WindSail Capital provides flexible financing solutions to companies advancing energy innovation, climate tech and sustainability — accelerating growth without unnecessary dilution.
WindSail Capital is a leading provider of growth capital to companies advancing energy innovation, climate tech and sustainability across a wide range of industries.
Our unique investment approach provides companies with flexible financing solutions that facilitate growth while minimizing dilution — filling a critical gap in the market for mission-driven businesses.
Learn More About Our Approach →We combine deep sector expertise and a 15+ year track record with creative capital structures to unlock growth for businesses that seek alternative sources of financing.
Decades of relationships and experience across clean energy, sustainability, and climate technology sectors.
We are nimble and think creatively — designing bespoke financing solutions that fit each company's unique growth trajectory.
We are there to actively support our portfolio companies beyond capital — providing guidance, introductions, and strategic counsel.
We provide capital to market segments that fall between traditional venture equity and institutional lending.
Our experience and funding model allows us to move quickly and creatively for our partner companies.
Founders retain control. Our debt and hybrid structures are designed to fuel growth without sacrificing equity.
Revolve Labs, Inc. operates next-generation data centers focused on Bitcoin mining hosting and AI high-performance computing infrastructure, leveraging proprietary energy optimization technology to deliver industry-leading cost efficiency.
Enelytix, Inc. provides data-driven analytics and forecasting solutions for the rapidly evolving electric power sector worldwide.
Eccentex, Inc. provides digital transformation solutions through its proprietary AI-driven no-code/low-code AppBase platform for enterprise case management and workflow automation.
BetterFleet provides fleet operators with a single platform to plan, manage and accelerate the transition to zero-emission vehicles while reducing cost and risk.
Brightly Ventures creates value at the intersection of food recovery and climate change mitigation. Brightly is the first US-based company minting verified carbon credits addressing local food recovery and waste diversion.
STAFL Systems is an engineering firm based in San Francisco, CA that specializes in the design and manufacturing of custom powertrain solutions integrating energy storage systems for demanding performance specifications with large OEMs in the marine, industrial, aerospace, mining and automotive sectors.
WeatherFlow-Tempest is a technology company based in Santa Cruz, CA providing proprietary weather stations and associated services to deliver accurate and precise local weather information to businesses and consumers.
Axiom Cloud is an IoT software-as-a-service company based in Oakland, CA that focuses on grocery stores and other owners of cold storage assets to reduce energy and maintenance costs, service calls and refrigerant leak rates.
The acquisition expands Yes Energy's investment-grade forecasting and analytics capabilities for power market participants.
Read More →Our team combines deep energy sector expertise with decades of investment experience. We bring more than capital — we bring relationships, operational insight, and a shared commitment to a sustainable economy.
WindSail Capital Group is a leading provider of growth capital to companies advancing energy innovation and sustainability. Since founding, we've backed 40+ companies across the clean energy economy.
WindSail provides growth capital to companies advancing energy innovation, climate tech, and sustainability. We invest in a wide range of businesses — software, services, tech-enabled models, light manufacturing, transportation, agriculture, and more. Our investments typically range from $2 million to $5 million in the form of a senior secured loan.
We define sustainability broadly. Our portfolio spans software, services, tech-enabled businesses, light manufacturing and hardware, transportation and logistics, agriculture, solar and battery materials, and wastewater treatment — the common thread is that every company is doing something meaningful for energy transition or environmental impact.
Our investment approach allows us to focus on early stage companies that are often overlooked by institutional investors, such as We do not require an active equity round — our capital can stand alone whether you have institutional backing, are between rounds, or are founder-backed. We also work well alongside equity investors and often complement a round.
We understand the energy industry and its complex ecosystem. We think creatively to structure well-balanced transactions that enable growth — serving companies often overlooked by institutional investors.
WindSail Capital has been investing across the energy, climate tech, and sustainability economy for over 14 years.
The energy sector is dynamic. We build flexibility into every transaction — rigid lending doesn't serve innovative companies.
Over a decade investing exclusively in energy and climate tech gives us depth that makes us better partners and underwriters.
Less dilutive capital, deployed thoughtfully, is one of the most powerful tools available to climate tech founders.
Whether you're a founder exploring financing or an LP evaluating the fund, we'd welcome a conversation.
A small, focused team with deep roots in energy policy, structured lending, and climate technology — united by a common mission.
Ian is co-founder and Managing Director of WindSail Capital Group. He brings over 30 years of experience in the energy and environmental sectors. Prior to WindSail, he served as Massachusetts Secretary of Energy and Environmental Affairs, where he oversaw a landmark restructuring of utility and environmental regulation which included making MA a top ranked state in energy efficiency, renewable energy and greenhouse gas emissions reductions. He was also chairman of the MA Water Resources Authority and the founding chairman of the MA Clean Energy Center. Earlier in his career, he served on the National Security Council staff of President Bill Clinton and was a Vice President at Conservation International where he played a key role in creation of the four million acre Central Suriname Nature Reserve.
Ian is a board member at Longroad Energy and formerly a board member at the New England Clean Energy Council and the Museum of Science. He is an advisor to several other leading clean energy companies. Ian received his A.B. from Harvard College and a Masters degree from Oxford University.
Michael is co-founder and Managing Director of WindSail Capital Group. Michael brings to WindSail over 25 years of experience in private equity investing, structured finance and corporate finance. Prior to founding WindSail, Michael spent 11 years as a private equity professional, most recently as a Managing Director of GB Merchant Partners, a division of Gordon Brothers Group. Previously, Michael served as a Principal at Palladin Capital Group, a New York based middle market private equity firm. Prior to joining Palladin, Michael was a member of the Leveraged Finance/Merchant Banking Division of CIBC World Markets.
Michael received a B.S. from Georgetown University and an MBA from New York University’s Stern School of Business. He currently serves as the Chairman of Coaching4Change.
Matt joined the WindSail team in 2015. Matt has over 16 years of broad industry experience as an investor and lender and has directly managed over $500 million in assets. Prior to joining WindSail, Matt was a Vice President, Senior Portfolio Manager and founding team member at Salus Capital Partners, a $1.4-billion credit fund. At Salus, Matt was responsible for underwriting, structuring and managing a diverse portfolio of credit facilities to lower middle market businesses across North America. Prior to joining Salus Capital, Matt was an Assistant Vice President at M&T Bank (formerly People's United Bank) where he sourced, underwrote and managed a portfolio of middle market commercial loans. Matt began his career at M&T Bank as a credit analyst where he underwent an eighteen-month credit training and rotational program within the bank.
Matt received a B.S. in Business Administration cum laude from Bryant University.
Andrew is a Vice President who joined the WindSail team in January 2021. At WindSail, he helps lead deal sourcing, pipeline development, and investment due diligence across the fund — working closely with the investment team from initial company evaluation through term sheet negotiation and portfolio monitoring.
Andrew also serves as an advisor to the Cleantech Open Northeast, supporting the next generation of early-stage climate tech founders. Prior to WindSail, Andrew worked as an Associate in M&A advisory with King & Spalding and in investment banking with Wells Fargo Securities. He received a B.A. in Economics and Mathematics from Amherst College and is based in Boston, MA.
We're always open to connecting with exceptional founders, investors, and professionals in the energy and climate space.
WindSail has backed 40+ companies across energy and climate tech since 2013 — providing non-dilutive growth capital to founders building the energy transition.
Current investments — each a growth-stage business receiving a senior secured loan from WindSail.
Revolve Labs, Inc. operates next-generation data centers focused on Bitcoin mining hosting and AI high-performance computing infrastructure, leveraging proprietary energy optimization technology to deliver industry-leading cost efficiency.
Enelytix, Inc. provides data-driven analytics and forecasting solutions for the rapidly evolving electric power sector worldwide.
Eccentex, Inc. provides digital transformation solutions through its proprietary AI-driven no-code/low-code AppBase platform for enterprise case management and workflow automation.
BetterFleet provides fleet operators with a single platform to plan, manage and accelerate the transition to zero-emission vehicles while reducing cost and risk.
Brightly Ventures creates value at the intersection of food recovery and climate change mitigation. Brightly is the first US-based company minting verified carbon credits addressing local food recovery and waste diversion.
STAFL Systems is an engineering firm based in San Francisco, CA that specializes in the design and manufacturing of custom powertrain solutions integrating energy storage systems for demanding performance specifications with large OEMs in the marine, industrial, aerospace, mining and automotive sectors.
WeatherFlow-Tempest is a technology company based in Santa Cruz, CA providing proprietary weather stations and associated services to deliver accurate and precise local weather information to businesses and consumers.
Axiom Cloud is an IoT software-as-a-service company based in Oakland, CA that focuses on grocery stores and other owners of cold storage assets to reduce energy and maintenance costs, service calls and refrigerant leak rates.
Prior investments — many with significant exits and acquisitions.
We're always evaluating new opportunities. If you're a growth-stage clean energy company seeking non-dilutive capital, we'd like to learn more.
Announcements, milestones, and press from our portfolio companies and the WindSail team.
Whether you're a climate tech founder, potential LP, or fellow investor in the ecosystem, we'd love to hear from you.
133 Federal Street, Suite 902
Boston, MA 02110
info@windsailcapital.com
We invest $2–5M in senior secured loans to growth-stage clean energy companies across energy storage, grid technology, clean mobility, and environmental services.
Tell Us About Your Company →WindSail Capital is currently deploying capital. If you're a family office, institutional investor, or individual LP, we're happy to share materials.
Request nformation →We're always looking to expand relationships with entrepreneurs, advisors, co-investors, and cleantech community organizations.
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