#1RUESSINC Long Duration Energy Storage Systems for a Cleaner Future EW 1561 C ESS ESS MAY 2021 **Subsequent to the date of this presentation, certain estimates and assumptions with relation to ESS' financial projections have changed. See footnote disclosure on Slide 43. CONFIDENTIAL#2Disclaimers ESS" INC This presentation (this "Presentation") was prepared for informational purposes only to assist interested parties in making their own evaluation of the proposed transaction (the "Transaction") between Acon S2 Acquisition Corp. ("ACON", "we", or "our") and ESS Inc. ("ESS"). This Presentation is for discussion purposes only and does not constitute an offer to purchase nor a solicitation of an offer to sell shares of ACON, ESS or any successor entity of the Transaction, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation, or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. This Presentation is not intended to form the basis of any investment decision by the recipient and does not constitute investment, tax or legal advice. No representation, express or implied, is or will be given by ACON, ESS or their respective affiliates and advisors as to the accuracy or completeness of the information contained herein, or any other written or oral information made available in the course of an evaluation of the Transaction. This Presentation provided by ACON and ESS may contain certain forward looking statements, including statements regarding ACON's, ESS's or their management teams' expectations, hopes, beliefs, intentions or strategies regarding the future. The words "anticipate", "believe", "continue", "could", "estimate", "expect", "intends", "may", "might", "plan", "possible", "potential", "predict", "project", "should", "would" and similar expressions 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 are based on ACON's and ESS's current expectations and beliefs concerning future developments and their potential effects on ACON, ESS or any successor entity of the Transaction. Many factors: could cause actual future events to differ materially from the forward-looking statements in this presentation, including but not limited to: (i) the risk that the Transaction may not be completed in a timely manner or at all, which may adversely affect the price of ACON's securities, (ii) the failure to satisfy the conditions to the consummation of the Transaction, (iii) the occurrence of any event, change or other circumstance that could give rise to the termination of the Agreement and Plan of Merger, (iv) the effect of the announcement or pendency of the Transaction on ESS's business relationships, operating results and business generally, (v) risks that the Transaction disrupts current plans and operations of ESS, (vi) changes in the competitive and highly regulated industries in which ESS plans to operate, variations in operating performance across competitors, changes in laws and regulations affecting ESS's business and changes in the combined capital structure, (vii) the ability to implement business plans, forecasts and other expectations after the completion of the Transaction, and identify and realize additional opportunities, and (viii) such other risks and uncertainties included in the separate summary risk factors. There can be no assurance that the future developments affecting ACON, ESS or any successor entity of the Transaction will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond ACON's or ESS's 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. Except as required by law, ACON and ESS are not undertaking any obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise. All rights to the trademarks, copyrights, logos and other intellectual property listed herein belong to their respective owners and ACON's or ESS's use thereof does not imply an affiliation with, or endorsement by the owners of such trademarks, copyrights, logos and other intellectual property. Solely for convenience, trademarks and trade names referred to in this Presentation may appear with the Ⓡor TM symbols, but such references are not intended to indicate, in any way, that such names and logos are trademarks or registered trademarks of ACON. Use of Projections. The financial and operating forecasts and projections contained herein represent certain estimates of ESS as of the date thereof. Neither ACON's nor ESS's independent public accountants have examined, reviewed or compiled the forecasts or projections and, accordingly, neither expresses an opinion or other form of assurance with respect thereto. Furthermore none of ACON, ESS nor their respective management teams can give any assurance that the forecasts or projections contained herein accurately represents ESS's future operations or financial conditions. Such information is subject to a wide variety of significant business, economic and competitive risks and uncertainties, including but not limited to those set forth in the second paragraph above that could cause actual results to differ materially from those contained in the prospective financial information. Accordingly, there can be no assurance that the prospective results are indicative of the future performance of ACON or ESS or that actual results will not differ materially from those presented in the prospective financial information. Some of the assumptions upon which the projections are based inevitably will not materialize and unanticipated events may occur that could affect results. Therefore, actual results achieved during the periods covered by the projections may vary and may vary materially from the projected results. Inclusion of the prospective financial information in this presentation should not be regarded as a representation by any person that the results contained in the prospective financial information are indicative of future results or will be achieved. 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, none of ACON, ESS nor their respective affiliates and advisors makes any representations as to the accuracy or completeness of these data. This Presentation contains references to ESS's achievements compared to other companies. All of such references are based on the belief of ESS's management based on publicly available information known to ESS's management. Non-GAAP Financial Measures. The financial information and data contained in this Presentation is unaudited and does not conform to Regulation S-X promulgated under the Securities Act of 1933, as amended. This Presentation also includes non-GAAP financial measures, including gross margin and Adjusted EBITDA. ACON and ESS believe that these non-GAAP measures of financial results provide useful information to management and investors regarding certain financial and business trends relating to ESS's financial condition and results of operations. ESS's management uses certain of these non-GAAP measures to compare ESS's performance to that of prior periods for trend analyses and for budgeting and planning purposes. Not all of the information necessary for a quantitative reconciliation of these forward-looking non-GAAP financial measures to the most directly comparable GAAP financial measures is available without unreasonable efforts at this time. Specifically, ESS does not provide such quantitative reconciliation due to the inherent difficulty in forecasting and quantifying certain amounts that are necessary for such reconciliations. This Presentation relates to a proposed transaction between ESS and ACON. This Presentation does not constitute an offer to sell or exchange, or the solicitation of an offer to buy or exchange, any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, sale or exchange would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. ACON and ESS intend to file a registration statement on Form S-4 with the U.S. Securities and Exchange Commission (the "SEC"), which will include a document that serves as a joint prospectus and proxy statement, referred to as a proxy statement/prospectus. A proxy statement/prospectus will be sent to all ESS and ACON shareholders. ESS and ACON will also file other documents regarding the proposed transaction with the SEC. Before making any voting decision, investors and security holders of ESS and ACON are urged to read the registration statement, the proxy statement/prospectus and all other relevant documents filed or that will be filed with the SEC in connection with the proposed transaction as they become available because they will contain important information about the proposed transaction. Investors and security holders will be able to obtain free copies of the registration statement, the proxy statement/prospectus and all other relevant documents filed or that will be filed with the SEC by ESS and ACON through the website maintained by the SEC at www.sec.gov. Participants in the Solicitation. ESS, ACON and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from ACON's shareholders in connection with the proposed transaction. A list of the names of such directors, executive officers, other members of management, and employees, and information regarding their interests in the business combination will be contained in ACON's filings with the SEC, and such information and names of ESS's directors and executive officers will also be in the Registration Statement on Form S-4 to be filed with the SEC by ACON, which will include the proxy statement of ACON. Additional information regarding the interests of such potential participants in the solicitation process will also be included in the registration statement (and will be included in the definitive proxy statement/prospectus) and other relevant documents when they are filed with the SEC. CONFIDENTIAL|#3RESSING Game Changing Technology The Power Grid of the Future - Feasible Today STABLE. SECURE. CLEAN. CONFIDENTIAL |#4Transaction Overview Category Catalyst in Long Duration Energy Storage Solutions ESS ■ Founded in 2011 to enable the stable, decentralized and decarbonized power grid of the future Offering Size ▪ACON S2 (NASDAQ: STWO): a special purpose acquisition company ▪$250 million cash in trust Leadership ESS INC Valuation - PIPE size of $250 million $1,072 million pro forma enterprise value Capital Structure Investors ESS' Key and Partners ■ Attractive value, high-growth, genuinely sustainable business ■ ESS shareholders rolling 100% of equity $465 million net proceeds (assuming no redemptions) Fully funded to projected cash flow profitability O-BASF evergy ventures Sad Rep Breakthrough Energy VENTURES SB Energy ptt ( PANGAEA VENTURES LTD. Note For additional information, please refer to the Detailed Transaction Overview on p. 36 of this presentation. Craig Evans President & Founder Eric Dresselhuys CEO (March 2021) Julia Song CTO & Founder Adam Kriger CEO & Director ACONS2 RUESSINC Amir Moftakhar CFO John Roush CFO & Chairman Alan Greenshields ACON Advisor CONFIDENTIAL | 3#5We Must Reimagine the Grid Aging Infrastructure Severe Weather Events Rising Renewables Penetration Growing Energy Demand RESSING CONFIDENTIAL | 4#6Energy Transition is Building Momentum Stakeholders are aligned to accelerate the energy transition towards a more sustainable future Consumer Preferences Corporate Commitments A Regulatory Energy Transition Investor Mandates Capital Markets RUESSINC "Anybody who has the breakthrough on battery storage is going to have the key to the future" John Kerry (U.S. Special Presidential Envoy for Climate) "It's a question of when, not if, the global economy will shift way from fossil fuels" Bloomberg "Renewables should supply 90% of all energy needs...fossil fuel usage would fall by 75%" IRENA "Transmission and energy storage certainly have critical roles to play, with broader interconnection and high voltage transmission corridors to build regional resilience" Nuclear Innovation Alliance CONFIDENTIAL | 5#7ESS is a Game Changer in Long Duration Energy Storage RESS INC Stabilizes the Grid Enables up to 100% Renewable Penetration Allows Proliferation of Microgrids CONFIDENTIAL| 6#8ESS: A Category Defining Investment Opportunity 1 Large and Fast-Growing TAM: ~$56bn by 2027 growing at a 33% CAGR¹ 2 Simple Yet Revolutionary Technology: Iron, salt and water; strong patent portfolio ESS INC 3 Compelling Value Proposition: Highest performance, lowest cost² and most sustainable 4 Low Risk Expansion Plan: Field proven³ technology with low-cost manufacturing build out 5 INC RESSI $7bn of Identified Opportunities: $300m+ SoftBank Energy framework agreement through 2026 1 234 6 Premier Management Team: Founders and inventors supported by an experienced team Guidehouse Insights, 'Market Data: Utility-Scale Energy Storage Market Update', 3Q 2020; Guidehouse Insights, 'Market Data: Energy Storage for Microgrids and Remote Power Systems', 2Q 2020; and Navigant Research, 'Distributed Energy Storage Overview', 4Q 2019. Management Estimates of levelized cost of storage (LCOS) among long duration Storage Systems. Based on our Generation I products, which are no longer deployed. Our $7.0 billion pipeline of visible potential opportunities for 2021 through 2027 was determined based on named projects with customers ESS has spoken to and signed non-disclosure agreements with in order to discuss the projects. We have assumed project volumes of eight, 10 and 12-hour energy storage durations and pricing based on our current 2021 pricing for our products. Actual pricing will be project specific. Our pipeline includes both Energy Warehouse and Energy Center projects and global opportunities. There is no assurance that we will enter into all of the markets that we have projected in our pipeline. CONFIDENTIAL| 7#9Market Opportunity EC RESSING RESS INC CONFIDENTIAL 8#10What Is Long Duration Storage? Shift Supply to Meet Demand from 4 - 12 Hours Low Cost to Enable Replacement of Alternatives (Peaker Plants) Reliable (Grid Stability) ESS" INC CONFIDENTIAL | 9#11ESS Transforms the Value Proposition for Long Duration Storage RESS" INC What Customers Demand Up to 12 hours Longer Duration ESSINC Flexibility allows multiple revenue streams $ Low Cost ■ Lower LCOS than other technologies in the market ■ Incremental cost of storage <$20/kWh ་ Power On Demand + Safety and Reliability Sustainability How ESS Transforms the Grid ■ Can replace coal and natural gas with solar and wind power ■ Greater resiliency to unexpected events Step function improvement in economics of storage ■ Enables multiple use cases ■ <1 second response time >20,000 cycle life - $0 marginal cost per cycle Non-flammable, non-toxic, no explosion risk ■ Munich RE insures technology risk Improved grid resiliency and flexibility ■ Can deploy in a wide range of geographies and climates ■ Customers can be confident in a long-term solution Easily sourced materials; recyclable components "Plug and play" with 25-year operating life Environmentally sustainable ■ Accelerates clean energy transition CONFIDENTIAL | 10#1212 Stabilize the Grid and Accelerate Renewables GW RESSI INC US Renewable Energy Penetration (2015-2050)1 65% 57% 47% 40% 36% 31% 23% 15% 2015 2020 2025 2030 2035 2040 2045 2050 California Duck Curve and % Renewable Penetration1,2 25 15 5 -2013 (10%) -2019 (27%) Impact of renewables on the grid 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Renewable intermittency creates a massive problem for the grid, particularly >25% penetration Carbon-free is the goal Intermittency and curtailment are barriers ■4-hour storage does not efficiently bridge. the duck curve Longer duration solutions enable peaker plant replacements Hour of day BloombergNEF. IEA, "The California Duck Curve", December 2019. % figures represent solar and wind power penetration in each year. CONFIDENTIAL| 11#131 Fortify the Grid for Climate Change TEXAS 407 Climate change will result in more unpredictable weather events including extreme temperatures, hurricanes and wildfires1 Texas Freeze ESS batteries operate efficiently in extreme hot and cold weather and still maintain grid stability Texas was seconds away from complete grid failure, which could have taken months to bring back online California Fires ESS batteries are safe for people and the environment: non-flammable and non-toxic Microgrids ESS enables independence Diffenbaugh, N., 'Verification of extreme event attribution: Using out-of-sample observations to assess changes in probabilities of unprecedented events.' Science Advances, Vol. 6, No. 12. 18 March 2020. ESS CONFIDENTIAL | 12 INC#14Strong and Growing Demand for Energy Storage Cumulative Additions to Global Storage Capacity (GWh) Global Total Addressable Market ($bn) RESSINE Front of the meter Behind of the meter Front of the meter 534 +43% CAGR Behind of the meter +33% $56 CAGR 397 301 +44% CAGR $46 $39 $28 +32% CAGR 287 226 $33 $22 $27 $19 199 $22 168 $18 $17 $15 130 +34% 121 $14 233 +42% $28 CAGR 79 83 33 171 CAGR $8 $12 $24 $20 39 $15 11 52 119 $4 $12 6 26 77 $8 47 $4 $5 13 27 2020 2021 2022 2023 2024 2025 2026 2027 2020 2021 2022 2023 2024 2025 2026 2027 ESS has observed even greater demand from customers than these current analyst estimates Source Guidehouse Insights, 'Market Data: Utility-Scale Energy Storage Market Update', 3Q 2020; Guidehouse Insights, 'Market Data: Energy Storage for Microgrids and Remote Power Systems', 2Q 2020; and Navigant Research, 'Distributed Energy Storage Overview', 4Q 2019. CONFIDENTIAL | 13#15ESS Wins on Performance INC RESSI Operational Flexibility RESSIN IC Li-Ion 4-12 hrs 16+ hrs <4 hrs Unlimited cycles, no capacity loss Longer Asset Life ESS Li-Ion 6,000 cycles¹ Superior Ambient ESSIN Operating Temperature Li-Ion -10°C-60°C 20-25°C Safety ESS Li-Ion INC Non-flammable No Explosion Risk Compelling Performance Can cycle when needed with no impact to asset life Operates at peak efficiency independent of outside environment ✔ No heating/cooling systems needed ✓ Safe for deployment to urban areas or harsh and pristine environments 1 Li-Ion cyclability from BYD energy storage system factsheets. CONFIDENTIAL | 14#1612 ESS Wins on Cost Capital Cost ($/kWh) RESS INC Illustrative Cost Comparison Versus Li-Ion Competitive with Li-Ion at 4 hours; ESS wins thereafter ESSNE Li-Ion How ESS' Technology Delivers Superior Economics¹ 4 hours No scaling $200/kWh Marginal cost of $20/kWh 12 hours $200/kWh Li-Ion ESS 'INC Li-Ion $200/kWh $80/kWh LCOS at 4 hours vs. 12 hours² $0.07 $0.08 RESS INC $0.02 $0.05 4 12 16 12 hours 4 hours Duration (hours) Figures shown are illustrative. Superior economics based on Levelized Cost of Storage (LCOS). LcOS = Σ. CapEx +Σ. Installation +Σ. Disposal +Σ.0&M Σ. Annual Usable KWh CONFIDENTIAL | 15#17ESS Wins on Sustainability Sustainability Focus Areas Responsibly Sourced Materials RESS INC Raw ingredients of iron, salt and water are earth-abundant Global Warming Potential (GWP) 67% lower CO2 emissions than Li-Ion¹ Recyclability Contains no toxic materials and requires no special permits for disposal² GHG impact is dependent on specific Li-Ion chemistry. He, H. et al. "Flow Battery Production: Materials Selection and Environmental Impact." Journal of Cleaner Production. Vol. 269. 1 October 2020. Noguera, E., Comparative LCA of stand-alone power systems applied to remote cell towers, 2014. Note 1 2 No hazardous materials compliance plan required. RESS" INC CONFIDENTIAL | 16#18ESS is a Category Defining Technology for Long Duration Storage RUESSINC ESS INC Li-Ion Li Metal Vanadium, Zinc Bromine Sodium Sulfur Compressed Air Pumped Hydro Low cost at 4 - 12 hours Field proven¹ Earth abundant materials Unlimited cycling Zero capacity fade Wide operational temperature range Environmentally sustainable No fire/ explosion risk Note 1 20 R Internally developed table based on company data and publicly available information. Based on our Generation I products, which are no longer deployed. О О О О О Re 0000000 О О OO о О О CONFIDENTIAL | 17#19ESS Technology is Proven and Insured Munich RE Investment-Grade Warranty 10-year extended warranty covering battery modules Aon One Beacon Surety and Corporate Bonding Growing project surety capacity Investment-Grade Project Insurance Warranty continuity insurance provides additional surety to customers and financiers EXIM RESSI INC 'The ability to ensure battery performance is a key piece of the puzzle in decarbonizing our energy sector." -Peter Röder, Member of the Board of Management, Munich RE US Export-Import Bank Qualified Pre-qualified financing available for overseas buyers CONFIDENTIAL | 18#20ESS is Winning in the Market Today Use Case Customer in California Microgrid solutions required to mitigate Public Safety Power Shutdown impacts ■Li-Ion solutions disqualified due to wildfire risk Why ESS Won Energy Warehouse™ deployed Best-in-class safety record Participates in CAISO Provides local utility grid support during non-PSPS months Use Case Customer in Patagonia ■ Remote grid served by RoR hydro + diesel gensets Storage systems required to minimize genset usage Why ESS Won 300 kW/2 MWh Energy Warehouse™ deployed ■ Client abandoned Li-ion RfP after recognizing ESS' 3x greater peaker replacement capability $3.1M incremental savings over Li-Ion Avoids 12 years of diesel genset emissions INC ESS EW 1000 CONFIDENTIAL RESSINC#21Technology Overview RESS INC CONFIDENTIAL| 20#22Technological Breakthrough, Field Proven and Shipping Now Iron Flow first conceived in 1970s But "dirty" electrolyte caused rapid degradation Technological breakthrough - Proton Pump eliminates power fade and limits on cycle life Technological Success Proven Over Time 2017 2020 Demonstrated 10,000+ operating cycles in the lab Gen I EW product line launched Installed S200 automated assembly line 2011 Company formed Developed lab scale battery 2014 2012 2015 Awarded ARPA-e grant for development of Iron based battery First commercial deployment 1 Based on our Generation I products, which are no longer deployed. Energy Center™ product line launched 2019 S200 commercial battery module launched 55 Field proven¹; S200 shipping now RUESSINC R&D roadmap for additional breakthroughs to extend technology advantage Innovative Technology I Proton I Pump (+) ELECTRODE: High surface area carbon electrode (-) ELECTRODE: Carbon composite substrate with polypropene spacer SEPARATOR: Porous polyethylene separator ELECTROLYTE: Ferrous Chloride in aqueous solution CONFIDENTIAL| 21#23Robust Intellectual Property Portfolio ESS Critical Technology Proton Pump Electrolyte J- Power Module Current Collector = Patent protected 1 As of March 25, 2021. Pressure Plate DO (-) Electrode Conductive Separator (+) Electrode ESS IP Portfolio 125+ Patents Granted and in Pipeline Pending Applications RUESSINC Porous Separator Undisclosed Number of Trade Secrets and Identified Patents World-leading Iron Flow expertise, and roadmap to additional breakthroughs and advantages ~57% Employees Have an Engineering Background¹ CONFIDENTIAL | 22#24Business Overview EC RESSING RESS INC CONFIDENTIAL | 23#25Strong Team Positioned to Grow the Business Management Team CRAIG EVANS President & Founder United Technologies ClearEdge rower HUGH MCDERMOTT Senior Vice President Business Development Silver Spring NETWORKS better place ERIC DRESSELHUYS Chief Executive Officer (March 2021) SEW Silver Spring SMART ENERGY WATER MATT BERKEBILE Vice President Operations AMIR MOFTAKHAR Chief Financial Officer SDGE A Sempra Energy utazy" COX. DR. JULIA SONG CTO & Founder Milliken ClearEdge Powe BRIAN LISIECKI Vice President Business Systems Campbells GODIVA Board of Directors C RANDY LEWIS Vice President Quality PCC FLIR GE Energy MHPS MICHAEL NIGGLI Chairman, San Diego Gas & Electric Co & Entergy SDGE A Sempra Energy unity" NVEnergy CRAIG EVANS President & Founder United ClearEdge rower Technologies RAFFI GARABEDIAN Board Member, First Solar TOUCHDOWN TECHNOLOGIES First Solar. VERIFY company KYLE TEAMEY Board Member, Breakthrough Energy Ventures Breakthrough Energy VENTURES ERIC DRESSELHUYS Chief Executive Officer (March 2021) Silver Spring NETWORKS SEW SMART ENERGY WATER DARYL WILSON Board Member, Hydrogenics, ATS Automation. AT HYDROGENICS TOYOTA RICH HOSSFELD Board Member, SoftBank Energy =SB Energy First Solar SHIRLEY SPEAKMAN Board Member, Cycle Capital CYCLE CAPITAL MANAGEMENT RESS" INC CONFIDENTIAL | 24#26One Technology - Two Products of Different Scale ESSIN EW 50k 400kWh TM EC ESS INC Energy Warehouse at Jean Airport Energy Warehouse" Behind the meter solution ▪ 50kW - 90kW configurable range First commercial deployment in 2015 ■ Generation II launched in 2020 Containerized design for turnkey delivery ■ Fast to build and commission ☐ Energy Center™ Front of the meter solution ■Customizable configuration range ■ Customer trials starting in 2021 ◉ "Battery in a Building" platform ■Modular design for utility-class RESS INC CONFIDENTIAL| 25#27Validated by a Blue-Chip Customer Base Utilities IPPS/Developers EW EC EW EC RESSINC Commercial & Industrial EW EC ■ Peaker replacements Demand Drivers ■ T&D upgrade deferrals ■ Wildfire resiliency ■ Peaker replacements Energy cost savings ■ Resource adequacy & grid reliability " Operational resiliency 24/7 power supply Distributed energy services products Microgrids Engie Select Customers / Use Cases San Diego Gas & Electric SB Energy SoftBank Group SWORD STONE ■RE integration Carbon footprint reduction/ESG goals Applied Medical Pacto Energia ČEZ Group Duke Energy Grupo ConEdison Energy Starwood Enel Honeywell Idimax Select Pipeline Naturgy Marathon transelec SAESA Energy SUNRISE ENERGY PacifiCorp CONFIDENTIAL | 26 Note "EW" refers to Energy Warehouse™, "EC" refers to Energy Center™#28Strategy to Scale Globally ESS' ability to grow is supported by ✓ Relationships in Europe and Asia-Pacific ✓ Automated manufacturing process Supply chain of readily sourced components and raw materials ~10,000 ~5,000 ~150 2021 ~2,000 RESSI INC Manufacturing Capacity (MWh) ~16,000 150,000 sq. ft. manufacturing facility in Oregon Robotic automation cell designed and built by ESS 2022 Strategic investments in supply chain to grow capacity Roll out of redesigned automation cells (2x efficiency) 2023 Australia manufacturing go- live for EW with LOI on Brisbane facility 2024 Australia manufacturing go-live for EC and Power Module Europe manufacturing go-live for EC and EW 2025 Europe Power Module manufacturing go-live Vertically integrate power module comportments CONFIDENTIAL | 27#2997% Less Capital Required - Ready to Scale Globally Simple, Low-cost Production in the USA $in millions/GWh of Battery Module Production Capacity ~$140 Simple, automated ESS manufacturing line Li-Ion competitor ~$4 ESSIN Source Lux Research. RESS INC Expensive, complex Li-Ion battery manufacturing line CONFIDENTIAL | 28#30Capital Investment Will Enable Rapid Expansion Net Cash for Growth ~$493m¹ EC Increase Manufacturing Capacity Fully funds capital plan to increase capacity from >250MWh in 2021 to 16GWh by 2025 TM Launch Energy Center™ Deploy product that is optimized for the fast-growing utility-scale storage segment Expand Sales Footprint Hire new sales team members and expand production footprint into Europe and Australia Strengthen Balance Sheet Supports credit requirements to convert large projects in pipeline RESS" INC Further Extend Technology Advantage Higher performance electrolyte to enable an 85% reduction in cost per megawatt hour by 2025 PF 12/31/2020 net cash assumes funding of $27.5m of C-2 raise, of which $16m has yet to be funded; amount is expected to be funded prior to transaction close. Net cash also includes $1.5m of restricted cash. For additional information, please refer to the Detailed Transaction Overview on p. 36 of this presentation. CONFIDENTIAL| 29#31Financial Forecast RESS INC CONFIDENTIAL | 30#32High Quality Pipeline Projected Pipeline for Energy Center™ and Energy Warehouse™ Global Identified Opportunities Negotiating 28% Qualifying 40% Booked 100% Awarded 66% Negotiating 40% Booked Awarded 6% 20% 2021E 2022E 2023E Energy Center™ Opportunities Energy Warehouse™ Opportunities $2 Million $37 Million $300 Million $7+ Billion Pipeline for Continued Growth in Outer Years RESSINC CONFIDENTIAL | 31#33ESS' Robust Revenue Growth Projected Revenue by Product Offering ($in millions) EC EW EF Services $1,645 $2,572 $3,562 $803 $300 $2 $37 2021E 2022E 2023E 2024E 2025E 2026E 2027E Market Share % 0% 0% 1% 2% 4% 6% Note Total addressable market value for the microgrid, distributed energy and utility industries from Guidehouse Insights. RESSI INC ☐ Growth accelerates as Energy Center deployments start in 2023 Forecast driven by identified pipeline of near-term opportunities ESS expansion into Australia (2023) and Europe (2024) supports continued growth Energy Franchise lease and Services revenue streams become bigger contributors as ESS expands CONFIDENTIAL | 32