Mattern

Sara Mattern

Partner
Co-Chair, Emerging Company & Venture Capital Practice Group
Washington, DC, Boston

At Foley Hoag, we are focused on the mission of fighting climate change through innovation and collaboration.

Sara Mattern guides emerging companies, investors and sustainable infrastructure project developers on financings and strategic development. She works with clients in the climate, sustainability, bluetech, life sciences and technology sectors on innovative technologies and business approaches to solving our most pressing challenges.

Sara acts as general outside counsel to emerging companies on all aspects of their business, including early-stage formation and structuring matters, venture financings, strategic alliances and acquisitions. Sara also works with incubators and accelerators to support the development of their member companies.

Sara is a leader in the firm’s Energy Project Finance and Development practice. She advises sponsors and investors on all aspects of renewable energy project development, tax equity transactions, sponsor equity investments, debt financings, acquisitions, federal tax credits and state incentives, with a particular focus on solar and storage projects.  Sara works with renewable energy developers and investors to navigate tax equity transactions, including structuring, tax credit transfers, qualification for tax credits, and compliance with Inflation Reduction Act requirements.

Sara has been recognized externally by the Venture Capital Journal as One of Venture Capital’s 40 Rising Stars and as One to Watch for Energy and Venture Capital law by Best Lawyers in America.

Education

  • Boston College Law School, J.D., cum laude
  • Georgetown University, B.S.F.S., cum laude

Bar and Court Admissions

BAR ADMISSIONS
  • District of Columbia
  • Massachusetts

Languages

  • Spanish

Experience

RENEWABLE ENERGY PROJECT FINANCE
  • Impact investing firm Monarch Private Capital in the tax equity financing of a 190 MW solar project developed by Sol Systems, a national renewable energy company, to advance sustainable energy and contribute to the development of clean energy infrastructure in southern Illinois
  • Leading independent power producer Soltage, LLC in a $250 million partnership with investment management firm Harrison Street to fund solar and other clean energy infrastructure assets developed by Soltage 
  • Spring Lane Capital in investments in distributed waste water and composting infrastructure investments 
  • AEGON USA Realty Advisors (an affiliate of Transamerica) in connection with tax equity investments in North Carolina solar portfolios totaling 100MW and 30MW, respectively
  • A sponsor equity investor in its investment in a portfolio of over 30MW of wind and solar PV
  • Solar developers and investment managers in multiple acquisitions of solar project portfolios
  • Soltage, LLC in connection with a $140 million equity capital partnership with Basalt Infrastructure Partners LLP and various joint ventures, project acquisitions, tax equity and back leverage financings, and other financing transactions
  • Greenwood Energy, a division of a diversified family-owned business, in US solar financing activities, including hybrid construction and permanent lending facilities, tax equity financings and back leverage lending facilities
  • GoldenSet Capital Partners in connection with $50 million sponsor equity and tax equity investments for a portfolio of Massachusetts solar projects
  • Advise sponsors and developers in back leverage debt financings of solar assets
VENTURE FINANCINGS
  • Engine Ventures, as lead investor in a $60 million Series A investment in DG Matrix, a cleantech startup developing a multi-port solid-state transformer platform for datacenters and distributed energy.
  • Zero Homes, a technology company pioneering an end-to-end digital platform that removes friction from home upgrades for both homeowners and contractors, in its Series A raise led by Prelude Ventures and including SJF Ventures, Exelon Foundation, and existing investors VoLo Earth Ventures, Overture VC, and FJ Labs
  • Renatural, Inc., in a $4.2M Seed round led by Watchfire Ventures, with participation from Mark Cuban and Ingeborg Investments, to grow its proprietary hyper-realistic wig-making business.
  • RenewCO2, Inc., a carbon-negative chemicals and fuels company converting carbon dioxide and water into sustainable chemicals at low cost and high efficiency, in its $4 million Series Seed Financing led by Energy Transition Ventures, with participation from Dai Nippon Printing Co., Ltd.
  • Advised florrent, Inc., an energy technology company providing economical power quality and reliability solutions for a stable and decarbonized grid, in its oversubscribed $9.5M Seed-2 funding round
  • Sightline Climate in its $5.5 million Series Seed financing. Sightline Climate is a leading climate market intelligence platform and runs the popular CTVC newsletter
  • Cyvl.ai, a company specializing in enterprise AI solutions for transportation infrastructure, in its $14 million Series A financing round led by Sentinel Global, with participation from new and existing investors
  • Represent Azolla Ventures in numerous equity investments, enabling catalytic capital to invest in companies with the potential for gigaton-scale carbon dioxide equivalent reductions
  • NODAR Inc., a maker of 3D vision software for autonomous vehicles, in a $12 million Series A financing lead by NEA, and its previous in $2.7 million Series Seed Financing 
  • Modern Hydrogen, Inc., a sustainable heat and power startup, in $30 million Series B financing 
  • Energetic Insurance, a Managing General Underwriter, in a $7 million Series A financing led by Schneider Electric Ventures, with participation from MS&AD Ventures, Atlantic Global Risk, and MCJ Collective 
  • Kula Bio, Inc. in $50 million Series A financing
  • Prime Impact Fund as lead investor in multiple climate-tech companies
  • MyA Health, Inc. in equity financing led by Pillar VC
  • KnipBio, Inc. in venture financings and strategic collaborations
  • Vergent Bioscience, Inc. in $11 million Series A financing
  • Tank Utility, Inc. in multiple equity financings
  • Recorded Future, Inc. in multiple venture financings, including $25 million Series E round
  • A leading residential energy efficiency provider in multiple equity financings
  • Altaeros Energies, Inc. in a Series A financing led by Softbank Corp.
MERGERS & ACQUISITIONS
  • Enelytix, Inc., a leading provider of cloud-native power market modeling and a comprehensive long-term nodal forecasting platform, in its sale to Yes Energy, a leading provider of power market data and software
  • FX HedgePool, a major institutional swap matching service, in a strategic acquisition by LMAX Group, the leading independent operator of institutional execution ventures for FX and digital assets trading
  • Recorded Future, a threat intelligence company, in its sale of a controlling interest in the company valued at $780 million to Insight Partners
  • Tank Utility, Inc., leading provider of remote monitoring services for truck-delivered energy, in its sale to Generac Power Systems
  • 7AC Technologies, a developer of ultra-high efficiency HVAC systems, in its sale to Emerson Electric
  • Sun Catalytix in sale to Lockheed Martin
  • Alere Inc. in its $600 million sale of Alere Health, LLC to Optum
  • Represented LIFTE H2, a digital asset management platform for managing hydrogen data and assets, in an assets sale to Electric Hydrogen

Other Publications

  • Note, “Municipal Energy Benchmarking Legislation for Commercial Buildings: You Can't Manage What You Don't Measure,” 40 Boston College Environmental Affairs Law Review 487 (2013)
  • Comment, “FYI to the FAA on FLL: Approval of a Runway Extension in City of Dania Beach” 39 Boston College Environmental Affairs Law Review E. Supp. 69 (2012)

Honors & Involvement

HONORS
  • The Legal 500 United States: Next Generation Partner, Venture Capital and Emerging Companies (2025-2026)
  • Best Lawyers: Ones to Watch - Energy Law (2023-2025) and Venture Capital Law (2023-2025)
  • Venture Capital Journal: one of venture capital's 40 rising stars (2021) 
  • Greater Boston Chamber of Commerce: Women’s Leadership Program (2018-2019) 
INVOLVEMENT
  • Greentown Labs, Advisory Board Member
  • SeaAhead, Advisory Board Member
  • MassChallenge, Bluetech Partner
  • Georgetown University, Expert in Residence for Georgetown Entrepreneurship Initiative
  • Women’s Bar Association, Member
  • New England Women in Energy and the Environment, member
  • Foley Hoag Foundation, Grant Proposal Reviewer
  • Cleantech Open, Judge and Mentor
  • Women’s Energy Network, Member, Boston chapter

Events

Houston Climatetech Summit  Page
Sponsorship 09/15/2026
Cocktails>Panels Page
Sponsorship 07/15/2026
Boston Climate Week ClimaTech Page
Sponsorship 05/04/2026
FOAK War Stories Page
Foley Hoag Event 04/01/2026
Industry Growth Forum Page
Sponsorship 03/31/2026
Colorado Climate Week  Page
Sponsorship 03/30/2026
Bagels > Panels Page
Event 03/19/2026
Bagels > Panels Page
Event 02/12/2026
2025 Green Future Gala Page
Sponsorship 10/16/2025
Pitching Your Deal Workshop Session Page
Speaking Engagement 05/15/2025
Energize NEXT: The Climate Software Summit  Page
Speaking Engagement 10/04/2023

Speaking Engagements

  • Speaker,  “Breaking New Ground: Legal and Business Perspectives for FOAK Companies," FOAK Summit (September 2025)
  • Speaker, “Pitching Your Deal Workshop Session,” Novogradac’s 2025 Spring Renewable Energy Tax Credits Conference (May 15, 2025)
  • Panelist, "Trailblazers & Risk-Takers: FOAK Projects Transforming Climate Action," Colorado Climate Week (March 26, 2025)
  • "Hydrogen Growth Potential: Supply, Demand and the Value of Market Data," the Electric Power Research Institute (June 2024)
  • Moderator, "Electrify That: Transitioning from the Petro- to Electro-Economy," EnergizeNEXT Climate Software Summit (October 4, 2023)
  • Panelist, “Valuation: Insights for Success from Investors and Entrepreneurs” ecosVC Tough Ventures series (November 12, 2021) 
  • Speaker, “The Role of an Attorney for Cleantech Startups” Cleantech Open (July 26, 2021)
  • Speaker, “Choice of Entity Considerations,” 2021 BizGrow Conference, Lawyers for Civil Rights (July 22, 2021)  
  • Panelist, “Legal Challenges for a Cleantech Startup,” Cleantech Open Academy (June 4, 2021)  
  • Panelist, “The Future of Sustainability,” Angel Capital Association Fall Forum (October 27, 2020) 
  • Speaker, “Business Formation Considerations for Clean Energy Businesses,” Cleantech Open 2020 (July 30, 2020) 
  • Speaker, “Choice of Entity Considerations,” 2020 BizGrow Conference, Lawyers for Civil Rights (July 16, 2020) 
  • Speaker, “Legal Challenges for a Cleantech Startup,” Cleantech Open East Coast Academy (June 2, 2020) 
  • Moderator, “Development and Financing Trends in the Northeast,” Solar and Energy Storage Northeast Forum (February 19, 2020) 
  • Panelist, “The Future of Electric Vehicles,” Women’s Energy Network, Boston Chapter (November 19, 2019) 
  • Speaker, “Equity Compensation Basics for Startups,”  Greentown Labs (October 30, 2019)
  • Speaker, “Out of the Incubator: Finding Office Space for Startups,” Massachusetts Clean Energy Center and City of Somerville (October 30, 2019)
  • Webinar, "Preparing for Investors: Understanding Term Sheets and Financings" (August 5, 2019) 
  • Speaker, “Legal Challenges for a Cleantech Startup,” Cleantech Open East Coast Academy (June 12, 2018)