A replay of the call will be available via the web at http://investors.essinc.com/. About ESS, Inc. Exhibit 99.1 ESS Tech, Inc. Announces First Quarter 2024 Financial Results Q1 Revenue of $2.7 Million Partnered with Sapele Power to Supply LDES in Africa Completed Testing of First Energy Center for Portland General Electric Ordered Second Power Module Automation Line with 40% Greater Production Capacity Exited Q1 with Cash and Short-Term Investments over $89 million; Expected to Carry ESS Well Into H1'25 WI ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _______ to ________ Commission file number 001-39525 ESS Tech, Inc. (Exact name of registrant as specified in its charter) Delaware 98-1550150 (S ...

Exhibit 99.1 ESS Tech, Inc. Announces Fourth Quarter and Full Year 2023 Financial Results Lowered Q4 Adjusted EBITDA loss by More Than 50% year over year Exited 2023 with Cash and Short-Term Investments over $100 million; Expected to Carry ESS Well Into H1'25 Delivered First Energy Warehouses to Honeywell Energy Warehouse manufacturing cost lowered by 60% in 2023 Target 40% 2024 EW Cost Reduction to Achieve non-GAAP Gross Margin Profitability WILSONVILLE, OREGON – March 13, 2024 – ESS Tech, Inc. ("ESS," "ES ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _______ to ________ Commission file number 001-39525 ESS Tech, Inc. (Exact name of registrant as specified in its charter) (State or oth ...

Disclaimers This Presentation contains statistical data, estimates and forecasts that are based on independent industry publications or other publicly available information. This information involves many assumptions and limitations and you are cautioned not to give undue weight to these estimates. We have not independently verified the accuracy or completeness of the data that has been contained in these industry publications and other publicly available information. Accordingly, neither ESS nor its respec ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _______ to ________ Commission file number 001-39525 ESS Tech, Inc. (Exact name of registrant as specified in its charter) (State or other ju ...

Financial Data and Key Metrics Changes - The company recognized revenue for two energy warehouses in Q1 amounting to approximately $0.4 million, with production completed on nine additional units slated for delivery this year [50][22][57] - Non-GAAP operating expenses for Q1 were reported at $22.8 million, resulting in an adjusted EBITDA of negative $21.4 million [57][62] - The company ended Q1 with $119 million in cash and short-term investments, indicating a strong liquidity position [62] Business Line Data and Key Metrics Changes - The company is transitioning from batch to scale manufacturing, focusing on increasing manufacturing capacity and improving supply chain quality [28][30] - Significant progress has been made in automation, resulting in a labor reduction of 75% and a cycle time improvement of 60% [33][34] Market Data and Key Metrics Changes - There is a notable increase in customer activity driven by significant investment tax credits and production credits available for energy storage solutions [17][18] - The company is experiencing heightened interest from municipal utilities, particularly around resiliency and reliability use cases [72][77] Company Strategy and Development Direction - The company aims to achieve non-GAAP gross margin profitability within the next 12 to 18 months, with a focus on scaling operations and reducing costs [1][28] - Key initiatives for 2023 include scaling manufacturing capacity, improving supply chain quality, optimizing product designs, and reducing commissioning time [28][41] Management's Comments on Operating Environment and Future Outlook - Management expressed optimism about recovering project schedules and strong demand for solutions, despite current project delays [24][50] - The company is preparing to transition out of development accounting in the second half of 2023, which is expected to improve revenue recognition [58][63] Other Important Information - The company has made significant improvements in production efficiency, with labor costs reduced by 60% in the latest design of energy warehouses [59] - The long-term business model is expected to generate higher returns on invested capital over time, with gross margins projected to exceed 30% [65][66] Q&A Session Summary Question: Can you talk about the efficiency seen on deployments? - Management noted that while customer conversations have increased, actual orders have not yet materialized due to hesitations regarding IRS rules [68] Question: Can you expand on the delays at the project and the ability to rework schedules? - Management indicated that the ability to rework schedules depends on customer use cases, with current performance in the 60% efficiency range [70] Question: What is the diversity of opportunities in the total pipeline growth? - Management highlighted increased interest from municipal utilities, particularly due to direct pay from investment tax credits [72][77] Question: Any thoughts on cash burn for the year? - Management expressed confidence in the cash position and the structured plan for the year, indicating a positive outlook for executing plans into 2024 [78]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _______ to ________ Commission file number 001-39525 ESS Tech, Inc. (Exact name of registrant as specified in its charter) Delaware 98-15501 ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _______ to ________ Commission file number 001-39525 (855) 423-9920 Registrant's telephone number, including area code Securities registered purs ...

ESS Tech, Inc. (NYSE:GWH) Q3 2022 Earnings Conference Call November 3, 2022 5:00 PM ET Company Participants Erik Bylin - Investor Relations Eric Dresselhuys - Chief Executive Officer Amir Moftakhar - Chief Financial Officer Conference Call Participants Colin Rusch - Oppenheimer Thomas Boyes - Cowen & Co. Joseph Osha - Guggenheim Partners Chip Moore - EF Hutton Operator Ladies and gentlemen, thank you for standing by. At this time, all participants are in a listen-only mode. Later, we will conduct a question ...