WindSail Capital Group is a Boston-based investment firm providing growth capital to companies advancing energy innovation, climate tech, and sustainability. The firm specializes in flexible financing solutions—primarily senior secured loans—that facilitate growth while minimizing dilution.
Their most common stage is growth (57% of deals). Average disclosed round size is $4.2M (across 6 rounds with reported amounts).
Portfolio
7
Fund Size
—
Top Stage
Growth
Last 12 Mo
0
Team
MR
Michael Rand
Co-Founder & Managing Director
IB
Ian Bowles
Managing Director
MT
Matthew T. O'Rourke
Managing Director
Portfolio Breakdown
Stage Distribution
Sector Distribution
Investment Activity
DealsAvg Round Size
Portfolio
7 investments
| Company | Round | Amount | Date |
|---|---|---|---|
| WWeatherFlow-Tempest | Growth | $3M | Dec 2024 |
| WWeatherflow | Growth | $3M | Apr 2023 |
 Velocia | Growth | $2.5M | Aug 2022 |
 Varentec | Series A | $7.7M | Nov 2019 |
| VVarentec | Unknown | $5M | Nov 2019 |
| EEccentex, Inc. | Strategic | — | — |
| DDC Systems | Growth | $4M | — |
Top Co-Investors
Last updated: 14 September 2026