CEO Drew Buckley to Discuss Sodium-Ion Strategy, Commercial Traction, the Bridge™ System and Proposed Business Combination

ESS Tech, Inc. ("ESS" or the "Company") (NYSE:GWH), a leading provider of non-lithium energy storage solutions, today announced that ESS's Chief Executive Officer, Drew Buckley, will present at Sidoti's Micro-Cap Virtual Investor Conference on Wednesday, August 19, 2026, where he will discuss ESS's accelerated expansion into U.S.-made sodium-ion energy storage and the Company's recent commercial milestones.

The presentation will highlight recent developments including the Company's letter of intent with Alsym Energy to secure 8.5 GWh of U.S.-made sodium-ion cells and modules, early-stage opportunities approaching $1 billion across data center, critical infrastructure and utility markets, the letter of intent with Juniper Energy for 500 MWh or more of sodium-ion energy storage anchored by a planned 10 MW / 80 MWh utility project in California, and the market rollout of the Bridge™ modular sodium-ion system.

Mr. Buckley will meet with institutional investors and host a presentation on Wednesday, August 19, 2026, at 4:00 p.m., followed by a question-and-answer session. On August 6, 2026, ESS announced the signing of a non-binding letter of intent for a proposed business combination with a private company in the energy sector. The contemplated transaction implies an expected combined enterprise value of approximately $515 million, with the expected transaction value attributable to ESS expected to represent a premium to ESS's market capitalization at the time the definitive agreement is signed. The LOI is non-binding and does not obligate either party to consummate the proposed transaction, and there can be no assurance that definitive agreements will be executed or that the proposed transaction will be completed.

"Sodium-ion has moved from an adjacent opportunity to the center of our strategy, and the demand we are seeing is unlike anything in our company's history," said Drew Buckley. "We look forward to discussing with investors how that demand is converting into commercial traction, how the Bridge™ system positions us to serve data center and utility customers with a domestically sourced, non-lithium solution, and the progress we're making toward definitive agreements on the proposed business combination."

Sidoti’s Micro-Cap Virtual Investor Conference

Presentation: August 19, 2026

Time: 4:00 p.m. Eastern Time

Presentation Registration: Here

Conference Website: Here

Format: Virtual Presentation and 1x1 Meetings

Attendees: Drew Buckley, Chief Executive Officer

ESS will also host virtual one-on-one meetings with investors on Wednesday and Thursday, August 19-20, 2026. To register for the presentation or one-on-ones, visit www.sidoti.com/events.

For more information on Sidoti’s Micro-Cap Virtual Investor Conference, or to schedule a meeting with management, please contact your Sidoti representative. You may also email your request to GWH@mzgroup.us or call Chris Tyson at (949) 491-8235.

About ESS Tech, Inc.

ESS (NYSE:GWH) is the leading provider of non-lithium energy storage solutions. ESS was established in 2011 with a mission to accelerate decarbonization safely and sustainably through longer lasting energy storage. Using easy-to-source materials ESS solutions enable energy security, reliability and resilience. We build flexible storage solutions that allow our customers to meet increasing energy demand without power disruptions and maximize the value potential of excess energy. For more information visit www.essinc.com.

Cautionary Language on Forward-Looking Statements

This communication contains forward-looking statements (including within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, and Section 27A of the Securities Act of 1933, as amended) concerning the Company and other matters that involve substantial risks and uncertainties. These statements may discuss the management team’s goals, beliefs, hopes, intentions and expectations as to future plans, trends, events, results of operations and financial condition, or otherwise, based on current beliefs of the management of the Company, as well as assumptions made by, and information currently available to, the Company’s management. These forward-looking statements can be identified by the use of forward-looking terminology, including the words "anticipate," "believe," "continue," "could," "estimate," "expect," "intends," "may," "might," "plan," "possible," "potential," "predict," "project," "should," "will," "would," or, in each case, their negative or other variations or comparable terminology 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 forward-looking statements are based on ESS’ current expectations and beliefs concerning future developments and their potential effects on ESS. Many factors could cause actual future events to differ materially from the forward-looking statements in this communication. There can be no assurance that the future developments affecting ESS will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond ESS control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements, which include other risks and uncertainties described more fully in Exhibit 99.2 of the Current Report on Form 8-K filed by the Company on June 23, 2026 and the Company’s other filings with the U.S. Securities and Exchange Commission. Except as required by law, ESS is not undertaking any obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise.

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Company

investors@essinc.com

Investor Relations

Chris Tyson

Executive Vice President

MZ Group - MZ North America

Phone: (949) 491-8235

GWH@mzgroup.us

www.mzgroup.us

Media

Brad Dore

VP, Marketing

ESS, Inc.

brad.dore@essinc.com

916-207-7355