. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The consolidated financial statements do not reflect any adjustments that might result from the outcome of this uncertainty.

2.SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates—The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies as of the date of the financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, but are not limited to, inventory valuation, product warranty liabilities, standalone selling prices, the fair value of the Company’s investments and warrant liabilities, the allocation of proceeds between debt and equity securities issued in conjunction with each other, the useful lives and assessment

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of recoverability of property and equipment, deferred tax assets valuation, as well as other accruals. These estimates are based on historical trends, market pricing, current events and other relevant assumptions and data points. Actual results could differ from those estimates and such differences may be material to the financial statements.

Reclassifications—Certain prior year amounts have been reclassified to conform with current year presentation, including Inventory write-down and losses on noncancellable purchase commitments separately disclosed within the Statement of Cash Flows within the 2024 Form 10-K which have been reclassified to Changes in inventory and Changes in accounts payable herein. These reclassifications had no effect on the reported results of operations.

Cash and Cash Equivalents—Cash and cash equivalents include cash in bank accounts, money market funds, and investments with a maturity of three months or less at the date of purchase. Cash equivalents are recorded at carrying value, which approximates fair value.

Restricted Cash—Restricted cash is required as collateral for certain of the Company’s contractual supply and service arrangements. Restricted cash includes collateral associated with a standby letter of credit issued to a customer, collateral associated with customs and duties due on imported materials and a performance and payment bond for the Company’s supply and service arrangements. The bond is recorded at carrying value, which approximates fair value. Restricted cash amounts are reported in the consolidated balance sheets as current or non-current depending on when the cash will be contractually released.

Accounts Receivable, Net—The Company evaluates the creditworthiness of its customers. If the collection of any specific receivable is doubtful, an allowance is recorded in the allowance for expected credit losses which is included in accounts receivable, net in the consolidated balance sheets. The Company had no allowance for expected credit losses recorded at either December 31, 2025 or 2024.

Inventory—Inventory consists of raw materials, work in progress, and finished goods, and is stated on a first-in, first-out basis at the lower of cost or net realizable value (“LCNRV”). Net realizable value is the estimated selling price of inventory in the ordinary course of business, less estimated costs of completion, disposal, and transportation. The Company periodically makes judgments and estimates regarding the future utility and carrying value of inventory. When inventory is adjusted to its net realizable value, a new cost basis is established and such cost is not adjusted for any potential recovery. Obsolete inventories are written off to cost of revenue. Should the Company’s estimates of future selling prices or production costs change, additional and potentially material write-downs may be required. A small change in the Company’s estimates may result in a material charge to its reported financial results.

Property and Equipment, Net—Property and equipment are stated at cost, net of depreciation. Depreciation is provided using the straight-line method over the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized over the lesser of the estimated useful lives of the assets or the remaining lease term. Expenditures for maintenance and repairs are expensed in the consolidated statements of operations and comprehensive loss as incurred. Expenditures which materially change capacities or extend useful lives are capitalized. When assets are retired or disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gains or losses are recognized in other income (expense), net in the consolidated statements of operations and comprehensive loss.

The Company evaluates the recoverability of property and equipment for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. The Company assesses the alternative use of an asset, the condition of the asset and the current market demand to determine if an asset is impaired.

Intangible Assets, Net—Intangible assets are stated at cost, net of accumulated amortization. Intangible assets are amortized on a straight-line basis over their expected useful lives. We perform periodic reviews of intangible assets to determine whether facts and circumstances indicate that the carrying amount may not be recoverable. These reviews can be affected by various factors, including external factors such as industry and economic trends, and internal factors such as changes in our business strategy and our forecasts for specific product lines.

Investments—Investments consist primarily of U.S. Treasury securities, U.S. agency securities, corporate debt securities, and commercial paper and are classified as trading securities as they are bought and held principally for the purpose of selling them in the near term. Trading securities are carried at fair value. Unrealized gains and losses on trading securities are included in other (expense) income, net in the consolidated statements of operations and comprehensive loss.

Financing Obligations—Financing obligations are recognized at their carrying value, less any discounts and directly attributable transaction costs which are capitalized as a contra-liability and amortized as interest expense over the expected life of the debt using the effective interest method.

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Revenue Recognition—Revenue is primarily earned from the sale, installation and commissioning of energy storage systems and is derived from customer contracts. Revenue is recognized in an amount that reflects the consideration to which the Company expects to be entitled in exchange for transferring the promised goods and/or services to the customer, when or as the Company’s performance obligations are satisfied, which includes estimates for variable consideration. For product sales of energy storage systems, the Company’s performance obligations are satisfied at the point in time when the customer obtains control of the system, based primarily on shipping terms within individual customer contracts. No right of return exists on sales of energy storage systems.

Performance obligations for services, including engineering services related to product site deployment, the optional extended warranty and ongoing operations and maintenance program provided to customers, are satisfied over time as the respective services are performed. Product site deployment revenue is recognized using the input method, which is based on the Company’s estimated costs incurred compared to total costs to complete the project.

The Company invoices customers in accordance with customer agreements, which in certain circumstances may be in advance of recognizing revenue if the Company has not satisfied the associated performance obligations. Payment terms generally include advance payments to reserve capacity and/or procure materials or upon issuance of the customer’s purchase order with the remainder due upon the achievement of various milestones including but not limited to shipment readiness, delivery, system start up, and/or completion of final site testing. Advanced customer payments and unsatisfied performance obligations are recognized as deferred revenue in the consolidated balance sheets.

Sales tax collected from customers is recorded on a net basis and therefore, not included in revenue. Sales tax is recorded as a liability until remitted to governmental authorities. Shipping and handling, freight costs and other reimbursable costs are accounted for as fulfillment activities and included in revenue.

Cost of Revenue—Cost of revenue includes the cost of the energy storage systems delivered, installed and commissioned during the year. It includes direct and indirect materials, labor costs, manufacturing overhead, including depreciation, costs of tooling and machinery, adjustments to warranty expense, LCNRV charges, unfulfilled noncancellable purchase commitment expense, shipping and logistics costs, and provisions for excess and obsolete inventory. Additionally, cost of revenue benefits from production credits earned.

Product Warranties—Warranty obligations are incurred in connection with the sale of the Company’s products. The Company generally provides a standard warranty for a period of one year and an optional extended warranty. The standard warranty is accounted for as an assurance-type warranty, which provides customers with assurance that the product complies with agreed-upon specifications and does not represent a separate performance obligation. The extended warranty is considered a service-type warranty which is a distinct service and a portion of the transaction price is allocated to that performance obligation.

Costs to provide for standard warranty obligations are estimated and recorded as a liability at the time revenue is recognized on the sale of the energy storage system. Warranty reserves include management’s best estimate of the projected costs to repair or to replace any items under warranty, which is based on various factors, including the use of actual claim data to date. Initial accruals and adjustments to warranty reserves are recorded to cost of revenue.

Sales and Marketing—Sales and marketing expenses consist primarily of salaries, benefits and stock-based compensation for marketing and sales personnel and related support teams. To a lesser extent, sales and marketing expenses also include professional services costs, travel costs, and trade show sponsorships and participation. Advertising costs are expensed as incurred.

Research and Development—Research and development costs are expensed as incurred and consist of materials, supplies, personnel-related expenses, allocated facilities costs, consulting services and other direct expenses. Personnel-related expenses consist of salaries, benefits and stock-based compensation. Substantially all of the Company’s research and development expenses are related to improving existing products and developing new products and related technologies.

General and Administrative—General and administrative expenses consist of personnel-related expenses for the Company’s corporate, executive, finance, legal, and other administrative functions, as well as expenses for outside professional services and insurance costs. Personnel-related expenses consist of salaries, benefits and stock-based

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compensation. To a lesser extent, general and administrative expenses include depreciation and other allocated costs, such as facility-related expenses and supplies.

Stock-Based Compensation—The Company measures and recognizes compensation expense for all stock-based awards based on estimated fair values on the date of the grant, recognized over the requisite service period. For awards that vest solely based on a service condition, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period. The compensation expense related to stock-based awards with performance conditions is recognized over the requisite service period when achievement of the performance conditions is probable. The compensation expense related to stock-based awards with market conditions is recognized on an accelerated attribution basis over the requisite service period identified as the derived service period over which the market conditions are expected to be achieved, and is not reversed if the market condition is not satisfied. The Company accounts for forfeitures as they occur. Stock-based awards granted to employees are primarily stock options and restricted stock units (“RSUs”).

The fair value of each stock option granted is estimated using the Black-Scholes Merton option-pricing model using the single-option award approach. The following assumptions are used in the Black-Scholes Merton option-pricing model:

Risk-Free Interest Rate—The risk-free interest rate is based on the implied yield available on the date of grant on U.S. Treasury zero-coupon bonds issued with a term that is equal to the option’s expected term at the grant date.

Expected Volatility—The Company estimates the volatility for option grants by evaluating the average historical volatility of the company’s stock price for the period immediately preceding the option grant for a term that is approximately equal to the option’s expected term.

Expected Term—The expected term for employees represents the period over which options granted are expected to be outstanding using the simplified method, as the Company’s historical share option exercise experience does not provide a reasonable basis upon which to estimate the expected term. The simplified method deems the term to be the average of the time-to-vesting and contractual life of the stock-based awards.

Dividend Yield—The Company has not declared or paid dividends to date and does not anticipate declaring dividends. As such, the dividend yield has been estimated to be zero.

Income Taxes—The Company accounts for income taxes under the asset and liability method. Under this method, deferred taxes are determined based on the temporary differences between the financial statement and tax bases of assets and liabilities using tax rates expected to be in effect during the years in which the bases differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the consolidated statement of operations and comprehensive loss in the period that includes the enactment date.

ASC 740, Accounting for Income Taxes (“ASC 740”), requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management assesses that realization is “more likely than not.” Realization of the future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. Because of the Company’s history of operating losses, management believes that recognition of the deferred tax assets arising from the above-mentioned future tax benefits is currently not likely and, accordingly, has provided a full valuation allowance for these tax benefits for the years ended December 31, 2025 and 2024.

The Company recognizes accrued interest and penalties related to unrecognized tax benefits as a component of income tax expense. No amounts were accrued for the payment of interest and penalties as of December 31, 2025 and 2024. The Company is currently not aware of any issues under review that could result in significant payments, accruals, or material deviation from its position.

Net Loss Per Share—The Company will use the two-class method when computing net loss per common share when shares are issued that meet the definition of participating securities. Under this method, net earnings are reduced by the amount of dividends declared in the current period for common stockholders and participating security holders. The remaining earnings or “undistributed earnings” are allocated between common stock and participating securities to the extent that each security may share in earnings as if all the earnings for the period had been distributed. Once calculated, the earnings per common share is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding during each year presented. Diluted loss attributable to common stockholders per common share has been computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding plus the dilutive effect of outstanding options, warrants, and RSUs during the respective periods. In cases where the Company has a net loss, no dilutive effect is shown as options, warrants, and RSUs become anti-dilutive.

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Fair Value—The Company follows ASC 820, Fair Value Measurements (“ASC 820”), which establishes a common definition of fair value to be applied when U.S. GAAP requires the use of fair value, establishes a framework for measuring fair value, and requires certain disclosures about such fair value measurements.

ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows:

Level 1: Observable inputs such as quoted prices in active markets for identical assets or liabilities to which the Company has access at a measurement date.

Level 2: Observable inputs other than Level 1 quoted prices that are observable for the asset or liability, either directly or indirectly; these include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3: Unobservable inputs for which little or no market data exists and for which the Company must develop its own assumptions regarding the assumptions that market participants would use in pricing the asset or liability, including assumptions regarding risk.

Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed.

Recent Accounting Pronouncements—Not Yet Adopted— In November 2024, the FASB issued ASU No. 2024-03, Income Statement-Reporting Comprehensive Income (Topic 220): Expense Disaggregation Disclosures. The ASU requires entities to disaggregate operating expenses into specific categories within the notes to the financial statements to provide enhanced transparency. The ASU will be effective for fiscal years beginning after December 15, 2026, with early adoption permitted, and may be applied retrospectively or prospectively. The Company is currently evaluating the effect of this new standard on the Company's disclosures.

Recently Adopted Accounting Pronouncements— In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which improves the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the effective tax rate reconciliation and income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. The Company applied the amendments prospectively for the year ended December 31, 2025, and the impact of the adoption of the amendments in this update was not material to the Company’s consolidated financial position and results of the operations for the year ended December 31, 2025, since the amendments require only enhancement of existing income tax disclosures in the footnotes to the Company’s consolidated financial statements. See Note 16, Income Taxes.

3.INVENTORY

Inventory consists of the following (in thousands):


	December 31, 2025		December 31, 2024
Raw materials	$	4,756	$	12,084
Work in process	2,403		4,521
Finished goods	—		5,639
Inventory, gross	$	7,159	$	22,244
Net realizable value adjustment	(7,019)		(16,603)
Inventory	$	140	$	5,641

The balance of the Company’s inventory was written down by $7.0 million and $16.6 million from its cost to its net realizable value as of December 31, 2025 and 2024, respectively. Additionally, the Company has LCNRV losses related to noncancellable purchase commitments which were $0.1 million and $0.2 million as of December 31, 2025 and 2024, respectively. These LCNRV losses related to noncancellable purchase commitments are reflected in the materials and related purchases component of accrued and other liabilities on the consolidated balance sheets. For further details, refer to Note 11, Commitments and Contingencies.

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4.PREPAID EXPENSES AND OTHER CURRENT ASSETS

Prepaid expenses and other current assets consist of the following (in thousands):


	December 31, 2025		December 31, 2024
Insurance	$	929	$	947
Grants receivable	821		1,870
Contract assets	614		332
Vendor advances	416		1,235
IT related	214		259
Other	260		355
Total prepaid expenses and other current assets	$	3,254	$	4,998

5.PROPERTY AND EQUIPMENT, NET

Property and equipment, net consists of the following (in thousands):


	December 31, 2025		December 31, 2024
Machinery and equipment	$	24,413	$	23,306
Leasehold improvements	6,511		6,234
Furniture and fixtures	231		231
Software	764		614
Construction in process	4,303		3,722
Total property and equipment	36,222		34,107
Less: accumulated depreciation	(18,998)		(13,525)
Total property and equipment, net	$	17,224	$	20,582

Depreciation expense related to property and equipment, net was $5.4 million and $4.5 million for the years ended December 31, 2025 and 2024, respectively.

6.INTANGIBLE ASSETS, NET

In September 2023, the Company acquired patent rights valued at $5.0 million under a Patent License Agreement with UOP, an affiliate of Honeywell, a related party. These patent rights were recorded at fair value based on the value of the IP Warrants issued, as defined in Note 13, Common Stock Warrants, and are amortized over an average useful life of 19 years based on the remaining useful lives of the patents acquired. Amortization expense for the years ended December 31, 2025 and 2024 was $0.3 million.

During the fourth quarter of 2025, management concluded it was necessary to reevaluate the usefulness of the assets within the patent portfolio based on the current stage of the Company’s ongoing research and development activities to support the forthcoming Energy Base product offering and related technologies. The assessment resulted in an abandonment charge of $1.7 million, recognized in research and development expense in the consolidated statement of operations and comprehensive loss. When an asset has been abandoned, the estimated useful life of the asset is updated to reflect the cease use date, and the remaining carrying value of the asset is amortized ratably between the commitment date and the cease use date. The abandonment charge was determined based on specific review of the underlying patents.

Intangible assets, net consisted of the following (in thousands):


	December 31, 2025						December 31, 2024
	Cost		Accumulated Amortization		Net Carrying Amount		Cost		Accumulated Amortization		Net Carrying Amount
Patents	$	4,990	$	(2,308)	$	2,682	$	4,990	$	(334)	$	4,656

Estimated future amortization expense of intangible assets as of December 31, 2025 are as follows (in thousands):

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	Intangible Assets
2026	$	267
2027	267
2028	267
2029	267
2030	267
Thereafter	1,347
Total future amortization	$	2,682

7.ACCRUED AND OTHER CURRENT LIABILITIES

Accrued and other current liabilities consist of the following (in thousands):


	December 31, 2025		December 31, 2024
Amounts due to customers	$	6,750	$	—
Payroll and related benefits	1,604		4,351
Contingent liabilities	1,373		702
Professional and consulting fees	782		831
Materials and related purchases	64		2,499
Noncancellable purchase commitments	55		233
Accrued capital purchases	—		320
Other	469		379
Total accrued and other current liabilities	$	11,097	$	9,315

8.ACCRUED PRODUCT WARRANTIES

The following table summarizes product warranty activity (in thousands):


	Year Ended December 31,
	2025		2024
Accrued product warranties - beginning of period	$	3,288	$	2,129
Accruals for warranties issued	376		3,131
Repairs and replacements	(2,135)		(739)
Adjustments to existing accruals	(544)		(1,233)
Accrued product warranties - end of period	$	985	$	3,288

9.LEASES

The Company leases office and manufacturing space in Wilsonville, Oregon under operating leases. In October 2025, the Company exercised renewal options for the leases which were not previously included in the operating lease assets or obligations. These renewals resulted in an increase of $3.8 million to the Company’s right-of-use (“ROU”) assets and lease liabilities and extension of the leases through December of 2027.

The Company determines if an arrangement is a lease at inception and whether the arrangement is classified as an operating or finance lease. At commencement of the lease, the Company records an ROU asset and lease liability in the consolidated balance sheets based on the present value of lease payments over the term of the arrangement. ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. As the Company’s leases do not provide an implicit rate, it uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. The Company determines its incremental borrowing rate based on publicly available data for instruments with similar characteristics, including recently issued debt, as well as other factors. Contract terms may include options to extend or terminate the lease. The Company includes these options in the recognition of its ROU assets and lease liabilities when it is reasonably certain that it will exercise the option. Operating leases reflect lease expense on a straight-line basis, while finance leases will result in the separate presentation of interest expense on the lease liability and amortization expense of the ROU asset.

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ROU assets related to the Company’s operating leases are included in operating lease ROU assets, while the corresponding lease liabilities are included in current and non-current operating lease liabilities on the Company’s consolidated balance sheets. ROU assets related to the Company’s finance leases are included in other non-current assets, while the corresponding lease liabilities are included in accrued and other current liabilities and other non-current liabilities on the Company’s consolidated balance sheets.

The Company does not record leases with a term of 12-months or less in the consolidated balance sheets. Short-term lease costs were immaterial for the year ended December 31, 2025.

Operating lease expense for the years ended December 31, 2025 and 2024 was $1.7 million. Finance lease costs for the years ended December 31, 2025 and 2024 were immaterial.

As of December 31, 2025, future maturities of lease liabilities are as follows (in thousands):


	Operating Leases
2026	2,123
2027	2,186
Thereafter	—
Total minimum lease payments	$	4,309
Less: imputed interest	(465)
Present value of lease liabilities	$	3,844

Weighted-average remaining lease term and discount rate are as follows:


	December 31, 2025		December 31, 2024
Weighted-average remaining lease term (in years)	2.0		1.0
Weighted-average discount rate	11.1	%	9.9	%

10.FINANCING OBLIGATIONS

Sale Leaseback Financing Obligation

On July 10, 2025, the Company entered into a Sale and Leaseback Agreement with UOP, an affiliate of Honeywell, a related party, pursuant to which UOP agreed to purchase the stack assembly line used to build power module stacks for the Company’s products, including the Energy Base, for a purchase price of $10.5 million (comprised of $4.0 million in cash and $6.5 million applied to certain pre-payments from UOP), and to lease such equipment back to the Company (the sale of the property and simultaneous leaseback is referred to as a “sale-leaseback”). The lease term is for 7 years unless terminated early. During the lease term, the monthly lease payment from the Company to UOP is $186 thousand.

The Company assessed the transaction in accordance with ASC 842, Leases, to determine whether it qualified as a sale and leaseback. However, because the underlying lease agreement met the qualifications to be classified as a finance lease, control of the equipment is not considered to be transferred to the buyer/lessor and thus the transaction does not

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qualify as a sale and leaseback under ASC 842. As such, the related financing obligation is accounted for in accordance with ASC 470, Debt.

As of December 31, 2025, the carrying value of the financing obligation to UOP was $10.4 million. Payments are allocated between principal and interest using the effective interest rate method and an effective interest rate of 11%.

Remaining principal payments against the UOP financing obligation imputed using the effective interest rate are as follows (in thousands):


Year Ending December 31,	Annual Payment Obligation
2026	$	1,106
2027	1,236
2028	1,378
2029	1,541
2030	1,721
Thereafter	3,416
Total	$	10,398

Promissory Note

On October 14, 2025, the Company entered into a promissory note agreement with YA II PN, Ltd. (“Yorkville)” for an aggregate principal amount of $40 million and an original issue discount of 8% (the “Promissory Note”). The Promissory Note was structured in two tranches, with the first tranche of $30 million (“Tranche 1”) drawn as of the date of the Promissory Note and the second tranche of $10 million (“Tranche 2”) available to be drawn until December 12, 2025.

In connection with the Promissory Note on October 14, 2025, the Company issued common stock warrants to Yorkville (the “Yorkville Promissory Note Warrants”) which were deemed legally detachable and separately exercisable. See Note 13, Common Stock Warrants. The net proceeds of $27.3 million (after discount and issuance costs) were allocated between the Note and the Yorkville Promissory Note Warrants on the basis of relative fair value.

The Note is payable in 12 periodic payments with a coupon rate of 3%, with a final maturity date of October 14, 2026. Early repayment is permitted. In the event of a default, the interest rate is increased to 18%. The effective interest rate is 291%. Interest expense recognized on the Note during 2025 was $5.2 million, of which $0.1 million was attributable to contractual interest and $5.1 million to amortization of the discount on the Note. As of December 31, 2025, the net carrying amount of the Note and the associated discount were $6.9 million and $2.1 million, respectively. The aggregate amount of principal outstanding of $9.1 million is due within 2026.

The Note was subsequently amended to allow Tranche 2 to be drawn until February 28, 2026. The Company drew Tranche 2 on February 27, 2026, and signed a third amendment to the Promissory Note revising the Tranche 2 repayment schedule to be payable in 12 periodic payments, with a final maturity date of February 27, 2027. The remaining terms and provisions of the Note are unchanged.

11.COMMITMENTS AND CONTINGENCIES

Legal Proceedings

The Company, from time to time, is a party to various claims, legal actions, and complaints arising in the ordinary course of business. The Company is not aware of any material legal proceedings or other claims, legal actions, or complaints through the date of issuance of these financial statements.

Letters of Credit

The Company has a standby letter of credit with Bank of America for $0.6 million as security for the performance and payment of the Company’s obligations under a customer agreement. The letter of credit is in effect until the date on which the warranty period under the agreement expires, which is anticipated to be more than a year from the balance sheet date. As of December 31, 2025, $0.6 million was pledged as collateral for the letter of credit and recorded as restricted cash, non-current. There were no draws against the letter of credit during the year ended December 31, 2025.

The Company has a standby letter of credit with Bank of America for $0.2 million in support of the Company’s customs and duties due on imported materials. The letter of credit is in effect until May 19, 2026. As of December 31,

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2025, $0.1 million was pledged as collateral for the letter of credit and recorded as restricted cash, current. There were draws of $0.1 million against the letter of credit during the year ended December 31, 2025.

Credit Agreement

On November 1, 2024, the Company entered into a Credit Agreement with Export-Import Bank of the United States, as lender, and related agreements related to the financing of two production lines. The Credit Agreement provides for a secured loan facility in an aggregate principal amount of up to $22.7 million, of which $20.0 million is available to be borrowed for equipment financing and the balance will be used to finance an exposure fee and transaction expenses. The loan facility has a maturity date of June 30, 2031. Half of the proceeds of the loan facility may be used on a retroactive basis for the financing of the Company’s existing automated battery assembly line and the remainder may be used for the financing or refinancing of an additional line upon the closing of an equity raise milestone. As of December 31, 2025, the Company had no outstanding borrowings under the Credit Agreement. Any obligations under the Credit Agreement are secured pursuant to a security agreement granting EXIM a first priority security interest in the financed equipment and a securities account containing collateral consisting of cash and cash equivalents in an amount equal to a substantial portion of the disbursements under the Credit Agreement, reportable as restricted cash, that decreases upon the equity raise milestone.

Purchase Commitments

The Company purchases materials from numerous suppliers and has entered into agreements with various contract manufacturers, which include cancellable and noncancellable purchase commitments. As of December 31, 2025 and 2024, total unfulfilled noncancellable purchase commitments were $0.1 million and $0.2 million, respectively. In addition, total unfulfilled cancellable purchase commitments amounted to $0.9 million and $6.0 million as of December 31, 2025, and 2024, respectively.

Joint Development Agreement

In September 2023, the Company entered into a Joint Development Agreement (“JDA”) with UOP, an affiliate of Honeywell, a related party, under which the parties agreed to work collaboratively to engage in certain research and development activities generally related to flow battery technology. Pursuant to the JDA, the Company agreed to reimburse UOP a minimum of $8.0 million for research and development expenses incurred through December 31, 2028. $0.1 million of expenses were incurred under the JDA during the year ended December 31, 2025. No expenses were incurred under the JDA during the year ended December 31, 2024.

12.STOCKHOLDERS’ EQUITY

Baird ATM Program

On March 31, 2025, the Company entered into an at-the-market sales agreement with Robert W. Baird & Co. Incorporated (“Baird”), pursuant to which the Company sold 616,264 shares for total proceeds, net of commission fees, of $0.7 million (the “Baird ATM Offering”). The continuous offering under the ATM prospectus supplement dated March 31, 2025 related to the Baird ATM Offering was terminated on July 11, 2025.

Yorkville Standby Equity Purchase Agreement

On July 9, 2025, the Company entered into a SEPA with YA II PN, LTD. (the “Investor,” “Yorkville”), pursuant to which and subject to the satisfaction of certain conditions, the Investor committed to purchase shares of the Company’s common stock in increments up to an aggregate gross sales price of $25 million during the 36 months following the date of the SEPA. The Company had the right, but not the obligation, to direct the Investor to purchase a specified number of shares of common stock by delivering written notice to the Investor (an “Advance Notice”). The Company paid a commitment fee in an amount equal to $250 thousand by issuing 157,768 shares of common stock.

The shares of common stock purchased pursuant to an Advance Notice were purchased at a price equal to 97% of the lowest daily VWAP of the shares during the three consecutive trading days commencing on the date of the delivery of the Advance Notice. The Company may establish a minimum acceptable price in each Advance Notice below which it will not be obligated to make any sales to the Investor. During the year ended December 31, 2025, the Company issued a total of 6,616,402 shares under the SEPA for total proceeds (net of discount) of $25 million.

Yorkville ATM Program

On November 13, 2025, in connection with an “at the market offering” program, the Company entered into a sales agreement with Yorkville, BMO Capital Markets Corp., Canaccord Genuity LC, Needham & Company, LLC and Stifel, Nicolaus & Company, Incorporated. During the year ended December 31, 2025, the Company sold 2,647,513 shares for total proceeds, net of commission fees, of $6.2 million.

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13.COMMON STOCK WARRANTS

The table below summarizes the common stock warrant activities in the number of shares of common stock issuable upon exercise of the respective warrants during the year ended December 31, 2025:


	December 31, 2024	Issued	Exercised	December 31, 2025
Public Warrants	764,081	—	—	764,081
SMUD Warrant	833	—	—	833
Investment Warrant	708,775	—	—	708,775
IP Warrant	417,997	—	—	417,997
Performance Warrants	51,717	—	—	51,717
Bridge Financing Warrants	—	129,312	—	129,312
Yorkville Promissory Note Warrants	—	1,052,104	—	1,052,104
Total common stock warrants	1,943,403	1,181,416	—	3,124,819

The table below summarizes the common stock warrant activities in the number of shares of common stock issuable upon exercise of the respective warrants during the year ended December 31, 2024:


	December 31, 2023	Issued	Exercised	December 31, 2024
Public Warrants	764,081	—	—	764,081
SMUD Warrant	833	—	—	833
Investment Warrant	708,775	—	—	708,775
IP Warrant	417,997	—	—	417,997
Performance Warrants	51,717	—	—	51,717
Total common stock warrants	1,943,403	—	—	1,943,403

Public Warrants

As part of STWO’s initial public offering, 8,333,287 warrants to purchase common stock (the “Public Warrants”) were sold. Simultaneously with STWO’s initial public offering, STWO issued in a private placement 4,666,667 warrants to purchase common stock (the “Private Warrants”) to STWO’s sponsor. In connection with the Business Combination, STWO’s sponsor agreed to forfeit 583,333 Private Warrants. Of the remaining 4,083,334 Private Warrants, 3,500,000 were immediately vested and 583,334 warrants (the “Earnout Warrants”) were vested upon meeting certain earnout milestone events on November 9, 2021. The Private Warrants, including the Earnout Warrants, automatically converted on a 1:1 basis into Public Warrants upon the transfer of such warrants by the initial holder to a third party during the fourth quarter of 2023.

The Public Warrants are listed on the NYSE under the ticker symbol “GWH.W.” Following the Reverse Stock Split, fifteen Public Warrants entitle the holder thereof to purchase one share of common stock at a price of $172.50 per share, subject to adjustments. The Public Warrants may be exercised only for a whole number of shares of common stock. No fractional shares will be issued upon exercise of the warrants. The Public Warrants expire on October 8, 2026, five years after completion of the Business Combination, or earlier upon redemption or liquidation.

The Company may call the Public Warrants for redemption starting any time, in whole and not in part, at a price of $0.01 per warrant, so long as the Company provides no less than 30 days prior written notice of redemption to each warrant holder, and if, and only if, the reported last sale price of common stock equals or exceeds $270.00 per share for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date the Company sends the notice of redemption to the warrant holders provided there is an effective registration statement covering the shares of common stock issuable upon exercise of the warrants.

The Company may call the Public Warrants for redemption starting any time, in whole and not in part, at a price of $0.10 per warrant, so long as the Company provides no less than 30 days prior written notice of redemption to each warrant holder; provided that holders will be able to exercise their warrants on a cashless basis prior to redemption and receive a number of shares determined based on the redemption date fair market value of the shares, and if, and only if, the reported last sale price of common stock equals or exceeds $150.00 per share for any 20 trading days within a 30-trading day period ending on the third trading day prior to the date the Company sends the notice of redemption to the

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warrant holders provided there is an effective registration statement covering the shares of common stock issuable upon exercise of the warrants.

The Company’s common stock warrants were initially recorded at fair value upon completion of the Business Combination and are adjusted to fair value at each reporting date based on the market price of the Public Warrants, with the change in fair value recorded as a component of other income in the consolidated statements of operations and comprehensive loss. For the years ended December 31, 2025 and 2024, the Company recorded a net decrease to the liabilities for Public Warrants of $0.2 million and $0.1 million, respectively.

SMUD Warrant

On September 16, 2022, the Company entered into a warrant agreement with SMUD, whereby the Company agreed to issue a warrant for up to 33,333 shares of the Company’s common stock at an exercise price of $64.44 per share. The vesting of the shares underlying the warrant is subject to the achievement of certain commercial milestones through December 31, 2030 pursuant to a related commercial agreement. As of December 31, 2025 and 2024, 833 shares underlying the warrant were vested.

Honeywell Warrants

On September 21, 2023, the Company entered a Common Stock and Warrant Purchase Agreement (the “Honeywell Purchase Agreement”) with Honeywell Ventures, an affiliate of Honeywell, a related party. Pursuant to the Honeywell Purchase Agreement, Honeywell invested $27.5 million in the Company and the Company issued 1,099,450 shares of common stock and a warrant to issue up to 708,775 shares of common stock to Honeywell Ventures. Pursuant to the Purchase Agreement and also as further consideration for the licensing by UOP, an affiliate of Honeywell, of certain intellectual property to the Company, the Company issued a warrant to issue up to 417,997 shares of common stock to UOP, which UOP subsequently transferred to Honeywell Ventures. The Investment Warrant has an exercise price of $28.35, and the IP Warrant has an exercise price of $43.50. Each warrant will expire on September 21, 2028.

On September 21, 2023, the Company and UOP also entered into the Supply Agreement, pursuant to which UOP may purchase equipment supplied by the Company. Pursuant to the Supply Agreement, the Company agreed to issue additional warrants to purchase common stock to UOP, consisting of (i) an initial performance warrant to issue up to 51,717 shares of common stock, issued on September 21, 2023 in exchange for a prepayment of equipment by UOP in the amount of $15 million, and (ii) additional performance warrants (not to exceed an aggregate value of $15 million based on target purchase amounts of up to $300 million by 2030) to be issued on an annual basis for the five-year period beginning in 2026, based on UOP’s purchase of additional equipment after execution of the Supply Agreement. The initial Performance Warrant has an exercise price of $21.75 and the additional Performance Warrants will have an exercise price equal to the volume-weighted average price of the Company’s common stock for the last fifteen (15) trading days of the relevant calendar year for which such Performance Warrant is being issued. The initial Performance Warrant will expire on September 21, 2028 and each additional Performance Warrant will have a five-year term from its respective date of issuance.

Bridge Financing Warrants

On July 10, 2025, the Company issued warrants exercisable for an aggregate number of up to 129,312 shares of common stock to certain directors, officers and other employees and the Investor. The warrants were issued at an exercise price of $3.48 per share, payable in cash or, under certain circumstances, pursuant to net exercise. The exercise period commenced on October 13, 2025, the date the shareholders approved the issuance of the shares issuable upon exercise of the Bridge Financing Warrants. The Bridge Financing Warrants will be exercisable until October 13, 2028.

Yorkville Promissory Note Warrants

On October 14, 2025, the Company issued warrants exercisable for an aggregate number up to 1,052,104 shares of common stock (the “Yorkville Promissory Note Warrants”) to Yorkville, in connection with the Promissory Note issued on the same date. The warrants were issued at an exercise price of $9.98 per share, or, under certain circumstances, pursuant to net exercise. The exercise period commenced on October 14, 2025 and will be exercisable until the earlier of (i) October 14, 2030 or (ii) the acquisition of the Company by another entity or the sale, lease or other disposition of all or substantially all of the assets of the Company and its subsidiaries to any party not wholly-owned by the Company (if such events were to occur).

14.STOCK-BASED COMPENSATION

Stock-based compensation expense is allocated on a departmental basis based on the classification of the award holder. The following table presents the amount of stock-based compensation related to stock-based awards issued to

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employees on the Company’s consolidated statements of operations and comprehensive loss during the years ended December 31, 2025 and 2024 (in thousands):


	2025		2024
Cost of revenue	$	2,351	$	2,473
Research and development	858		2,457
Sales and marketing	411		675
General and administrative	1,814		5,970
Total stock-based compensation	$	5,434	$	11,575

2021 Equity Incentive Plan

In October 2021, the Board adopted the ESS Tech, Inc. 2021 Equity Incentive Plan (the “2021 Plan”). The 2021 Plan became effective upon consummation of the Business Combination. Stock awards under the plan may be issued as Incentive Stock Options (“ISO”), Non-statutory Stock Options (“NSO”), Stock Appreciation Rights, and RSUs. Only employees are eligible to receive ISO awards. Employees, directors, and consultants who provide continuous service to the Company are eligible to receive stock awards other than ISOs. The number of shares available for issuance under the 2021 Plan will be increased on the first day of each fiscal year beginning with the 2022 fiscal year and ending with the 2031 fiscal year, in an amount equal to the lesser of (i) 1,017,333 shares, (ii) five percent (5%) of the outstanding shares on the last day of the immediately preceding fiscal year, or (iii) such number of shares determined by the Company no later than the last day of the immediately preceding fiscal year. As of January 1, 2026, the number of shares available for issuance under the 2021 Plan was increased by 1,017,333 shares in accordance with the plan and as approved by the Board. Under the 2021 Plan, the Company has been authorized to issue 3,370,658 shares in total of common stock as of December 31, 2025.

Option prices for incentive stock options are set at the fair market value of the Company’s common stock at the date of grant. The fair market value of RSUs is set at the closing sales price of the Company’s common stock at the date of grant. Employee new hire grants generally cliff vest 1/4th at the end of the first year and then vest 1/16th each quarter over the remaining three years. Grants expire 10 years from the date of grant. All other grants vest quarterly over four years.

As of December 31, 2025, there were 838,603 shares available for future grant under the 2021 Plan.

Stock Options and Restricted Stock Units

Stock option and RSU activity, prices, and values during the years ended December 31, 2025 and 2024 are as follows (in thousands, except for share, per share, and contractual term data):


	Options Outstanding						RSUs
	Number of shares	Weighted average exercise price		Weighted average remaining contractual term (years)	Aggregate intrinsic values ($’000s)		Number of plan shares outstanding	Weighted average grant date fair value per Share
Balances as of December 31, 2024	151,288	$	22.00	5.09	$	84	1,123,890	$	27.72
Options and RSUs granted	50,000	1.72					1,268,189	2.81
Options exercised and RSUs released	(14,035)	5.48					(453,616)	14.46
Options and RSUs forfeited	(58,395)	36.15					(1,152,275)	19.38
Balances as of December 31, 2025	128,858	$	9.63	3.83			786,188	$	7.40
Options vested and exercisable - December 31, 2024	130,876	$	20.64	4.59	$	84
Options vested and exercisable - December 31, 2025	124,742	$	9.24	3.70	$	—

The aggregate intrinsic value is the fair market value on the reporting date less the exercise price for each option. The aggregate intrinsic value of the options exercised was $40 thousand and $45 thousand during the years ended December 31, 2025 and 2024, respectively.

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The fair value of each stock option award is estimated on the date of the grant using the Black-Scholes Merton option-pricing model. For options granted during the year ended December 31, 2025, the weighted average estimated fair value using the Black-Scholes Merton option pricing model was $1.29 per option. No options were granted during the year ended December 31, 2024.

In accordance with ASC 718, the fair value of each option grant during the year ended December 31, 2025 has been estimated as of the date of grant using the following weighted average assumptions:


	2025
Risk-free rate	3.65	%
Expected volatility	100.50	%
Expected term	5.09 years
Expected dividends	—

As of December 31, 2025, there was approximately $2.9 million of unamortized stock-based compensation expense related to unvested stock options and RSUs, which is expected to be recognized over a weighted average period of 2.50 years.

Employee Stock Purchase Plan

In May 2022, the Company commenced its first offering period under the ESS Tech, Inc. Employee Stock Purchase Plan (“ESPP”), which assists employees in acquiring a stock ownership interest in the Company. The ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during specified offering periods. No employee may purchase more than $25,000 worth of stock in any calendar year. The price of shares purchased under the ESPP is equal to 85% of the fair market value of the common stock on the first or last day of the offering period, whichever is lower. Total ESPP expense for the years ended December 31, 2025 and 2024 was $0.1 million and $0.2 million, respectively.

As of December 31, 2025, there were 35,176 shares available for future grant under the 2021 ESPP Plan. The number of shares available for issuance under the ESPP will be increased on the first day of each fiscal year beginning with the 2022 fiscal year and ending with the 2041 fiscal year, in an amount equal to the lesser of (i) 204,000 shares, (ii) one percent (1%) of the outstanding shares on the last day of the immediately preceding fiscal year, or (iii) such number of shares determined by the Company no later than the last day of the immediately preceding fiscal year. As of January 1, 2026, the number of shares available for issuance under the 2021 Plan was increased by 204,000 shares in accordance with the plan and as approved by our compensation committee of our board of directors.

15.FAIR VALUE MEASUREMENTS

The following tables present the Company’s fair value hierarchy for its financial assets measured at fair value on a recurring basis (in thousands):


	December 31, 2025
	Cash Equivalents and Restricted Cash		Short-Term Investments		Total Assets at Fair Value
Level 1:
Money market funds	$	9,191	$	—	$	9,191
U.S. Treasury securities	—		793		793
Total Level 1	9,191		793		9,984
Level 2:

Commercial paper	2,792		6,764		9,556

Total Level 2	2,792		6,764		9,556
Total assets measured at fair value	$	11,983	$	7,557	$	19,540

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	December 31, 2024
	Cash Equivalents and Restricted Cash		Short-Term Investments		Total Assets at Fair Value
Level 1:
Money market funds	$	7,232	$	—	$	7,232
U.S. Treasury securities	—		7,142		7,142
Total Level 1	7,232		7,142		14,374
Level 2:
Certificate of deposit	80		—		80
U.S. agency securities	4,811		7,825		12,636
Commercial paper	—		3,296		3,296
Total Level 2	4,891		11,121		16,012
Total assets measured at fair value	$	12,123	$	18,263	$	30,386

The following tables present the Company’s fair value hierarchy for its financial liabilities measured at fair value on a recurring basis (in thousands):


	December 31, 2025
	Level 1		Level 2		Level 3		Total
Liabilities:
Public common stock warrants	$	573	—		—		$	573
Total liabilities measured at fair value	$	573	$	—	$	—	$	573


	December 31, 2024
	Level 1		Level 2		Level 3		Total
Liabilities:
Public common stock warrants	$	802	—		—		$	802
Total liabilities measured at fair value	$	802	$	—	$	—	$	802

There were no transfers among Level 1, Level 2, or Level 3 categories during the periods presented. The carrying amounts of the Company’s accounts payable and financing obligations approximate their fair values due to their short maturities.

Level 1 Assets: The Company invests in money market funds and U.S. Treasury securities. These assets are valued using observable inputs that reflect quoted prices for securities with identical characteristics.

Level 2 Assets: The Company invests in a certificate of deposit, U.S. agency securities, commercial paper, and corporate debt securities. These assets are valued using observable inputs that reflect quoted prices for securities with similar characteristics and other observable inputs (such as interest rates that are observable at commonly quoted intervals).

Level 1 Liabilities: The Company values its public common stock warrants based on the market price of the warrants.

Level 2 Liabilities: The fair value of the Company’s financing obligations are considered Level 2 as they are based on quoted prices for identical or similar instruments in markets that are not active.

For trading securities held at the reporting date, the net loss and net gain recorded during the years ended December 31, 2025 and 2024, respectively, were immaterial.

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16.INCOME TAXES

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of deferred tax assets and liabilities are as follows (in thousands):


	As of December 31,
	2025		2024
Deferred tax assets:
Net operating losses	$	89,169	$	62,906
Tax credit carryforward	2,075		1,783
Equity compensation	570		827
Capitalized research and development expenses	13,281		16,646
Inventory reserve	1,832		4,247
Deferred revenue	1,508		4,611
Intangible assets	407		(21)
Other	2,931		2,394
Total deferred tax assets	111,773		93,393
Valuation allowance	(110,790)		(93,009)
Deferred tax assets, net of valuation allowance	983		384
Deferred tax liabilities:
Right-of-use assets	(983)		(384)
Net deferred tax	$	—	$	—

ASC 740 requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management assesses that realization is “more likely than not.” Realization of the future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. Because of the Company’s history of operating losses, management believes that recognition of the deferred tax assets arising from the above-mentioned future tax benefits is currently not likely and, accordingly, has provided a valuation allowance for fiscal years 2025 and 2024. The valuation allowance increased by $17.8 million during the year ended December 31, 2025.

As of December 31, 2025, the Company has federal and state net operating loss carryforwards of $334.7 million and $341.9 million, respectively. Federal net operating losses generated prior to 2018 will start to expire in 2032. Federal net operating losses generated after 2017 do not expire. The state net operating losses will begin to expire in 2027. The Company also has federal and state research and development tax credit carryforwards totaling $4.1 million and $28 thousand, respectively. The federal research and development credit carryforwards begin to expire in 2039, unless previously utilized. The state research and development credit carryforwards do not expire.

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The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate as follows (in thousands or percentages, as indicated):


	Year Ended December 31,
	2025
Federal statutory rate	$	(13,322)	21.0	%
State and local income tax, net of federal tax benefit	—		—
Tax credits
R&D tax credits	(585)		0.9
45X production credits	(176)		0.3
Valuation allowance	12,643		(19.9)
Non-taxable or non-deductible items
Stock compensation	1,091		(1.7)
Other	35		(0.1)
Uncertain tax position	293		(0.5)
Other adjustments	21		—
Effective tax rate	$	—	—	%


	Year Ended December 31,
		2024
Federal statutory tax rate		21.0	%
State tax, net of federal tax benefit		1.6
Stock compensation		(2.0)
Non-deductible officer compensation		(0.8)
Permanent differences		(0.1)
Research and development tax credits		0.5
Valuation allowance		(20.2)
Effective tax rate		—	%

The changes in the Company's uncertain tax positions are summarized as follows (in thousands):


Balance as of December 31, 2023	$	1,457
Reductions related to prior year	(68)
Additions related to current year	397
Balance as of December 31, 2024	1,786
Additions related to prior year	4
Additions related to current year	289
Balance as of December 31, 2025	$	2,079

During the years ended December 31, 2025 and 2024, the Company recognized uncertain tax positions of $0.3 million and $0.4 million, respectively, related to a reduction of the research and development credit deferred tax asset.

The Company recognizes interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. The Company had no accrued interest or penalties related to uncertain tax positions as of 2025 and 2024.

The Company files federal and certain state income tax returns, which provide varying statutes of limitations on assessments. However, because of net operating loss carryforwards, substantially all tax years since inception remain open to federal and state tax examination.

Utilization of net operating losses and research and development credit carryforwards may be subject to annual limitations due to ownership changes that have occurred or that could occur in the future, as required by Sections 382 and 383 of the Code, as well as similar state provisions. These ownership changes may limit the amount of net operating losses and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results

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from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of outstanding stock of a company by certain stockholders. Due to the existence of the valuation allowance, limitations created by past ownership changes, if any, will not impact the Company’s effective tax rate.

On July 4, 2025, the One Big Beautiful Bill Act (H.R. 1) (the “OBBB”) was enacted in the U.S. The OBBB includes significant provisions, such as the permanent extension of certain expiring provisions of the Tax Cuts and Jobs Act and immediate expensing of domestic research and development costs, with retroactive application beginning January 1, 2025, as well as changes that impact the availability of ITCs and PTCs. The enactment of the legislation did not have a material impact on our income tax rate during the year ended December 31, 2025 and is not expected to have a material impact on our income tax rate in future years.

17.GOVERNMENT GRANTS

Inflation Reduction Act of 2022 (“IRA”)

On August 16, 2022, President Biden signed the Inflation Reduction Act of 2022 into law. The IRA has significant economic incentives for both energy storage customers and manufacturers for projects placed in service after December 31, 2022. Starting in 2023, there are Production Tax Credits under Internal Revenue Code 45X, that can be claimed on battery components manufactured in the U.S. and sold to U.S. or foreign customers. The tax credits available to manufacturers include a credit for ten percent of the cost incurred to make electrode active materials in addition to credits of $35 per kWh of capacity of battery cells and $10 per kWh of capacity of battery modules. The credits are cumulative, meaning that companies will be able to claim each of the available tax credits based on the battery components produced and sold through 2029, after which the PTC will begin to gradually phase down through 2032.

Since the PTC is a refundable credit (i.e., a credit with a direct-pay option available), the PTC is outside the scope of ASC 740, Income Taxes (“ASC 740”). Therefore, the Company accounts for the PTC under a government grant model. GAAP does not address the accounting for government grants received by a business entity that are outside the scope of ASC 740. The Company’s accounting policy is to analogize to IAS 20, Accounting for Government Grants and Disclosure of Government Assistance, under IFRS Accounting Standards. Under IAS 20, once it is reasonably assured that the entity will comply with the conditions of the grant, the grant money should be recognized on a systematic basis over the periods in which the entity recognizes the related expenses or losses for which the grant money is intended to compensate. The Company recognizes grants once it is probable that both of the following conditions will be met: (1) the Company is eligible to receive the grant and (2) the Company is able to comply with the relevant conditions of the grant.

The PTC is recorded as the applicable items are produced and sold. The Company began earning PTCs in the third quarter of 2023. For the years ended December 31, 2025 and 2024, the Company recognized a PTC benefit of $0.8 million and $1.7 million, respectively, as a reduction of cost of revenue in the consolidated statements of operations and comprehensive loss. As of December 31, 2025 and 2024, grant receivable related to the PTC in the amount of $0.8 million and $1.9 million, respectively, is recorded in prepaid expenses and other current assets on the consolidated balance sheets.

18.REVENUE

Disaggregated Revenue

The following table presents the Company’s revenue, disaggregated by source (in thousands):


	Year Ended December 31,
	2025		2024
Product revenue	$	1,031	$	4,795
Service revenue	108		132
Other revenue	444		1,368
Total revenue	$	1,583	$	6,295

The majority of the Company’s revenue is derived from product sales of energy storage systems. During 2025 other revenue included engineering services related to product site deployment and customer reimbursements for freight and travel. Total revenue in 2025 was partially offset by reductions in revenue related to the wind down of active contracts for legacy business activities in connection with the shift to the Energy Base product offering as discussed within Item

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7, Results of Operations and Note 22, Segment and Other Information. See Note 2, Significant Accounting Policies for further information regarding revenue recognition.

Contract Balances

Contract assets relate to unbilled amounts resulting from contract arrangements in which the related revenue recognition performance obligations have been satisfied, however invoicing to the customer has not yet occurred. Deferred revenue (or contract liabilities) relates to consideration received from customers in advance of the Company satisfying the revenue recognition performance obligations under the related contractual arrangements. Contract balances are reported in a net contract asset or deferred revenue liability position on a contract-by-contract basis at the end of each reporting period. Contract assets are included in prepaid expenses and other current assets and deferred revenue is presented separately on the consolidated balance sheets.

The following table provides information about contract assets and deferred revenue from contracts with customers (in thousands):


	December 31, 2025		December 31, 2024
Contract assets	$	614	$	332
Deferred revenue	5,656		19,637

Contract assets increased by $282 thousand during the year ended December 31, 2025 due to the recognition of revenues for which invoicing had not yet occurred. Deferred revenue decreased by $14.0 million during the year ended December 31, 2025, reflecting recognition of $2.7 million of revenue that was included in the deferred revenue balance at the beginning of the period, deposits reclassified to accrued and other current liabilities in anticipation of returning them to customers of $4.8 million, and deposits applied to the Sale and Leaseback Agreement with UOP of $6.5 million.

Deferred revenue of $0.4 million is expected to be recognized within the next 12 months and non-current deferred revenue of $5.3 million related to the non-refundable deposit discussed in Note 20, Related Parties, is expected to be recognized thereafter as firm orders are received and fulfilled. Additionally, contracted but unsatisfied performance obligations that had not yet been billed to the customer or included in deferred revenue were $1.0 million as of December 31, 2025.

19.DEFINED CONTRIBUTION PLAN

The Company has a 401(k) plan to provide defined contribution retirement benefits for all employees who have completed six months of service. Employees may elect to contribute a portion of their pretax compensation to the 401(k) plan, subject to annual limitations. The Company may make profit-sharing contributions at the discretion of the Board. Employee contributions are always fully vested. For the years ended December 31, 2025 and 2024, the Company contributed $0.6 million and $0.9 million respectively.

20.RELATED PARTY TRANSACTIONS

During the year ended December 31, 2025, the Company recognized revenue of $2.4 million for sales of both completed and in-process energy storage systems and core technology components, reimbursable expenses and extended warranty services provided to related parties. During the year ended December 31, 2024, the Company recognized revenue of $0.6 million for reimbursable expenses, sale and start up of energy storage systems, and extended warranty services provided to related parties.

As of December 31, 2025, the Company had recorded deferred revenue of $194 thousand for sales of extended warranty services and equipment purchases to related parties. As of December 31, 2024, the Company had recorded deferred revenue of $37 thousand for extended warranty services provided to related parties and $63 thousand of outstanding accounts receivable from related parties.

As of December 31, 2025 and 2024, the Company recorded a non-refundable deposit for future equipment purchases by Honeywell of $5.3 million and $14.4 million, respectively, within non-current deferred revenue. As of December 31, 2025 and 2024, the value of the initial Performance Warrant issued to Honeywell was $0.6 million and $0.7 million, respectively, and included within other non-current assets in the consolidated balance sheets. During the year ended December 31, 2025, $0.1 million of the value of the initial Performance Warrant was amortized as an offset to the revenue recognized in the period.

See also Note 6, Intangible Assets, Net, Note 10, Financing Obligations and Note 13, Common Stock Warrants.

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21.NET LOSS PER SHARE

The following table presents the calculation of basic and diluted net loss per share attributable to common stockholders for the years ended December 31, 2025 and 2024 (in thousands, except share and per share data):


	2025		2024
Numerator:
Net loss attributable to common stockholders	$	(63,440)	$	(86,222)
Denominator:
Weighted-average shares outstanding – basic and diluted	14,601,626		11,773,596
Net loss per share – basic and diluted	$	(4.34)	$	(7.32)

Due to the net losses for the years ended December 31, 2025 and 2024, basic and diluted net loss per common share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

The following outstanding balances of equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented:


	2025	2024
Stock options	128,858	151,288
RSUs	786,188	1,123,890
Warrants	3,124,819	1,943,403
Total	4,039,865	3,218,581

22.SEGMENT AND OTHER INFORMATION

The Company has determined that its Chief Executive Officer is its chief operating decision maker (“CODM”). The Company operates as a single business operating segment, which includes all activities related to the design, engineering, and manufacturing of the Company’s long duration energy storage products. Accordingly, the CODM uses gross loss and net loss as reported in the consolidated statements of operations to assess financial performance and inform decisions on how to allocate resources. The financial information provided to the CODM does not contain significant disaggregated expenses outside of what is already disclosed in the consolidated statements of operations. The CODM does not evaluate results using asset or liability information.

Revenue from major customers during the years ended December 31, 2025 and 2024 was as follows (in thousands):


	Years Ended December 31,
	2025		2024
Customer A	$	(1,557)	$	2,804
Customer B	795		2,133
Customer C	2,341		548

The Company recognized a net reduction to revenue associated with Customer A in the current year due to a settlement agreement executed in December 2025 which resulted in a net settlement amount paid by the Company to settle all outstanding obligations with the customer.

Revenue was geographically located as follows (in thousands):


	Years Ended December 31,
	2025		2024
United States	$	3,037	$	3,443
International	(1,454)		2,852
Total revenue	$	1,583	$	6,295

Substantially all of the Company’s long-lived assets and operating lease right-of-use assets were located in the United States as of December 31, 2025 and 2024.

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23.SUBSEQUENT EVENTS

On January 29, 2026, the Company signed a securities purchase agreement with institutional investors pursuant to which the Company agreed to issue and sell in a registered direct offering registered under the Securities Act, an aggregate of 3,471,428 shares of common stock, Pre-Funded Warrants to purchase an aggregate of 5,100,000 shares of common stock at an exercise price of $0.00001 per share, and the 5,100,000 shares of common stock underlying the Pre-Funded Warrants at an offering price of $1.75 per share or $1.74999 per Pre-Funded Warrant, as applicable (the “Registered Direct Offering”). The Registered Direct Offering closed on January 30, 2026.

The net proceeds of the Registered Direct Offering were approximately $14 million, after deducting placement agent fees and expenses and other offering expenses payable by the Company.

As discussed in Note 10, Financing Obligations, on February 27, 2026, the Company drew the second tranche of the Promissory Note with Yorkville and signed a third amendment to the Promissory Note to revise the repayment schedule for a final maturity date of February 27, 2027.

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ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

Not applicable.

ITEM 9A. CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

We have established disclosure controls and procedures that are designed to ensure that the information required to be disclosed by us in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in SEC rules and forms and that such information is accumulated and communicated to management, including our principal executive officer and principal financial officer, as appropriate to allow timely decisions regarding required disclosure.

Under the supervision and with the participation of management, including our principal executive officer and principal financial officer, we conducted an evaluation of the effectiveness of our disclosure controls and procedures as required under Rules 13a-15(e) and 15d-15(e) under the Exchange Act as of the end of the period covered by this Annual Report on Form 10-K. Based on that evaluation, our principal executive officer and principal financial officer have concluded that the Company’s disclosure controls and procedures were effective as of December 31, 2025.

Management’s Report on Internal Controls over Financial Reporting

Management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rule 13a-15(f). Under the supervision and with the participation of management, including our principal executive officer and principal financial officer, we conducted an evaluation of the effectiveness of our internal control over financial reporting based on the framework in “Internal Control — Integrated Framework (2013)” issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this assessment, management concluded that our internal control over financial reporting was effective as of December 31, 2025.

Attestation Report of the Registered Public Accounting Firm

Our independent registered accounting firm is not required to issue an attestation report on our internal control over financial reporting for so long as we qualify as a “smaller reporting company,” as defined under U.S. federal securities laws.

Changes in Internal Control over Financial Reporting

There have been no changes in our internal control over financial reporting during the fiscal year ended December 31, 2025 that materially affected, or which are reasonably likely to materially affect, our internal control over financial reporting.

Inherent Limitations on Effectiveness of Controls

Our system of internal control over financial reporting was designed to provide reasonable assurance regarding the preparation and fair presentation of published financial statements in accordance with generally accepted accounting principles. All internal control systems, no matter how well designed, have inherent limitations. Therefore, even those systems determined to be effective can provide only reasonable assurance and may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

ITEM 9B. OTHER INFORMATION

Securities Trading Plans of Directors and Executive Officers

During the three months ended December 31, 2025, no director or officer, as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” each as defined in Regulation S-K Item 408.

Promissory Note

On February 27, 2026, the Company drew the second tranche of the Promissory Note with Yorkville for $10 million, less the original issue discount of 8% and certain fees and expenses, and signed an amendment to the Promissory Note formalizing the revised repayment schedule. The second tranche will be payable in 12 periodic payments with a coupon rate of 3% and will now have a final maturity date of February 27, 2027. The remaining terms and provisions of the Promissory Note are unchanged.

ITEM 9C. DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS

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Not applicable.

PART III

ITEM 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

The information required by this item is incorporated by reference in our proxy statement relating to our 2026 Annual Meeting of Stockholders. The proxy statement will be filed with the SEC within 120 days of the fiscal year ended December 31, 2025.

ITEM 11. EXECUTIVE COMPENSATION

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

ITEM 14. PRINCIPAL ACCOUNTING FEES AND SERVICES

Our independent registered public accounting firm is KPMG, LLP; Portland, Oregon; Auditor Firm ID: 185.

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PART IV

ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES

(a)Financial Statements and Schedules

The financial statements are set forth under “Part II - Item 8. Financial Statements and Supplementary Data” of this Annual Report on Form 10-K. Financial statement schedules have been omitted since they are either not required, not applicable, or the information is otherwise included.

(b) Exhibit Listing


		Incorporated by Reference
Exhibit	Description	Form	File No.	Exhibit No.	Filing Date	Filed Herewith
2.1#	Merger Agreement, dated as of May 6, 2021, by and among ACON S2 Acquisition Corp., SCharge Merger Sub, Inc. and ESS Tech, Inc.	8-K	001-39525	2.1	May 7, 2021
3.1	Certificate of Incorporation of ESS	8-K	001-39525	3.1	October 15, 2021
3.2	Certificate of Amendment to the Certificate of Incorporation	8-K	001-39525	3.1	May 22, 2023
3.3	Certificate of Amendment to the Certificate of Incorporation	8-K	001-39525	3.1	August 23, 2024
3.4	Amended and Restated Bylaws of ESS	10-Q	001-39525	3.2	November 3, 2022
4.1	Warrant Agreement, dated September 16, 2020, by and between ACON S2 Acquisition Corp. and Continental Stock Transfer & Trust Company	S-4	333-257232	4.1	June 21, 2021
4.2	Description of S ecurities					X
4.3	Assignment, Assumption and Amendment Agreement to the Warrant Agreement, dated October 8, 2021	8-K	001-39525	4.2	October 15, 2021
4.4	Warrant to Purchase Stock, dated September 16, 2022, by and between the Company and Sacramento Municipal Utility District	10-Q	001-39525	4.3	November 3, 2022
4.5	Investment Warrant, dated September 21, 2023	10-Q	001-39525	4.4	November 14, 2023
4.6	IP Warrant, dated September 21, 2023	10-Q	001-39525	4.5	November 14, 2023
4.7	Performance Warrant, dated September 21, 2023	10-Q	001-39525	4.6	November 14, 2023
4.8	Registration Rights Agreement, dated September 21, 2023, by and between the Company and Honeywell ACS Ventures LLC	10-Q	001-39525	4.7	November 14, 2023
4.9	Form of Warrant to Purchase Common Stock dated July 10, 2025	10-Q	001-39525	4.8	August 14, 2025
4.10	Warrant to Purchase Common Stock, dated October 14, 2025	8-K	001-39525	4.1	October 14, 2025
10.1	Form of Registration Rights Agreement	8-K	001-39525	10.4	May 7, 2021
10.2	Form of Subscription Agreement	8-K	001-39525	10.1	May 7, 2021

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10.3

Stockholders’ Agreement, dated as of May 6, 2021, by and among ESS, SBE and BEV

8-K

001-39525

10.5

October 15, 2021

10.4#

Framework Agreement, dated as of March 31, 2021, by and between SBE US Holdings One, Inc. and ESS Tech, Inc.

S-4

333-257232

10.13

June 21, 2021

10.5

Office Lease Agreement, dated July 24, 2017, by and between ESS Tech, Inc. and Parkway Woods Business Park, LLC

S-4

333-257232

10.8

June 21, 2021

10.6†

2021 Equity Incentive Plan and form of award agreements thereunder

10-K

001-39525

10.9

March 2, 2023

10.7†

2021 Employee Stock Purchase Plan

10-K

001-39525

10.10

March 2, 2023

10.8†

Amended and Restated Outside Director Compensation Policy

10-K

001-39525

10.8

March 31, 2025

10.9†

Form of Indemnification Agreement

8-K

001-39525

10.2

October 15, 2021

10.10†

Employment Agreement, dated January 1, 202 6 , by and between ESS Tech, Inc. and Drew Buck ley

10.11†

Separation and Release Agreement, dated February 13, 2025, by and between ESS Tech, Inc. and Eric Dresselhuys

10-K

001-39525

10.11

March 31, 2025

10.12

Common Stock and Warrant Purchase Agreement, dated September 21, 2023, by and between the Company and Honeywell ACS Ventures LLC

10-Q

001-39525

10.1

November 14, 2023

10.13†

Executive Incentive Compensation Plan

10-K

001-39525

10.17

March 13, 2024

10.14#

Credit Agreement, dated November 1, 2024, by and between ESS Tech, Inc. and Export-Import Bank of the United States

10-K

001-39525

10.15

March 31, 2025

10.15†

Kelly Goodman Offer Letter

10-K

001-39525

10.16

March 31, 2025

10.16†

Kate Suhadolnik Offer Letter, dated August 16, 2021

10-Q

001-39525

10.3

November 13, 2025

10.17†

Employment Agreement by and between the Company and Jigish Trivedi, dated August 12, 2025

10-Q

001-39525

10.4

November 13, 2025

10.18

Standby Equity Purchase Agreement, dated July 9, 2025, by and between ESS Tech, Inc. and YA II PN, LTD.

8-K

001-39525

10.1

July 11, 2025

10.19

Sale and Leaseback Agreement, dated July 10, 2025, by and between the Company and UOP LLC

10-Q

001-39525

10.2

August 14, 2025

10.20

Promissory Note, dated October 14, 2025

8-K

001-39525

10.1

October 14, 2025

10.21

Amendment No. 1 to Promissory Note, dated November 12, 2025

10-Q

001-39525

10.6

November 13, 2025

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10.22

Amendment No. 2 to Promissory Note, dated December 4, 2025

8-K

001-39525

10.1

December 5, 2025

10.23

Sales Agreement, dated November 13, 2025, by and between ESS Tech, Inc. and Yorkville Securities, LLC, BMO Capital Markets Corp., Canaccord Genuity LLC, Needham & Company, LLC and Stifel, Nicolaus & Company, Incorporated

8-K

001-39525

1.1

November 13, 2025

10.24

Amendment No. 3 to Promissory Note, dated February 27 , 202 6

19.1

ESS Tech, Inc. Insider Trading Policy

10-K

001-39525

19.1

March 31, 2025

21.1

List of Subsidiaries

23.1

Consent of KPMG LLP, Independent Registered Public Accounting Firm

24.1

Power of Attorney (contained in the signature page to this Annual Report on Form 10-K)

31.1

Certification of Principal Executive Officer pursuant to Rule 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as amended, with respect to the Company’s Annual Report on Form 10-K for the year ended December 31, 2025

31.2

Certification of Principal Financial Officer pursuant to Rule 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as amended, with respect to the Company’s Annual Report on Form 10-K for the year ended December 31, 2025

32.1*

Certification of Principal Executive Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, with respect to the Company’s Annual Report on Form 10-K for the year ended December 31, 2025

32.2*

Certification of Principal Financial Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, with respect to the Company’s Annual Report on Form 10-K for the year ended December 31, 2025

97.1

Compensation Recovery Policy

10-K

001-39525

97.1

March 31, 2025

101.INS

Inline XBRL Instance Document – the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document

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101.SCH

Inline XBRL Taxonomy Extension Schema Document

101.CAL

Inline XBRL Taxonomy Extension Calculation Linkbase Document

101.LAB

Inline XBRL Taxonomy Extension Label Linkbase Document

101.PRE

Inline XBRL Taxonomy Extension Presentation Linkbase Document

104

Cover Page Interactive Data File (formatted as inline XBRL with applicable taxonomy extension information contained in Exhibits 101)

†

Indicates management contract or compensatory plan or arrangement.

Portions of this exhibit have been omitted in accordance with Item 601 of Regulation S-K.

These exhibits are furnished with this Annual Report on Form 10-K and are not deemed filed with the Securities and Exchange Commission and are not incorporated by reference in any filing of ESS Tech, Inc. under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date hereof and irrespective of any general incorporation language contained in such filings.

ITEM 16. FORM 10-K SUMMARY

Not applicable.

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SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Act of 1934, the registrant has duly caused this Annual Report on Form 10-K to be signed on its behalf by the undersigned, thereunto duly authorized.


March 5, 2026
	ESS TECH, INC.

	By:	/s/ Drew Buckley
		Name: Drew Buckley
		Title: Chief Executive Officer
		(Principal Executive Officer)

	By:	/s/ Kate Suhadolnik
		Name: Kate Suhadolnik
		Title: Chief Financial Officer
		(Principal Financial and Accounting Officer)

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POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Drew Buckley and Kate Suhadolnik, jointly and each one of them, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in his or her name, place, and stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10-K, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming that all said attorneys-in-fact and agents, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this Annual Report on Form 10-K has been signed below by the following persons on behalf of the registrant and in the capacities indicated on March 5, 2026.


Signature						Title

/s/ Drew Buckley						Chief Executive Officer
Drew Buckley						(Principal Executive Officer)

/s/ Kate Suhadolnik						Chief Financial Officer
Kate Suhadolnik						(Principal Financial and Accounting Officer)

/s/ Harry Quarls						Chairman of the Board and Director
Harry Quarls

/s/ Michael Niggli						Founding Chairman and Director
Michael Niggli

/s/ Raffi Garabedian						Director
Raffi Garabedian

						Director
Rich Hossfeld

/s/ Sandeep Nijhawan						Director
Sandeep Nijhawan

/s/ Kyle Teamey						Director
Kyle Teamey

/s/ Alexi Wellman						Director
Alexi Wellman

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Date	Price Target	Rating	Analyst
10/10/2025	$3.50	Neutral → Buy	Roth Capital
3/4/2025	$17.00 → $3.00	Buy → Neutral	ROTH MKM
11/14/2024	$14.00 → $9.00	Neutral → Underperform	Robert W. Baird
11/14/2024		Outperform → Perform	Oppenheimer
7/12/2024	$1.50	Buy	ROTH MKM
7/13/2022	$3.75	Hold	Canaccord Genuity
6/29/2022	$3.50	Neutral	Chardan Capital Markets
3/31/2022	$7.00	Hold	Deutsche Bank

SEC Form 10-K filed by ESS Tech Inc.

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