Slide 1: First Quarter 2026 Financial Results Conference Call
Catalyzing a Cleaner Future. Every Day. First Quarter 2026 Financial Results Conference Call Investor Presentation NYSE: GWH May 7, 2026
Slide 2: Disclaimers
Disclaimers No part of this presentation may be reproduced, photocopied, redistributed or passed on, directly or indirectly, to any other person, or published, in whole or in part, for any purpose without the consent of ESS Tech, Inc. (“ESS”). This presentation contains certain “forward-looking stat
Slide 3: Agenda
Agenda First Quarter 2026 Earnings Call ON THE CALL TODAY 1 Company Overview 2 Operational Updates 3 Technology Validation 4 Financial Updates Drew Buckley Kate Suhadolnik 5 Closing Summary Chief Executive Officer Chief Financial Officer 2
Slide 4: Corporate Overview
Corporate Overview ESS is a leading manufacturer of long- duration iron flow energy storage solutions. • “Energy Base”: 10-22 hour long-duration energy storage systems (LDES) for 24/7 renewable power where Li-ion is too costly, unsafe, or inefficient. • Iron flow: stores energy using iron, salt, and
Slide 5: Q1 2026 Highlights and Business Updates
Q1 2026 Highlights and Business Updates ESS is executing on restructuring, commercial progress, and balance sheet improvements ● Iron Flow technology validated at Burbank Water & Power and ● Acquired the intellectual property and assets of VoltStorage Turlock Irrigation District. GmbH, a pioneer in
Slide 6: Real-World Technology Validation
Real-World Technology Validation Independent deployments validate iron flow chemistry underpinning ESS' Energy Base product DEMONSTRATION INFRASTRUCTURE APPA / BURBANK WATER & POWER TURLOCK IRRIGATION DISTRICT 21-Month Utility Demonstration Solar-Over-Canal Commissioning Third-party validation under
Slide 7: Technology Roadmap
Technology Roadmap Building on our solid foundation to deliver Energy Storage assets of the future 2022 – 2025 JUN 2025 FEB 2026 Q3 2026 1H 2027 2H 2027 2+ GWh of Strategic Pivot: R&D Acquired Voltstorage 200 kW System First 800 kW, 10 Hour 5 MW / 50 MWh Transacted Energy at Scale-Up; 70% RTE GmbH C
Slide 8: Financial Results
Financial Results ($ in millions, except per share data) Q1 2026 Q1 2025 Change (%) Q1 2026 Financial Highlights Revenue $0.1 $0.6 (79%) Gross Profit (Loss) $ (7.0) $ (8.1) 14% • Operating expenses declined by 33%, reflecting Operating Expenses $6.7 $10.0 (33%) continued cost discipline and focus on
Slide 9: Reconciliation of GAAP Net Loss to Adjusted EBITDA
Reconciliation of GAAP Net Loss to Adjusted EBITDA ($ in millions) Q1 2026 Q1 2025 Change (%) Net loss $ (15.9) $ (18.0) 12% Q1 2026 Net Loss and Adjusted EBITDA Interest expense (income), net $2.5 $(0.2) 1350% • Net loss improved $2.1 million, or 12% year-over- Stock-based compensation $1.1 $1.2 (1
Slide 10: Cash & Financing
Cash & Financing ($ in millions) 3/31/26 12/31/25 Change Cash & Financing Update Cash¹ & Short-term Investments $21.5 $22.0 $(0.5) • Closed a $15 million registered direct offering at Other Liquid Assets $1.75 per share, priced at a premium to market, for general corporate purposes and working A/R $
Slide 11: Closing Summary
Closing Summary Commercial Momentum & Pipeline • Announced Project New Horizon collaboration with SRP and Google for a 5 MW / 50 MWh pilot deploying Energy Base technology; manufacturing expected in 2026 and delivery targeted for December 2027. • Contract for Large Capacity Energy Storage System to
Slide 12: Questions & Answers
NYSE: GWH Questions & Answers Catalyzing a Cleaner Future. Every Day. COMPANY INVESTOR RELATIONS ESS Tech, Inc. Chris Tyson 26440 SW Parkway Ave, Bldg. 83 Executive Vice President, MZ North America Wilsonville, OR 97070 (949) 491-8235 investors@essinc.com GWH@mzgroup.us essinc.com