ESS Tech, Inc. (ESS) (NYSE: GWH), a leading manufacturer of iron flow long-duration energy storage (LDES) systems for commercial- and utility-scale applications, today announced that it will hold a conference call on Thursday, May 7, 2026 at 5:00 p.m. EDT to discuss financial results for its first quarter 2026 ended March 31, 2026, and will be providing updates on commercial progress, customer deployments, and anticipated technology milestones. A press release detailing these results will be issued prior to the call.

ESS Tech CEO Drew Buckley and CFO Kate Suhadolnik will host the conference call, followed by a question-and-answer period. The conference call will be accompanied by a presentation, which can be viewed or accessed following the call via the investor relations section of the Company's website here.

To access the call, please use the following information:

Date:	Thursday, May 7, 2026
Time:	5:00 p.m. Eastern Time (2:00 p.m. Pacific Time)
Dial-in:	1-833-461-5787
International:	International Dial-Ins
Meeting ID:	512803249
Webcast:	https://events.q4inc.com/attendee/512803249

The replay can be viewed through the webcast link above and the presentation utilized during the call will be available via the investor relations section of the Company's website here.

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 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 risks and uncertainties described more fully in the section titled "Risk Factors" in the Company's Quarterly Report on Form 10-K filed on March 5, 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.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260423721546/en/

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 Host First Quarter 2026 Financial Results Conference Call on Thursday, May 7, 2026 at 5:00 p.m. Eastern Time