ESS Tech, Inc. (NYSE:GWH) ("ESS" or the "Company"), a leading manufacturer of long-duration iron flow energy storage systems ("LDES") for commercial and utility-scale applications, today announced that management will attend the upcoming Sidoti Micro-Cap Virtual Conference.

ESS' Chief Executive Officer, Drew Buckley, will participate in one-on-one investor meetings and will also host a presentation from 2:30 PM ET to 3:00 PM ET in Track 1. Mr. Buckley will be discussing recently reported quarterly results, recent validation of the Company's technology, and advancing commercial opportunities.

Sidoti Virtual Micro-Cap Virtual Conference

Date: Wednesday, May 20, 2026

Format: Presentation & Virtual 1x1 Meetings

Presentation: 2:30 – 3:00 PM ET in Track 1

Webcast: Click here

Attendee: Chief Executive Officer Drew Buckley

Conference Website: Click here

For more information on the Sidoti Micro-Cap Virtual Conference, or to schedule a one-on-one meeting with Drew Buckley, please contact your conference representative or you may also email your request to ESS@mzgroup.us or call Chris Tyson at (949) 941-8235.

About ESS Tech, Inc.

ESS (NYSE:GWH) is the leading manufacturer of long-duration iron flow 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 iron, salt, and water, ESS iron flow technology enables 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 forward-looking statements are based on ESS' current expectations and beliefs concerning future developments and their potential effects on ESS. 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 risks and uncertainties described more fully in the section titled "Risk Factors" in the Company's Quarterly Report on Form 10-Q filed on May 7, 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

ESS to Attend Sidoti Micro-Cap Virtual Conference on May 20, 2026