#1Eos Energy Enterprises Q3 2023 Financial Results November 7, 2023 Eos. Positively ingenious. eos. TM#2Disclaimer 2 Forward-Looking Statements This presentation includes "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. The words "anticipate," "believe," "continue," "could," "estimate," "expect," "intends," "may," "might," "plan," "possible," "potential," "predict," "project," "should," "would" and similar expressions, as they relate to us, are intended to identify forward-looking statements. These statements appear in a number of places in this presentation and include statements regarding the intent, belief or current expectations of Eos Energy Enterprises, Inc. ("Eos"), including but not limited to statements regarding current expectations with respect to future results and outlook for the fiscal year ended December 31, 2023, statements regarding the tax credits available to our customers or to Eos pursuant to the Inflation Reduction Act of 2022, statements regarding our ability to secure final approval of a loan from the Department of Energy LPO, or our anticipated use of proceeds from any loan facility provided by the US Department of Energy, statements that refer to 2023 outlook, projections, forecasts or other characterizations of future events or circumstances, including any underlying assumptions. Forward-looking statements are based on our management's beliefs, as well as assumptions made by, and information currently available to them. Because such statements are based on expectations as to future financial and operating results and are not statements of fact, actual results may differ materially from those projected. Factors which may cause actual results to differ materially from current expectations include, but are not limited to: changes adversely affecting the business in which we are engaged; our ability to forecast trends accurately; our ability to generate cash, service indebtedness and incur additional indebtedness; our ability to raise financing in the future; our customer's ability to secure project financing; the amount of final tax credits available to our customers or to Eos Energy Enterprises, Inc. pursuant to the Inflation Reduction Act; uncertainties around our ability to secure final approval of a loan from the Department of Energy, the Loan Programs Office in a timely manner or at all, or the timing of funding and the final size of any loan if approved; the possibility of a government shutdown while we negotiate loan financing documents with the U.S. Department of Energy Loan Programs Office or while we await notice of a decision regarding the issuance of a loan or an advance from the Department Energy Loan Programs Office; our ability to develop efficient manufacturing processes to scale and to forecast related costs and efficiencies accurately; fluctuations in our revenue and operating results; competition from existing or new competitors; the failure to convert firm order backlog and pipeline to revenue; risks associated with security breaches in our information technology systems; risks related to legal proceedings or claims; risks associated with evolving energy policies in the United States and other countries and the potential costs of regulatory compliance; risks associated with changes to U.S. trade environment; risks resulting from the impact of global pandemics, including the novel coronavirus, Covid-19; our ability to maintain the listing of our shares of common stock on NASDAQ; our ability to grow our business and manage growth profitably, maintain relationships with customers and suppliers and retain our management and key employees; risks related to adverse changes in general economic conditions, including inflationary pressures and increased interest rates; risk from supply chain disruptions and other impacts of geopolitical conflict; changes in applicable laws or regulations; and other risks and uncertainties indicated in the company's most recent annual report on Form 10-K and subsequent reports on Forms 10-Q and 8-K, including those under the heading "Risk Factors" therein, and other factors identified in Eos's prior and future SEC filings with the SEC, available at www.sec.gov. Eos cautions that the foregoing list of factors is not exclusive and not to place undue reliance upon any forward-looking statements, which speak only as of the date made. Eos does not undertake or accept any obligation to release publicly any updates or revisions to any forward-looking statements to reflect any change in its expectations or any change in events, conditions or circumstances on which any such statement is based. Industry an Market Dat In this presentation, we rely on and refer to information and statistics regarding market participants in the sectors in which Eos competes and other industry data. We obtained this information and statistics from third party sources, including reports by market research firms and company filings. We have not independently verified the accuracy or completeness of, and disclaim and liability with respect to, such third-party sources and the data therein that have been included in this presentation. Trademarks This presentation may contain trademarks, service marks, trade names and copyrights of other companies, which are the property of their respective owners. Solely for convenience, some of the trademarks, service marks, trade names and copyrights referred to in this presentation may be listed without the TM, SMⒸ or Ⓡ symbols, but Eos will assert, the fullest extent under applicable law, the rights of the applicable owners, if any, to these trademarks, service marks, trade names and copyrights. Znyth, Eos Znyth, and Eos Z3 are trademarks of Eos Energy Technology Holdings, LLC, wholly owned subsidiary of Eos Energy Enterprises, Inc Key Metrics Backlog. Our backlog represents the amount of revenue that we expect to realize from existing agreements with our customers for the sale of our battery energy storage systems and performance of services. The backlog is calculated by adding new orders in the current fiscal period to the backlog as of the end of the prior fiscal period and then subtracting the shipments in the current fiscal period. If the amount of an order is modified or cancelled, we adjust orders in the current period and our backlog accordingly, but do not retroactively adjust previously published backlogs. We believe that the backlog is a useful indicator regarding the future revenue of our Company. Pipeline. Our pipeline represents projects for which we have submitted technical proposals or non-binding quotes plus customers with letters of intent ("LOI") or firm commitments. Pipeline does not include lead generation projects. Booked Orders. Booked orders are orders where we have legally binding agreements with a Purchase Order ("PO") or Master Supply Agreement ("MSA") executed by both parties.#3First Eos Z3TM Cube Shipped to Customer eos www.#4Operating Highlights Opportunity Pipeline $11.6 billion representing -43 GWh 1 LTD Discharge Energy 1.6 GWh -1.2 GWh in the field (1) Numbers shown as of 9/30/2023 (2) For the nine months ended 9/30/2023 (3) Numbers shown as of 11/03/2023 4 (4) For the three months ended 9/30/2023 Note: GWh are on a rounded basis 3 YTD Booked Orders $92.7 million representing less than ~1 GWh 4 2 Q3 Revenue $0.7 million First Z3 shipments eos Orders Backlog at 9/30 $538.8 million representing ~2 GWh Cash On Hand at 9/30 $58.0 million 1 1 eos.#55 Highlights Developing World Class Partnerships Positioning the Company for long-term success Building Government Support ARIMENT OF E OF AMER Department of Energy STATE OF CALIFORNIA California Energy Commission ENERGY COMMISSION Extensive Due Diligence CALIFORNIA ENERGY COMMISSION Received $399M conditional loan guarantee commitment First Title XVII non-lithium- ion battery manufacturer with conditional loan guarantee commitment Working with CEC since 2014 to utilize Eos Zynth technology Awarded grants / awards in 2014, 2016, 2021, & 2022 Developing Robust Customer Base 3 Major US Utilities ☀ A Blue Chip Customers Duke Energy US Large Utility Dominion Energy ADA ✓ Installed Gen 2.0 pilot project Shipped Z3 en cubes for small commercial project First pilot project (47 MWh) scheduled in 2024 Customer DOE grant application to test Z3 use cases 4 GWh conditional frame agreement 16 MWh pilot project to test longer duration storage Opportunity to showcase Z3 batteries Expanding Strategic Partnerships ACRO Resin MADE IN U.S.A. Foundation to Scale Acro Automation Systems Electrolyte Graphitized Felt ✓ Design, build, and commission state-of-the-art manufacturing lines Develop process capability & world class manufacturing Finalizing long-term supply agreements North American supply chain from raw material to finished product Implementing an integrated strategy from pan fiber to felt eos#6Highlights 6 Balancing Priorities while Meeting Key Customer Commitments Profitability roadmap balances customer deliveries, workforce development, capacity expansion, and capital requirements Original Expectations Financing Z3 Launch Personnel Q1 2023 Manufacturability Supply Chain Development Original 2023 expectation Q2 2023 Q3 2023 Challenges Workforce Development Q4 2023 Manual operations primary defect driver Equipment availability and reliability Date of occurrence Supplier critical part qualification Developing multiple sources of supply Impact + Customer order timing + Working capital and capacity expansion + Customer project readiness + Product cost-out timing Improvements ✓ Detailed training plan - safety, quality, and culture Experienced operators on critical operations ✓ Integrated maintenance planning & routines ✓ Added supply quality and engineering resources ✓ Increased QC inspections Focus Area Working DOE loan closing requirements Comprehensive financing plan Reduce semi-automated production to deliver critical customer commitments Production plan alignment with cost-out program to reduce working capital Deliver state-of-the-art manufacturing line Focus Area Upskill workforce to meet new manufacturing line requirements Implementing Lean Manufacturing Roadmap Adding resources for shift leadership & 24-hour maintenance Weekly critical part reviews with suppliers Further supplier development & multiple sources of supply eos#7Operational Scale & Capacity eos.#8Discrete Operations Semi-Automation State-of-art- Manufacturing Operational Scale & Capacity A Disciplined Approach to Capacity Expansion Iterative learning process to deliver capital efficient state-of-the-art manufacturing Goal 8 1 DAKE 2 3 SOOVRE EXTOL DONCLER B Move from prototype / lab I 1 scale to discrete manufacturing Optimize design Develop processes Low to medium scale production Optimize processes and quality Reduce cost Production at scale Labor optimization Product cost-out + + + + Challenges Cell spacing Bi-polar plate flatness Lid weld integrity and durability Manual operations top scrap driver + Single piece bi-polar production + Learnings + Implement hot plate welding Identify bottlenecks & improve material flow + Controlled workforce ramp-up with experienced workers on critical operations Acro on-site to capture critical lessons learned & incorporate into line design Impact/Successes 50% fewer parts in design 25% savings on injection molded parts Mitigate automation risk Mitigate automation risk Decreased scrap below 5% 5.5x cube production increase in October Faster implementation Lower redesign risks Potential capex savings eos#9Operational Scale & Capacity State-of-the-Art Manufacturing Line Update Station fabrication, process development, and debugging over 30 discrete processes 9 Conceptual Design Integrator evaluations / selection Conceptual design review ✓ Part Presentation Feasibility Study Design for manufacturing the time. ACRO Sub-contractor selection ✓ Detailed Design Mechanical design Controls engineering Bi-polar Insertion 2 FANUC Robot SR-12/A Factory Acceptance Station assembly and integration Mechanical & controls debugging O Site Acceptance 3 Disassemble and ship to Eos factory Final debugging and commissioning Battery Unload ur Beginning to build out full assembly layout inside Acro's facility in Wisconsin av LAST ACRO MADE IN V.S.A. Line 1 Annualized Capacity: -1.25 GWh Investment -1.25 GWh, $30M Includes: Automated Battery Assembly Injection Molding Tools 2+ GWh, Incremental ~$10 - $20M Includes: Terminal / Bi-polar Automation (Supports 2 lines) Final Assembly Automation (Supports 2 lines) Injection Molding Tools On budget and expected commissioning in Q2 2024#10Project AMAZE eos.#11Project AMAZE U.S. Department of Energy Conditional Commitment A $0.5B expansion program with 80% cost reimbursement on eligible costs Conditional commitment term sheet vetted by the Department of Energy and other federal agencies An extensive technical, market, financial, and legal due diligence process with DOE and external experts marks a significant Eos Z3 technology validation milestone Conditional Commitment $398.6 Million ¹ Production Capacity -8 GWh annual capacity by end of 2026 Jan '21 Initial discussions with LPO 11 (1) Represents the maximum guaranteed loan amount (2) Bloomberg NEF 1H 2023 Energy Storage Market Outlook Funding 80% recovery on eligible project costs Interest Rate Based on competitive U.S. Treasury Rates Dec '21 Phase I Title 17 application submitted Feb '22 Eos invited to phase Il application Project AMAZE supports critical U.S. clean energy objectives + + + + + + + May '22 Expanding American clean-tech manufacturing capability qualifying for 45x production tax credit incentives Developing domestic supply chain which is expected to enable customers' IRA 10% domestic content credit Creating U.S. green collar careers Loan would reimburse 80% of eligible capex and opex costs, as spent over program life Closing & funding contingent on meeting certain conditions precedent expected to occur in Q2 2024 Credit subsidy covered by LPO fund appropriation -8 GWh represents only 4% of the U.S. cumulative storage capacity expected by end of 2026² Eos Submits phase II Application Sep ¹22 Eos invited to formal due diligence Aug '23 Conditional commitment approved by LPO eos.#12Project AMAZE Project AMAZE Capacity Expansion 4 manufacturing lines expected to produce 8 GWh of energy storage annually 1H2024 The first state-of-the-art line is expected to be in production in the first half of 2024 e 12 o 1 poo ~1.25 GWh 2H2024-2026 How do you get to 8 GWh? 1.25 GWh is less than the anticipated nameplate capacity of the line Line 1 expected to achieve 2 GWh in production capacity with future sub- assembly automation Additional capacity added as supported by customer demand (OO 2 DOO ~ 2 GWh C 3D C ~ 2 GWh What's the cost of a line? -$40-$50M investment per line for 2+ GWh of production Consist of direct costs associated with ACRO, and injection molding capex ( 4 ) ~ 2 GWh What is PTC ROI? Production Tax Credits (PTC) return up to 125% of capital investments within 1 year of full production IRA tax credits have ability to generate significant source of cash Investment Tax Credits $30-35 $56+ 1.25 GWh ($ in millions) $90+ $40-50 2 GWh#13Commercial Pipeline & Orders Backlog eos.#14Commercial Pipeline & Orders Backlog Value Proposition Shifting to Longer-Duration Storage Use cases beyond 5-hour energy storage favor Eos technology Solar penetration plus electric heating is shifting net peak demand from summer afternoons to winter nights 14 As extreme weather conditions increase, peak demand is becoming more significant in winter than in the summer Summer: Currently, 4-hour discharge is well-suited to providing capacity during summer peaks Winter: Demand peaks may become the primary drivers of resource adequacy needs requiring longer durations ERCOT: Starting to shift to winter peaks as solar production is lower in the winter Solar penetration reducing summer net peaks, while heating increasing winter net peaking requiring longer durations of storage Net Demand (MW) 75,000 70,000 65,000 60,000 55,000 50,000 45,000 40,000 7/20/2022 0:00 Net Den and (MW) 75,000 70,000 65,000 60,000 55,000 50,000 45,000 40,000 12/22 0:00 Summer 7/20/2022 12:00 Summer Net Peak With 2,500 MW Storage - Summer Net Peak 12/22 12:00 7/21/2022 0:00 Winter 7/21/2022 12:00 7/22/2022 0:00 12/23 0:00 Net peak longer -Winter net peak with 2,500 MW of storage Winter net peak 12/23 12:00 12/24 0:00 + System peak load is generally driven by air conditioning during hottest hours + Duration of summer peak increasing, but can usually be offset by increased solar installations + Net peak in winter is typically 8+ hours and can actually be higher total demand than in summer for areas that depend on electric heating Grid will require longer than 4-hour durations of storage to support winter peaks now Eos Z3 system provides the flexibility to be configured for discharging energy from 3 to 12 hrs. Denholm, Paul, Wesley Cole, and Nate Blair. 2023. Moving Beyond 4-Hour Li-Ion Batteries: Challenges and Opportunities for Long(er)-Duration Energy Storage. Golden, CO: National Renewable Energy Laboratory. NREL/TP-6A40-85878. eos#15Commercial Pipeline & Orders Backlog Independent Developer vs. Utility Backed Projects Highlighting two indicative customer types Project Development ✓ Identify opportunity & select technology Perform feasibility studies ✓ ✓ Secure permitting Project Execution INDEPENDENT DEVELOPER Quicker to embrace new technologies ✓ Manage project build process Secure debt &/or equity financing Project Operation Merchant vs. fully contracted Conduct ongoing operations and maintenance (O&M) 15 $ Operator General Framework¹ Investor Investor (1) Represents general framework; specific customer framework may vary Developer Developer $ Developer Operator 1 Detailed Diligence 2 3 4 A- UTILITY BACKED PROJECTS Takes more time to review before committing - 4+ ■ Initial Pilot Project 28.9 M I Pes -$' - Small Commercial Project ■ In-depth tech and financial review Operational data for proof of concept Select technology for non-commercial small installation System operations under field conditions ACA -4. ■ Utility commission awareness Full Scale Approval -☀ ■ H Prove out use cases Eos on approved vendor list Utility commission approved Estimated Timing 9-12 Months 18 - 24 Months 24 - 36 Months 36-48 Months eos#16Commercial Pipeline & Orders Backlog Current Commercial Activity Total current pipeline increased $1.9B vs. Q2 '23 Lead Generation $13B -44 GWh $2.2B vs. Q2 '23 ✓ Feasibility study ✓ Develop project plan ✓ Monitor regulations 1 (1) Numbers shown as of 9/30/2023 16 (2) Numbers shown as of 10/4/2023 with new LOI signed Note: Numbers are rounded Current Pipeline - $11.6B Active proposals $1.6B ~6 GWh Technical proposal $1.9B vs. Q2 '23 $8.4B ~30 GWh Non-binding quote ✓ Clear project requirements ✔ Gather customer specs ✓ Analyze use cases ✓ Commercial & technical proposal 1 LOI / Firm commitments $1.5B/ -7 GWh / (~8 GWh) vs Q2 '23; project moved to backlog ✓ Finalize commercial terms ✓ Contract negotiation ✓ Letter of intent ✓ Open closing conditions 2 Customer next steps + Acquire land rights + Negotiate financing + Establish interconnections Backlog 1 $538.8M ~2 GWh ✓ Binding agreement ✔ Open closing conditions ✓ Purchase orders and/or MSA with down payment Eos next steps + Manufacture batteries + Ship and install system + Monitor performance eos.#17Financial Results eos.#18Financial Results Third Quarter 2023 Eos Income Statement 18 ($ in millions) Revenue Cost of Goods Sold Gross Profit R&D expense SG&A expense Loss from write-off of PP&E Grant expense, net Operating Loss Interest expense, net Change in fair value of derivatives Loss on debt extinguishment Other (income) / expense Income tax expense Net Income (Loss) Q3 2023 Q3 2022 0.7 6.1 21.3 50.0 (20.6) (43.9) 3.2 13.1 1.0 (37.8) 9.4 (61.8) (0.4) 0.0 14.9 4.5 14.7 0.5 (63.6) 5.7 0.4 0.9 I 0.1 (70.7) 6.1 + Revenue $ in millions -89% Q3 2022 0.7 Q3 2023 COGS $ in millions 50.0 Q3 2022 -57% 21.3 Q3 2023 Business Highlights: + Revenue of $0.7M, as the company began delivering initial shipments of its next generation product, Eos Z3™ Costs of Goods Sold of $21.3M driven by lower Z3 product costs, remaining Gen 2.3 spare battery production and $11.2M non-cash items for inventory adjustments, project commissioning timing and depreciation + Operating expenses of $17.3M, a 12% decrease vs. prior year driven by insourcing along with reduced outside services spend + Interest expense increased $3.7 million vs. prior year driven by new debt + Net Income of $14.9 million, primarily resulting from mark to market derivative adjustments eos.#19Financial Results 2023 Outlook Update Clarity around capital affected overall 2023 timing & outlook $600-800M in booked orders $30-50M in revenue 15% product cost reduction from Eos Z3 launch Update Below target Below target Exceed target Eos. Positively ingenious. Eos. Positively ingenious. 19 ■ I ■ ■ ■ Pipeline health and size continuing to improve Selected by Dominion Energy for pilot project -54% of active pipeline created in last 12 months Shipped first commercial Z3 cubes at the end of Q3 Focus on fulfilling critical customer commitments while maximizing product cost curve benefits Partially delivering ERCOT project in Q4 Current Z3 bill of materials exceeds target for early 2024 cut-in Simplified electrolyte formula reduces chemical costs and mixing complexity Developed lower cost enclosure design and contractually secured savings Upcoming Key Events Strategic Outlook Call December 12, 2023 Q4 Earnings Call Late February 2024 Investor Day Tentatively Q2 2024 eos