#10 stem Energy Superintelligence™ Leader in Al-Driven Storage Solutions December 2020#2stem Disclaimer This presentation was prepared exclusively by Goldman Sachs & Co. LLC ("GS") and Credit Suisse Securities (USA) LLC ("Credit Suisse" and, together with GS, "we" or "us") on a confidential basis and is being delivered to a limited number of accredited investors who have agreed to hold it in confidence. This presentation may not be copied or reproduced, or shown to or reviewed with any person other than the intended recipient and its authorized representatives. Confidential 2 Although the information contained herein is believed to be accurate, GS, Credit Suisse and each of the other parties mentioned herein, including for the avoidance of doubt, Star Peak Energy Transition Corp. ("Star Peak") and Stem, Inc. ("Stem”) (as well as each of their respective directors, officers, shareholders, members, partners and representatives), expressly disclaims liability for, and makes no expressed or implied representation or warranty with respect to, any information contained in or omitted from this presentation, or any other information or communication (whether written or oral) transmitted to any prospective investor. Only those representations and warranties made in a definitive agreement with any person shall have any legal effect. PAST PERFORMANCE IS NO GUARANTEE OF FUTURE PERFORMANCE. The recipient of this presentation acknowledges that it is (a) aware that United States securities laws prohibit any person who has material, non-public information concerning a company from purchasing and selling securities of such company or from communicating such information to any other person under circumstances in which it is reasonably foreseeable that such person may purchase sell such securities and (b) that the recipient will neither use, nor cause any third party to use this investor presentation or any information contained herein in violation of the Securities Exchange Act of 1934, as amended, including, without limitation, Rule 10b-5 thereunder. Use of Projections and Financial Information This presentation contains financial forecasts relating to the anticipated future financial performance of Stem, the proposed acquiror and the combined company. For example, projections of future Operating Free Cash Flow, EBIT, EBITDA, Adjusted EBITDA and EBITDA Margin and other metrics are forward-looking statements. Such financial forecasts constitute forward-looking information, are for illustrative purposes only and should not be relied upon as necessarily being indicative of future results. Actual results may differ materially from the results contemplated by the financial forecasts contained in this presentation, and the inclusion of such information in this presentation should not be regarded as a representation by any person that the results reflected in such forecasts will be achieved. Financial Information This presentation also includes references to financial measures that are calculated and presented on the basis of methodologies other than in accordance with generally accepted accounting principles in the United States of America ("GAAP"). Any non-GAAP financial measures used in this presentation are in addition to, and should not be considered superior to, or a substitute for, financial statements prepared in accordance with GAAP. Non-GAAP financial measures should not be considered in isolation and are subject to significant inherent limitations. The non-GAAP measures presented herein not be comparable to similar non-GAAP measures presented by other companies. Stem believes these non-GAAP measures of financial results provide useful information to management and investors regarding certain financial and business trends relating to Stem's financial condition and results of operations. Stem believes that the use of these non-GAAP financial measures provides an additional tool for investors to use in evaluating ongoing operating results and trends in and in comparing Stem's financial measures with other similar companies, many of which present similar non-GAAP financial measures to investors. These non-GAAP financial measures are subject to inherent limitations as they reflect the exercise of judgments by management about which expense and income are excluded or included in determining these non-GAAP financial measures. The financial information and data contained in this Presentation is either audited in accordance with private company auditing standards or is unaudited and, in each case, does not conform to Regulation S-X or Public Company Accounting Oversight Board ("PCAOB") standards. Accordingly, such information and data may not be included in, may be adjusted in or may be presented differently in any proxy statement/prospectus to be filed with the SEC. Other Disclaimers Neither GS nor Credit Suisse has assumed any responsibility for independent verification of any of the information contained herein and GS and Credit Suisse have relied on such information being complete and accurate in all material respects. Accordingly, no representation or warranty, express or implied, can be made or is made by GS or Credit Suisse as to the accuracy or completeness of any such information. Except where otherwise indicated, this presentation speaks as of the date hereof and is necessarily based upon the information available to GS and Credit Suisse and financial, stock market and other conditions and circumstances existing and disclosed to GS and Credit Suisse as of the date hereof, all of which are subject to change. Neither GS nor Credit Suisse has any obligation to update, bring-down, review or reaffirm this presentation. Under no circumstances should the delivery of this presentation imply that any information or analyses included in this presentation would be the same if made as of any other date. Nothing contained in this presentation is, or shall be relied upon as, a promise or representation as to the past, present or future.#3stem Disclaimer Confidential 3 This presentation provides summary information only and is being delivered solely for informational purposes. The recipient of this presentation acknowledges that: 1. GS, Credit Suisse, Star Peak and Stem do not provide legal, tax or accounting advice of any kind. 2. It is not relying on GS, Credit Suisse, Star Peak or Stem for legal, tax or accounting advice, and that the recipient should receive separate and qualified legal, tax and accounting advice in connection with any transaction or course of conduct. 3. Nothing contained herein shall be deemed to be a recommendation from GS, Credit Suisse, Star Peak or Stem to any party to enter into any transaction or to take any course of action. This presentation is not intended to provide a basis for evaluating any transaction or other matter. 4. 5. This presentation is confidential and may not be copied by, or disclosed or made available to, any person without the prior written consent of GS and Credit Suisse. 6. None of GS, Credit Suisse, Star Peak or Stem shall have any liability, whether direct or indirect, in contract or tort or otherwise, to any person in connection with this presentation. In connection with the proposed business combination between Star Peak and Stem (the "Business Combination"), Star Peak intends to file with the Securities and Exchange Commission (the "SEC") a registration statement on Form S-4 containing a preliminary proxy statement and a preliminary prospectus of Star Peak, and after the registration statement is declared effective, Star Peak will mail a definitive proxy statement/prospectus relating to the proposed Business Combination to its stockholders. This presentation does not contain all the information that should be considered concerning the proposed Business Combination and is not intended to form the basis of any investment decision or any other decision in respect of the Business Combination. Star Peak's stockholders and other interested persons are advised to read, when available, the preliminary proxy statement/prospectus and the amendments thereto and the definitive proxy statement/prospectus and other documents filed in connection with the proposed Business Combination, as these materials will contain important information about Star Peak, Stem and the Business Combination. When available, the definitive proxy statement/prospectus and other relevant materials for the proposed Business Combination will be mailed to stockholders of Star Peak as of a record date to be established for voting on the proposed Business Combination. Stockholders will also be able to obtain copies of the preliminary proxy statement/prospectus, the definitive proxy statement/prospectus and other documents filed with the SEC, without charge, once available, at the SEC's website at www.sec.gov, or by directing a request to: Star Peak Energy Transition Corp., 1603 Orrington Avenue, 13th Floor, Evanston, IL 60201. Star Peak and its directors and executive officers may be deemed participants in the solicitation of proxies from Star Peak's stockholders with respect to the proposed Business Combination. A list of the names of those directors and executive officers and a description of their interests in Star Peak is contained in Star Peak's final prospectus related to its initial public offering dated August 17, 2020, which was filed with the SEC and is available free of charge at the SEC's web site at www.sec.gov or by directing a request to: Star Peak Energy Transition Corp., 1603 Orrington Avenue, 13th Floor, Evanston, IL 60201. Additional information regarding the interests of such participants will be contained in the proxy statement/prospectus for the proposed Business Combination when available. Stem and its directors and executive officers may also be deemed to be participants in the solicitation of proxies from the stockholders of Star Peak in connection with the proposed Business Combination. A list of the names of such directors and executive officers and information regarding their interests in the proposed Business Combination will be included in the proxy statement for the proposed Business Combination when available. INVESTMENT IN ANY SECURITIES DESCRIBED HEREIN HAS NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND EXCHANGE COMMISSION OR ANY OTHER REGULATORY AUTHORITY NOR HAS ANY REGULATORY AUTHORITY PASSED UPON OR ENDORSED THE MERITS OF THE OFFERING OR THE ACCURACY OR ADEQUACY OF THE INFORMATION CONTAINED HEREIN. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE. THIS PRESENTATION DOES NOT CONSTITUTE AN OFFER OR SOLICITATION OF ANY SECURITIES. STAR PEAK WILL MAKE ANY OFFER TO SELL SECURITIES ONLY PURSUANT TO A DEFINITIVE SUBSCRIPTION AGREEMENT, AND STAR PEAK RESERVES THE RIGHT TO WITHDRAW OR AMEND FOR ANY REASON ANY OFFERING AND TO REJECT ANY SUBSCRIPTION AGREEMENT IN WHOLE OR IN PART FOR ANY REASON.#4stem Transaction Summary Star Peak has identified Stem as a market leader in the clean energy ecosystem Leader in Al-Driven Storage Solutions The Business Offering Size Valuation Capital Structure Stem's Investors IBERDROLA TEMASEK ● ● ● ● ● Founded in 2009, Stem is an industry leading Al-driven storage solutions business TOTAL Star Peak Energy Transition Corp. (NYSE: STPK) is a special purpose acquisition company with over $383MM of cash in trust PIPE size of $225MM Pro forma equity value of $1.4B Attractively valued entry multiple Stem shareholders rolling 100% of their equity ~$525MM net cash (assuming no redemptions) retained to fully finance all forecasted growth MITHRIL Activate capital Constellation RWE Anion Company ANGELENO GROUP ONTARIO TEACHERS' PENSION PLAN MITSUI & CO. copec GE Leadership stem ^^ STAR PEAK John Carrington CEO & Director Eric Scheyer CEO € Larsh Johnson CTO Mike C. Morgan Chairman Confidential Bill Bush CFO Adam Daley Director 4#5stem Star Peak Mission & Summary Star Peak overview Magnetar Capital and Triangle Peak Partners Experienced Sponsor with Proven Track Record Mike C. Morgan Chairman • Co-founding partner, Chairman, and CEO of Triangle Peak Partners, LP ● ● Founding team member at Kinder Morgan, Inc. (NYSE: KMI), former President, current Lead Director of KMI Former Lead Director, current Director of Sunnova Energy International (NYSE: NOVA) Co-Chair, Stanford Precourt Institute Energy Advisory Council Successful investment track record (1) >12yrs $6B PARTNERSHIP HISTORY EQUITY CAPITAL COMMITTED (1) Star Peak Energy Transition Corp. as of 9/30/2020. Eric Scheyer CEO Head of Magnetar Energy & Infrastructure Group since its inception in 2005 ● ● ● Member of Magnetar Investment Committee & Management Committee Former Director, Arc Logistics (NYSE: ARCX) 64 PRIVATE INVESTMENTS 48 VENTURE CAPITAL DEALS Star Peak's Climate Focused Mission Backed by Compelling Economics Provide growth capital to a market-leading business focused on climate change initiatives, emissions reductions, and energy efficiency ● RENEWABLES EV Capitalize on scarcity of high quality, public companies with attractive ESG characteristics INFRASTRUCTURE ENERGY STORAGE TECHNOLOGY Confidential ELECTRIC VEHICLES TRANSPORTATION TECHNOLOGY SUPPLY CHAIN & LOGISTICS FOOD TECHNOLOGY LO 5#6stem Our Vision: Smart Storage is Key to Global Decarbonization Climate Change is the problem 27% Electricity production is the #2 polluter responsible for 27% of greenhouse gas emissions (1) 3x Natural catastrophe-related loss events since 1980(2) Risk Investors recognize climate change is one of the biggest risks impacting businesses (3) 60% Fossil fuels still accounted for 60% of global electricity generation in 2019(4) 72% Companies actively publicize their sourcing of renewable energy(5) $200bn Over $200bn cumulative inflows into ESG funds since the beginning of 2019 versus ~$600bn cumulative outflows from non-ESG funds(6) Confidential (1) EPA: Sources of Greenhouse Gas Emissions report, Sep-2020. (2) Wall Street Research. (3) World Economic Forum. (4) British Petroleum. (5) Deloitte Insights, "Deloitte Resources 2019 Study." (6) EPFR Global. 6#7stem Our Vision: Smart Storage is Key to Global Decarbonization A revolutionized grid, with Stem, is the solution Grid Since 2019, 90% of new interconnection requests were renewables and/or storage, but renewable generation suffers from intermittency(1) Distributed, renewable generation is supplementing and replacing traditional generation (1) Wood Mackenzie Energy Storage Service. (2) Bloomberg New Energy Finance. Storage ÒÒÒ Battery production is becoming cheaper and more commercialized STEM |||| Energy storage is key to the build out of renewable generation, and represents a $1.2 trillion revenue opportunity through 2050(2) 1 Confidential 7 Battery optimization is difficult. Energy intelligence amplifies performance by anticipating demand cycle, energy prices, generation profile and other factors in real time#8stem Investment Highlights Stem is the first pure play smart energy storage company to go public in the US Large Addressable Market + Strong Macro Tailwinds ~$1.2 trillion in new revenue opportunities for integrated storage expected to be deployed by 2050(¹) Battery storage capacity expected to increase by 25x by 2030 (²) Market Leader with Best in Class Technology 900+ systems operating or contracted with Stem's Athena software (3) 75% market share in CA BTM storage market, largest in the US(2) First mover Al platform that operates with 40+ utilities, 5 grid operators and over 16MM runtime hours (1) Bloomberg New Energy Finance. (2) Wood Mackenzie. (3) As of 31-Oct-2020. Balance Sheet Positioned to Capitalize on Growth Ready to deploy net cash balance of ~$525m to target and fund high growth markets Transaction fully finances all forecasted growth Highly Visible Growth Confidential Recurring revenue streams provide strong financial position to accelerate growth Revenues projected to grow at ~51% CAGR from 2021 to 2026 8#9stem Stem Introduction Hardware + Network Integration ✓ Tier 1 standard hardware solutions Smart Energy Storage Drives The Grid Transformation Lowers Energy Costs ļi Software ✓ Battery optimization via Athena Al athena powered by stem Stabilizes the Grid Reduces Carbon Emissions DIN AN Solves Intermittency 27 Confidential Market Participation ✓ Upside sharing through sales into energy markets 9 Creates VPPs and Storage Networks#10stem Network Effect and Intelligence Drives Value Stem operates the world's largest network of energy storage systems Confidential As cumulative installs grow, Athena becomes more intelligent, creating more value and a larger moat 10#11stem Global Commitment to Decarbonization With the world committed to decarbonization, Stem is well positioned to capture this tailwind. UTILITIES & ASSET OWNERS CMS ENERGY Portland General Electric Southern AVISTA Company AUSTIN ENERGY AMERICAN ELECTRIC POWER WEC Energy Group Ⓡ Source: Company filings, EEI, S&P Global Market Intelligence. NorthWestern PG E Ameren PSEG eXcel Energy HEI Pacific Gas and Electric Company' DTE SMUD Paris Accord California mandates zero non-EV passenger vehicle sales by 2035 Energy Delivering a Bright Future Entergy. NiSource Dominion Energy EDISON INTERNATIONAL Energy for What's Ahead" DUKE ENERGY. FERC 841/ FERC 2222 Alliant Energy CROSS stem AVANGRID NY, MA, VA set multi-GW energy storage targets ENERG Japan net zero emissions pledge f HOME DEPOT . REGULATORS Walmart Cargill The California State University amazon CSU ups Alphabet IHG OWENS CORNING WELLS FARGO Confidential 11 • CORPORATES#12stem Historical Power Sector is Being Transformed HISTORICAL POWER SECTOR Confidential 100 Generation Substation End Consumers Transmission 12#13stem The Grid is Being Transformed, Decentralized and Democratized More distributed Power used to be all bulk centralized generation...now it is distributed and islanded to enhance reliability & resilience - requiring new solutions and business models More complex Power used to flow in one direction... now it flows bi-directionally requiring new coordination and optimization systems More dynamic Power used to be predictable and controllable...now it is generated from a multitude of intermittent assets - requiring intelligent, adaptable 24/7 management Source: McKinsey. STEM AI POWER SECTOR Intermittent Generation Distributed Generation STEM Confidential 13 100 Generation Substation End Consumers Transmission#14Levelized Cost of Energy ($/kW) stem Clean Energy Technology Convergence: Disruption and Exponential Growth Renewables Lowest Cost Generation $ 400 $300 $ 200 $100 $0 + 2010 2012 2014 2016 2018 2020 Nuclear Wind Coal Solar PV CCGT BESS hardware cost (US$/kWh) Battery Hardware Rapid Cost Reductions $300 $260 $220 $180 $140 $100 $280 $246 $210 $171 $145 $129 $117 2018 2020 2022 2024 2026 2028 2030 Capacity GWh Storage Market 25x Growth" Market Opportunity $1.2 Trillion 200 160 120 80 40 0 6 11 Confidential 30 United States 40 62 101 Rest of World 14 2018 2020 2022 2024 2026 2028 2030 164 800 600 400 200 0 Cumulative Capacity GWh (3) Cumulative Capacity Source: Bloomberg New Energy Finance, Wood Mackenzie, Lazard LCOE. Note: BESS includes battery rack, PCS, balance of system, energy management system and transformer costs. (1) Wood Mackenzie. (2) Bloomberg New Energy Finance. (3) Includes all FTM, non-residential and residential storage.#15$ BILLIONS stem Stem is a Market Leader with Significant Scale and Visible Growth Stem is a Leader in Deployments Worldwide(¹) One of the Top Systems Integrators by Disclosed Commissioned Projects 2014-3Q20 Storage Capacity Commissioned (MWh) 0 100 200 300 400 Stem's Total Pipeline Growth 125% Pipeline Growth Since Q3 2019 3.0 2.5 2.0 1.5 1.0 0.5 500 $1.2B 600 Q3 2019 700 stem Tesla, Inc Hyundai Electric Fluence Energy Nidec Corp NEC Corp Mitsubishi Electric +125% $2.7B ● Q3 2020 ● stem S stem 900+ systems operating or contracted (~1 GWh) (²) Systems operating in ● • 75 jurisdictions 200+ cities ● ● ● Confidential stem WINE $800MM Q3 2018 Note: Includes only lithium ion providers. (1) Bloomberg New Energy Finance - Storage Assets Interactive Dataset; Reflects System Integrators by Capacity (MWh), filtered by Commissioning Date and Commissioned Status as of 11/04/2020; Stem data from Company. (2) As of 31-Oct-2020. (3) Wood Mackenzie. 75% BTM market share in California, largest storage market in the US(3) $145MM bookings in 2020E ~4.5x revenue growth in 2021E#16ATHENA CUMULATIVE RUNTIME HOURS stem Stem's Athena Al Platform is Built On 3 Generations and >10 Years of Data + Experience Confidential 16 900+ sites & ~1 GWh in operation & contracted(1) 20M 16M 12M 8M 4M ■ OM 2014 2015 Gen 1 2009-2015 5+ years inventing the market First to market with C&I storage First Hawaii Electric VPP First California ISO wholesale market participation Source: Stem. (1) As of 31-Oct-2020. 100+ sites in operation 2016 400+ sites & 100 MWh in operation 2017 Gen 2 2016 - 2018 2+ years commercial growth ▪ First storage VPP for California Resource Adequacy & distribution deferral ■ ▪ First municipal storage VPP with Austin Energy First C&l storage in Arizona First storage VPP in Japan 2018 2019 Gen 3 2019 2020 2+ years accelerating growth ■ First Stem as a service contract via SK SUSI RFP award ■ 2020 ▪ Serving 40 utilities & markets ▪ Delivering multiple value streams in Ontario market Partnering with solar IPP & energy market Supplying backup power >20,000 market dispatches/year ■#17stem Athena: Best-in-Class Al Software Platform 24 PATENTS GRANTED COVERING STEM'S SOFTWARE AND STORAGE SITES Commercial Industrial Independent Power Producer Utility ATHENA EDGE PLATFORM Real-time Control Data Acquisition Site Monitoring Asset Management DATA INTEGRATION Weather Prices ATHENA ANALYTICS Forecast Optimize Learn & Train ATHENA CLOUD PLATFORM ✓ Energy Price Management Program Management Site & Customer Data Markets Grid ATHENA PORTAL Value Modeling & Simulations Dashboards Status ATHENA GATEWAY Utility & Market Integrations MONITORING REPORTING DATA APIs PROTOCOLS & APIs Confidential 17 USERS & Customers Partners Utilities Markets#18stem Athena Platform Delivers Value to Multiple Customer Segments Stem's Customer. Services Stem offers more value streams in more markets with more asset types Al-Driven Athena platform facilitates monetization of 11 out of 13 identified energy storage value streams Source: Rocky Mountain Institute. ER SERVICES ITC & PV Self- Consumption (ITC) Demand Charge Reduction (DCM) Time-of- Use Bill Management Distribution Deferral Backup Power Energy Arbitrage (EA) Spin / Non-Spin Reserve UTILITY SERVICES Transmission Transmission Congestion Deferral Relief ISO/RTO SERVICES Frequency Regulation Voltage Support Black Start Resource Adequacy Confidential Stem's Virtual Power Plant & FTM Services Services that Stem is currently offering 18#19stem Athena Platform Delivers Resource Adequacy in the California Market AGGREGATE SYSTEM POWER - KW 40,000 30,000 20,000 10,000 0 -10,000 - -20,000 - -30,000 -40,000 -50,000 -60,000 CHARGING FROM GRID DISCHARGING TO GRID 09:00 12:00 15:00 18:00 21:00 Its Electric Grid Under Strain, California Turns to Batteries New York Times "On Friday, Aug. 14, the first day California ordered rolling blackouts, Stem, an energy company based in the San Francisco Bay Area, delivered 50 megawatts — enough to power 20,000 homes from batteries it had installed at businesses, local governments and other customers. " 00:00 03:00 06:00 09:00 12:00 Confidential 19 SK SUSI select Stem Competitive RFP in 2020 to select software provider for 345 MWh 25 Tier 1 commercial and municipal customers in Los Angeles and Southern California Edison service territory Stem beat 10 bidders, including energy services firms, based on Athena's advanced Al capability, demonstrated record of success and world-class management team as key differentiators SK E&S SUSI PARTNERS SUSTAINABLE INVESTMENTS#20stem Stem Delivers a Strong Value Proposition to Customers BEHIND THE METER "BTM" FRONT OF THE METER "FTM" COMMERCIAL & INDUSTRIAL Reducing Consumer Energy Bill Athena Al optimizes time-of-use and demand charges, resulting in 10% - 30% monthly electricity bill reductions Corporate ESG Objectives 35% of Fortune 500 have committed to carbon neutrality(1) UTILITIES, IPPS, DEVELOPERS Increasing Asset Returns Athena Al enables solar generation time-shifting and participation in ancillary revenue streams, resulting in 10% - 30% unlevered IRRS Supports Grid Stability Athena Al reduces volatility and supports local grid capacity needs 2,500 2,000 1,500 1,000 - 500 0 (500) (1,000) (1,500) 09:30 13:00 16:30 20:00 2,000 1,000 0 (1,000) (2,000) (3,000) Discharging when prices are high (4,000) (5,000) Battery Charging when prices low Charging when prices low Battery 23:30 03:00 06:30 Time of Day Facility 10:00 13:30 17:00 Grid Sees (2) Discharging when prices are high 09:30 12:00 14:30 17:00 19:30 22:00 00:30 03:00 05:30 08:00 Time of Day (2) O Solar Generation Grid Sees OWENS CORNING HOME DEPOT Confidential 20 WELLS FARGO Cargill amazon CSU State University IHG Walmart Alphabet AMERESCO Greenskies syncarpha capital o ups f ONYX DSDI SUMMIT ENERGY Source: Stem (1) Natural Capital Partners. (2) In the top chart, Grid Sees is the net power draw from the grid after the activity of the battery; In the bottom chart, Grid Sees is the net delivery to the grid including the activity of the battery.#21stem Industry Leading Reach And Unmatched Sales Network Direct sales Drives demand and "spec in" Stem solutions into enterprise procurement solicitations amazon Walmart SIMON ups Deep relationships across the Fortune 500 Sales channel partners Sells into commercial customers S PFMG SOLAR FOREFRONT POWER Greenskies ONYX 500+ sales executives across EPC / developer channels with Stem University Distributors Reach broad based solar, electrical, building automation, HVAC market WERNER Soligent ELECTRIC SUPPLY CED GREENTECH BayWar.e. Distributor relationships cover entire US market Confidential Large renewable project developers Drive demand within project developer and financing ecosystem AMERESCO DSDI syncarpha capital SUMMIT ENERGY 21 Consistently delivering differentiated returns to renewable asset managers#22stem Strong Balance Sheet Drives Rapid Expansion Net Cash Available for Growth ~$525MM Debt on Balance Sheet $0 (1) (1) Pro forma for transaction. Balance Sheet Strength Supports credit requirements to convert large projects in pipeline Supply Chain Savings Capital to further reduce cost structure with OEMs Geographic Expansion Expansion into rapidly growing international markets with new and existing partners Confidential 22 Athena Expansion & Tech Acquisitions Product development to further extend Athena Al leadership position and accelerate roadmap Joint Venture Opportunities Capture enhanced economics#23stem Exceptional Leadership Team John Carrington CEO and Director Larsh Johnson Chief Technology Officer • Seasoned leadership team SIEMENS eNGie with 150+ years of experience in the software and energy space Leadership experience at technology, energy, and industrial companies • 145 employees Source: Stem. REC SOLAR Bill Bush Chief Financial Officer BORREGO SOLAR SOLAR SEMICONDUCTOR First Solar. TPG NEWBRIDGE MiaSolé. REDAPTIVE™ A Hanergy Compony ANGELENO GROUP 1803 R Mark Triplett Chief Operating Officer D Dnn (GE Alan Russo Chief Revenue Officer Sylvia Lan Senior Director, HR Confidential Majority Independent Board 1. John Carrington (Stem) 2. Anil Tammineedi (Stem) 3. David Buzby (Stem) 4. Mike Morgan (Star Peak) 23 Prakesh Patel VP of Capital Markets & Strategy 5. TBD (Stem Designee) 6. TBD (Stem Designee) 7. TBD (Star Peak Designee)#24stem Section 2 Financial Forecast 24#25stem Hardware Deliveries Drive Strong Recurring Software Cash Flows Hardware + Network Integration Total Deliveries (kWh) (x) Project Hardware ASP ($kWh) = Total Hardware Revenues ~10-30% Hardware Gross Margin ✓ Upfront payment for initial purchase ✓ Hardware agnostic platform ✓ Turnkey approach with focus on customer value Source: Stem. athena powered by stem Software Total AUM (kWh) (x) Software Subscription ($/kWh/month) Total Software (Recurring) Revenues ~80% Software Gross Margin ✓ Recurring SaaS model ✓ 100% attach rate secured by 10-20 year contracts with monthly recurring cash flow ✓ Revenue recognized ratably during life of the contract ✓ Additional upsell revenue from Athena applications PER OF O 424 Confidential Market Participation Total AUM (kWh) (x) Stem's Market Participation Revenues ($/kWh) = Total Software (Variable) Revenues ~80% Market Participation Gross Margin 25 ✓ Revenues from differentiated Athena capabilities and VPPs ✓ Secured by 3-20 year contracts ✓ Revenue recognized when realized ✓ Significant long term value#26stem Revenue Contribution Case Study Illustrative project revenue contribution Case Study ● ● Front of the Meter, New York Market Hardware + Software 5 MW / 20 MWh Standalone Storage Solution ~$10MM customer lifetime value Delivery Hardware + Network Year 1-20 Software Revenue(1) Confidential 26 10% 30% 60% Total Revenue Market Participation (2) Variable Recurring Upfront Source: Stem. Note: Values estimated based on historical experience and consultant forecasts. (1) Average of $0.84 / kWh per month (Year 1-20) starting at $0.39/kWh per month with annual escalator. (2) Average of $0.33/kWh per month (Year 1-20).#27stem Bookings, Deliveries, and Revenues Business scales with accelerating storage adoption Bookings & Deliveries (¹) (MWh) 8,000 6,000 4,000 2,000 0 129 64 197 92 321 81 615 2018A 2019A 2020E 2021 E Bookings 1,360 332 3,195 708 4,260 2,031 ■ Deliveries 5,593 3,472 7,183 4,577 5,965 2022E 2023E 2024E 2025E 2026E Bookings & Revenues ($MM) $1,200 $900 $600 $300 $0 Software and market participation growth driven by recurring software revenue streams and expanding market participation $76 $88 $145 $7 $17 $ 198 $33 $ 342 ■ Bookings ■ Hardware Revenue $147 $ 721 $315 $ 848 $ 526 Confidential 27 $1,159 $1,167 $974 $ 748 $944 2018A 2019A 2020E 2021E 2022E 2023E 2024E 2025E 2026E Software Revenue ■ Market Participation Revenue Source: Stem. Note: Bookings represent value of executed customer contracts excluding Market Participation revenue. Stem total revenue calculation assumes recognition of all contracted backlog at system delivery and ratable recognition of software services over the contractual period; Hardware revenue assumes all contracted backlog recognized at system delivery; Software revenue includes SaaS Fees, revenue within the period from systems on balance sheet and O&M. (1) Excludes ~350MW of deliveries and bookings from Q32020 SK SUSI contract and excludes software bookings and deliveries.#28stem Overview of 2021 Revenue Coverage Bookings underpin significant visibility of 2021 $ 400 $300 $200 $100 $0 Source: Stem. $130 ■ Contracted Revenue $241 ~88% from executed contracts >14x coverage on remaining 12% of revenue target $147 Near-term Pipeline Revenue All figures above as of end of October 2020 ■2021E Revenue Confidential 28 Current Contracted Backlog 140 Projects in Process 43 Customers 2.5 MWh Average System Size#29stem Revenue Diversity Robust revenue growth by customer type and segment By Customer Type ($MM) $1,500 $1,200 $900 $600 $300 $0 $33 $147 $315 $526 $748 ■FTMBTM $944 $1,167 2020E 2021E 2022E 2023E 2024E 2025E 2026E By Segment ($MM) $1,500 $1,200 $900 $600 $300 $0 $ 33 $147 81% CAGR $315 $ 526 $748 $944 $ 1,167 2020E 2021E 2022E 2023E 2024E 2025E 2026E By Software Type ($MM) $300 $225 $150 $75 $0 Market participation revenue expands to ~28% of total software revenue by 2026, providing significant long term value $14 $17 $24 Confidential 29 $44 $83 $144 ■Hardware Revenue Software Revenue Market Participation Revenue 2020E 2021E 2022E 2023E 2024E 2025E 2026E $241 Source: Stem. Note: Stem total revenue calculation assumes recognition of all contracted backlog at system delivery and ratable recognition of software services over the contractual period; Hardware revenue assumes all contracted backlog recognized at system delivery; Software revenue includes SaaS Fees, revenue within the period from systems on balance sheet and O&M.#30stem Gross Margins Gross margin expands with increasing scale and software growth Pro Forma Gross Profit by Type ($MM)(¹) $600 $450 $300 $150 $0 As Stem's AUM grows, software becomes material portion of gross profit $4 2020E $ 24 2021E $82 2022E $169 2023E $ 264 2024E $360 2025E ■ Hardware Gross Profit ■ Software Gross Profit $ 483 2026E Gross Margins Driven by Increasing Software Margin(²) 60 % 45 % 30% 15% 0% ∞ 18% 00 18 % 12% 2018A 2019A 2020E 16% 2021E Confidential 26% 32% Software Gross Margin 35 % Blended Gross Margin 38% Hardware Gross Margin 2022E 2023E 2024E 30 41% 2025E 2026E Source: Stem. (1) Stem total gross profit calculation assumes recognition of all contracted backlog at system delivery and ratable recognition of software services over the contractual period; Hardware gross profit assumes all contracted backlog recognized at system delivery; Software gross profit includes SaaS Fees, gross profit within the period from systems on balance sheet, O&M and ongoing Market Participation gross profits. (2) Historical gross margin adjusted for non-recurring and non-system related items.#31stem Financial Forecast Stem delivers consistent growth and improving margins ($MM) Cumulative AUM (MWh) Yo Y Growth Bookings YOY Growth Revenue YOY Growth Pro Forma Gross Profit Gross Margin(1) Total Operating Expenses Adjusted EBITDA EBITDA Margin % CapEx Free Cash Flow FY20E 714 153% $145 65% $33 94% $4 12% 39 ($35) NM NM NM FY21E 1,046 46% $198 37% $147 348% $24 16% 49 ($25) NM ($17) ($49) FY22E 1,754 68% $342 72% $315 115% $82 26% 54 $28 9% ($34) ($7) FY23E 3,785 116% $721 111% $526 67% $169 32% 55 $113 22% ($39) $70 FY24E 7,257 92% $848 18% $748 42% $264 35% 60 $204 27% ($37) $162 FY25E ~88% of Forecasted 2021 Revenues From Executed Contracts Source: Stem. Note: Stem's fiscal year is 31-Dec. (1) Pro Forma Gross Profit adjusted for non-recurring, non-system related items and amortization related with product development (IDS) costs. 11,834 63% $974 15% $944 26% $360 38% 65 $295 31% ($35) $253 Confidential 31 FY26E 17,799 50% $1,159 19% $1,167 24% $483 41% 66 $417 36% ($25) $381#32stem Detailed transaction overview Transaction Highlights Cash Sources Valuation Capital Structure ● Pro Forma Ownership at $10.00/Share(1) Star Peak has ~$383MM in cash held in the trust account PIPE size of $225MM Attractive entry multiple relative to clean energy peer group ~$525MM net cash to balance sheet (assuming no redemptions) to fund growth Star Peak Public Shareholders 28.3% PIPE Shareholders 16.6% Star Peak Sponsor 7.1% Stem Management Shareholders 4.6% (2) Stem Shareholders (2) 43.4% Sources and Uses Sources Committed Equity PIPE Star Peak Trust Stem Shareholder Equity Rollover Total Sources Pro Forma Valuation Pro Forma Shares Outstanding Share Price Stem Equity Value Pro Forma 3Q20 Net Debt (Cash) Stem Enterprise Value Pro Forma Ownership Ownership Breakdown Stem Shareholders(4) Star Peak Public Shareholders Star Peak Sponsor PIPE Shareholders Equity Ownership $MM % 225 17.9% 383 30.4% 650 51.7% $ 1,258 Confidential 32 Uses Stock to Stem Shareholders Estimated Fees and Expenses Estimated Repayment of Debt (3) Cash to Stem Balance Sheet Total Uses $MM 650 51 45 512 $ 1,258 Shares (MM) 65.0 38.3 9.6 22.5 135.4 Source: Stem, Star Peak. (1) Pro forma ownership structure based on PIPE of $225MM, assuming no redemptions. Excludes Star Peak warrants. (2) Stem shareholdings includes common and preferred equity as well as warrants and equity which may be net settled at the transaction date. (3) $45MM debt pay down reflects repayment of all outstanding indebtedness at closing (inclusive of make whole). (4) Equity value to Stem's existing shareholders is calculated as $650MM at $10.00 share price. % 51.7% 4.1% 3.6% 40.7% 135.4 $10.00 $1,354 (525) $829 % 48.0% 28.3% 7.1% 16.6% 100.0%#33stem Public comparable universe Solar Technology Solutions Stem Peers Relevance to Stem ARRAY ENPHASE TECHNOLOGIES ● solaredge Robust upfront cash generation Serves similar end markets Distributed Solar ● sunnova SUNPOWERⓇ sunrun Diversified long-term contracted cash flows Increasing BTM storage attachment rates ● ● Sustainable Infrastructure ● ● Bloomenergy -chargepoin+ • ESG-friendly High growth supported by large TAM Strong fundamental tailwinds Scarcity premium Upfront equipment margins augmented by recurring cash flows stem Confidential Diversified Energy Tech TESLA ● Emphasis on FTM and BTM energy storage business 33#34stem Operational Benchmarking Operational benchmarking Revenue Growth Gross Margin EBITDA Margin stem ~ 350% 2021E 16% 2021 E NM 2021E 115% 2022E 26% 2022E 9% 2022E 67% 2023E 32% 2023E 22% 2023E CY 2021E Financials 14% ARRAY TECHNOLOGIES 22% ARRAY TECHNOLOGIES 17% ARRAY TECHNOLOGIES 63% e ENPHASE 38% 22% 26% solaredge 33% e ENPHASE solaredge 19% 31% sunnova solaredge e ENPHASE Solar Technology Solutions 60% sunnova 80% (1) sunnova 26% SUNPOWER® 18% SUNPOWER 9% 53% SUNPOWER® Distributed Solar 27% sunrun sunrun Bloomenergy -chargepoin+ NM sunrun 29% Source: Stem, Bloomberg, CapIQ, IBES consensus estimates, analyst estimates and company disclosures; market data as of 01-Dec-2020. (1) Sunnova EBITDA adjusted to include loan business income (principal and interest). (2) Chargepoint forward-looking metrics based on management estimates. 27% 47% 12% (2) 31% (2) Bloomenergy -chargepoint NM Bloomenergy -chargepoin+ Sustainable Infrastructure (2) 46% Confidential 34 TESLA 22% TESLA 19% TESLA Median: 31% Median: 27% Median: 18% Diversified Energy Tech#35stem Valuation Benchmarking Valuation benchmarking EV / Revenue stem" 2021E 2022E 2023E 2024E 2025E 2026E 1.6 x 1.1 x 0.9 x 2.6 x 0.7 x 5.6 x CY 2021E EV / Revenue 5.7x (2) ARRAY TECHNOLOGIES 4.9 x (2) 13.5 x CY 2022E EV / Revenue ARRAY TECHNOLOGIES e ENPHASE solaredge 8.1 x 10.7 x e ENPHASE 6.7 x solaredge Solar Technology Solutions 27.7 x 3.0 x sunnova SUNPOWER 20.4 x 2.6 x sunnova SUNPOWER® Distributed Solar 11.8 x sunrun 10.7 x 5.2 x 41.9 x 4.2 x (3) Bloomenergy chargepoint 24.0 x (3) Bloomenergy chargepoint sunrun Sustainable Infrastructure 14.3 x TESLA 11.7 x TESLA 5.6 x Confidential 35 2.6 x (1) istem istem Diversified Energy Tech (4) Median: 11.8 x Median: 10.74) Source: Stem, Bloomberg, CapIQ, IBES consensus estimates, analyst estimates and company disclosures; market data as of 01-Dec-2020. (1) Based on Stem enterprise value $829MM. (2) Array enterprise value calculated using pro forma debt and cash figures from S-1 (as of 13-Oct-2020). (3) Based on Chargepoint EV of $8.3B; forward-looking metrics based on management estimates. (4) Median calculation excludes Stem.#36stem Valuation Benchmarking (cont'd) Valuation benchmarking (cont'd) EV / EBITDA stem" 2021E NM 2022E 2023E 2024E 2025E 2026E 7.3 x 4.1 x 2.8 x 2.0 x 29.1 x CY 2021E EV / EBITDA 33.1 x (2) ARRAY TECHNOLOGIES 29.0 x (2) 52.1 x ARRAY TECHNOLOGIES e ENPHASE CY 2022E EV / EBITDA 40.0 X 42.9 x e ENPHASE solaredge 33.9 x solaredge Solar Technology Solutions 34.7 X ● 23.9 x (3) sunnova SUNPOWER 33.6 x (3) 22.6 x NM Distributed Solar sunrun NM sunnova SUNPOWER' sunrun 43.9 x NM 27.4 x Bloomenergy chargepoint (4) NM (4) Bloomenergy-chargepoint Sustainable Infrastructure 75.1 x TESLA 60.3 x TESLA NM Confidential 36 stem 29.1 x (1) istem Diversified Energy Tech (5) Median: 42.9 x (5) Median: 29.0 x Source: Stem, Bloomberg, CapIQ, IBES consensus estimates, analyst estimates and company disclosures; market data as of 01-Dec-2020. (1) Based on Stem enterprise value of $829MM. (2) Array enterprise value calculated using pro forma debt and cash figures from S-1 (as of 13-Oct-2020). (3) Sunnova EBITDA adjusted to include loan business income (principal and interest). (4) Based on Chargepoint EV of ~$8.3B; forward-looking metrics based on management estimates. (5) Median calculation excludes Stem.#37stem Stem Valuation Stem has significant upside potential Enterprise Value ($MM) Source: Stem. Post-Money $ 829 Enterprise Value $2,836 185% Midpoint Premium $1,891 6.0x - 9.0x 2022E Revenue Confidential 37#38stem Strong Balance Sheet Drives Rapid Expansion Investment thesis Stem is the first pure play smart energy storage company to go public in the US ✓ ✓ Large Addressable Market and Strong Macro Tailwinds Market Leader with Industry Leading Technology Balance Sheet Well Positioned to Capitalize on Significant Expected Growth ✓Highly Visible Growth to Gain ✓ Exposure to Energy Transition and ESG 38#39stem Appendix A Supplemental Information#40stem Definitions Item Pipeline Booking Backlog Behind-the-meter ("BTM") Front-of-the-meter ("FTM") Hardware Revenue Software Revenue Market Participation Revenue BNEF WoodMac Source: Stem. Definition Total value of uncontracted, potential hardware and software revenue from total opportunities currently in process by Stem direct salesforce and channel partners (see page 15) • Market participation revenue is excluded from pipeline Total value of executed customer agreements, as measured during a given period (e.g. quarterly booking or annual booking) Customer contracts are typically executed 6-12 months ahead of installation Booking amount typically includes: ● ● Total value of bookings, as reflected on a specific date Backlog increases as new contracts are executed (bookings) Backlog decreases as integrated storage systems are delivered and recognized as revenue ● ● 1) Hardware revenue, which is typically recognized at delivery of system to customer, 2) Software revenue, which represents total nominal software contract value recognized ratably over the contract period, 3) Market participation revenue is excluded from booking value Segment of market focused on customer-sited installations of energy storage systems (see page 20). Stem excludes residential market when evaluating expected market share in this segment Segment of market focused on independent power producers, renewable project developers and utility / grid operator customers with installations of energy storage systems interconnected to distribution or transmission networks or in connection with a generation asset (see page 20) Confidential 40 Payment for initial purchase of system, which is typically recognized at delivery of system to customer • Total Hardware Revenues = Total Deliveries (kWh) x Project Hardware ASP ($/kWh) • ASP / margin based on value added services including hardware selection, project design and interconnection / permitting advisory and warranty design and compliance Recurring SaaS payment driven by storage assets under management (AUM) Total Software (Recurring) Revenues = Total AUM (kWh) x Software subscription ($/kWh/month) SaaS contracts range 10-20 years comprising recurring monthly payments • Revenues from monetization of energy storage capacity into energy markets and VPPs secured by contracts 3-20 years • Total Software (Variable) Revenues = Total AUM (kWh) x Stem's Market Participation Revenues ($/kWh) Bloomberg New Energy Finance Wood Mackenzie#41stem Market Leader and Continued Growth With Asset Owners and Utilities Stem has a proven track record of helping owners maximize the value of their assets, driving higher revenue and ROI Overview of Front of the Meter Market Utilities, IPPs and other asset owners Typically 20 year software contracts ✓ System spec size of 27MWh and $10MM Wholesale market participation ✓ ✓ Source: EEI, Wood Mackenzie. FTM US Energy Storage Outlook (MWh) 30,000 25,000 20,000 15,000 10,000 5,000 0 2,381 2020 ■ All Others 9,679 2021 ■ California 14,107 2022 49% CAGR 17,107 2023 17,219 2024 Confidential 41 ▪ Arizona ■ Hawaii - New York ■ Massachusetts 21,006 H 2025 26,533 2026 ■ PJM (excl. NJ) ■ Texas#42stem Dominant Market Share with Commercial & Industrial Customers Stem delivers lower net bill and clean power to C&I customers Overview of Behind the Meter Market Commercial, industrial and corporate customers ✓ Typically 10 year software contracts ✓ System spec size of 2.2MWh and $1MM Wholesale market participation V Source: EEI, Wood Mackenzie. BTM US Energy Storage Outlook (MWh) 3,500 3,000 2,500 2,000 1,500 1,000 500 0 292 2020 593 2021 1,336 2022 48% CAGR 1,252 2023 ■ California - New York All Others ■ Massachusetts 1,761 2024 ■ PJM (excl. NJ) Confidential 42 2,238 2025 ▪ Arizona 3,043 2026 ▪ Hawaii ■ Texas#43stem Growing Global Total Addressable Market Transaction capital will fuel growth into international markets with expanding TAM Overview of International TAM System cost declines and demand for renewable energy have led to increasing system durations and MWh capacities ✓ 254 GW of capacity expected to be deployed around the world over the next decade APAC expected to drive 70% of global demand growth through 2030 ✓ Policy tailwinds spurs growth in EMEARC markets Source: EEI, Wood Mackenzie. Worldwide Energy Storage Outlook (Ex-US) (MWh) 30,000 25,000 20,000 15,000 10,000 5,000 0 7,881 2020 ■ Australia ■ India ■ United Kingdom 10,611 2021 ■ Canada ■ Italy 13,040 2022 Rest of Americas 22% CAGR 16,979 2023 18,195 ■ China ■ Japan ■ Rest of APAC Confidential 43 Hi! 2024 21,233 2025 26,630 ■ France ■ South Korea ■ Rest of EMEARC 2026 ■ Germany ■ Spain#44stem Global Energy Storage Market to Grow ~25x By 2030 Global energy storage growth remains robust long-term Overview of Global Growth Trends All major global markets forecasted at double digit storage growth rates over the decade US and China lead energy storage growth with respective CAGRs of ~45% and ~41% respectively through 2030 Regulatory environment in Japan spur residential storage market with renewable growth spurring FTM storage to yield ~19% CAGR through 2030 Lack of market rules, policies, and incentives for storage markets stifle growth in Latin America Source: EEI, Wood Mackenzie. (1) Includes all FTM, non-residential and residential storage. Capacity (GWh) Global Energy Storage Outlook (GWh) 200 180 160 140 120 100 80 60 40 20 0 6 5 22 30 2018 2019 2020 2021 2022 United States EMEA Cumulative Capacity (1 (1) 31% CAGR 37 2023 40 48 62 China Rest of APAC 79 101 Confidential 44 128 164 2024 2025 2026 2027 2028 2029 2030 Japan Rest of World T 800 700 600 500 400 300 200 100 0 Cumulative Capacity (GWh)#45stem GAAP Income Statement ($000s) Revenue Cost of Revenue Gross Margin Operating expenses Sales and marketing Research and development General and administrative Total operating expenses Operating loss Interest expense, net Change in fair value of warrants and emdedded derivative Other expenses, net Loss before income taxes Income tax expense Net Loss Other comprehensive income: Foreign currency translation adjustment Comprehensive Loss Source: Stem financials. Confidential 45 Year Ended December 31, 2019 $ 17,282 20,464 (3,182) 17,462 14,703 10,725 42,890 (46,072) (17,094) 101 (2,203) $(65,268) 6 $(65,274) 54 $(65,220)#46stem GAAP Balance Sheet ($000s) Assets Current assets: Cash and cash equivalents Accounts receivable, net Prepaid expenses Inventory Due from related parties Other current assets Total current assets Property and equipment, net Energy storage systems, net Contract origination costs, net Goodwill, net Intangible assets, net Right-of-use assets Other assets Total Assets Source: Stem financials. Confidential 46 Year Ended December 31, 2019 $ 12,889 6,619 868 6,426 483 6,061 33,346 71 127,428 8,608 1,695 10,694 947 5,664 $ 188,454#47stem GAAP Balance Sheet (Cont'd) ($000s) Liabilities and Total Equity Current liabilities: Accounts payable Accrued liabilities Accured payroll Notes payable - short term Convertible promissory notes Financing obligation - short term Deferred Revenue, current Other current liabilities Total current liabilities Deferred revenue Asset retirement obligation Notes payable Financing obligation Warrant liabilities Lease liability Total liabilities Convertible Preferred Stock, $0.00001 par value; 321,351,021 shares authorized as of December 31, 2019; 191,142,894 shares issued and outstanding as of December 31, 2019 Total Equity: Common stock, $0.000001 par value, 386,728,323 shares authorized as of December 31, 2019; 9,392,682 shares issued and outstanding as of December 31, 2019 Additional paid-in capital Accumulated other comprehensive income Accumulated deficit Total equity Total Liabilities and Total Equity Source: Stem financials. Confidential 47 Year Ended December 31, 2019 $ 12,691 7,307 5,573 28,895 35,690 6,373 11,005 2,636 110,170 9,996 5,759 6,568 74,640 6,276 390 213,799 247,390 0 3,024 54 (275,813) (272,735) $ 188,454#48stem GAAP Cash Flow Statement ($000s) Cash flows from operating activities: Net loss Adjustments to reconcile net loss to net cash Changes in operating assets and liabilities Net cash used in operating activities Cash flows from investing activities: Net cash used in investing activities Cash flows from financing activities: Net cash provided by financing activities Effect of exchange rate changes on cash and cash equivalents Net increase (decrease) in cash and cash equivalents Cash and cash equivalents - beginning of year Cash and cash equivalents - end of year Source: Stem financials. Confidential 48 Year Ended December 31, 2019 $(65,274) 28,667 14,808 $(21,799) $(54,237) $ 67,201 (170) (9,005) $ 21,894 $ 12,889