Company Announcements

WILSONVILLE, Ore.--(BUSINESS WIRE)--May 20, 2026-- ESS Tech, Inc. (NYSE: GWH) ("ESS" or the "company"), a leading manufacturer of iron flow, long-duration energy storage (LDES) systems for commercial and utility-scale applications, today announced that management will participate in Clean Energy Group’s Beyond Lithium webinar series.

ESS CEO Drew Buckley will participate in the webinar from 3:00 PM ET to 4:00 PM ET. Buckley will discuss an overview of the company and its iron flow technology, including target applications and related services, market readiness, the path to commercialization, and other key topics.

Clean Energy Group Beyond Lithium webinar series
Date: Wednesday, June 3, 2026
Format: Webinar
Time: 3:00 – 4:00 PM ET
Registration: Click here
Attendee: CEO Drew Buckley

For more information on Clean Energy Group’s Beyond Lithium webinar series, please email your request to ESS@mzgroup.us or call Chris Tyson at (949) 491-8235.

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.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260520295541/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

Source: ESS, Inc.