Growth capital for the
energy transition

Sunfox Capital partners with entrepreneurs to build projects and
scale businesses in the emerging renewable energy economy.

About Us

Sunfox Capital is a renewable energy-focused private equity firm

Sunfox Capital invests in the management teams building the new business models required to accelerate the energy transition.

We rely on a relationship-driven, evidence-based approach to investing and work closely with management teams to help them realize their visions. For early-stage companies, we help founders scale their businesses and build support for their strategy with rigorous, fact-based analysis.  For operating businesses, we help identify areas to improve operationally, strategically and financially.

We are creative problem-solvers and structure deals to create win-win scenarios for the entrepreneurs we partner with and our investors.

Where We Invest

Our energy system is transforming.  Technology improvements and rapid cost declines are driving exponential growth in wind, solar, and battery installations.

At the same time, transport, industry, and the built environment are electrifying – placing new demands on the grid. Sunfox Capital will invest in the solutions needed to address these disruptions in the historical patterns of energy generation and consumption.  This focuses our investing activity across a broad spectrum of business types – from project developers to service providers, equipment manufacturers to technology solutions – with the common theme being their contribution to the energy transition.

Ultimately, this line of thinking has led us to concentrate on the four verticals listed below.

Investment Criteria

Growth stage

The growth-stage companies we’re targeting have demonstrated meaningful evidence of commercial traction – so the core business challenge is scaling sales and operations. Importantly, these businesses rely on proven technologies without binary technical risk.

Defensible margins

We target business models that are positioned to generate sustainable margins in the long-run.  These businesses sit in structurally advantaged segments of the value chain and are insulated from competition.

Clear path to profitability

The companies we’d like to work with are still emerging as the new energy landscape unfolds.  Although they may not be cash flowing at this time, their growth prospects provide a clear pathway to profitability.

Strong management teams

Our portfolio companies’ management teams have a demonstrated track record of success, deep sector-specific expertise, and a penchant for using evidence-based analyses to inform strategic decisions.

Portfolio Companies

GridX helps leading utilities to design and implement new rates, quickly operationalize new offerings in their billing and settlement processes, and better engage with their customers for broader program adoption.

Smart Wires designs, manufactures, and sells highly advantaged modular power flow control solutions that allow utilities to push and pull power on their high voltage transmission systems via the injection of electrical line reactance.

Proterra is a leader in the design and manufacture of zero-emission electric transit vehicles and EV technology solutions for commercial applications. Their products include electric powertrain technology for heavy-duty vehicles, electric transit buses, charging infrastructure, and fleet planning.


Brett Annunziato, CFA


Brett has spent over a decade in energy-focused private equity and participated in a wide range of activities – from the sourcing, due diligence, and structuring of new investments to generating solutions for portfolio companies. At Sunfox, he guides the strategic direction of the firm, builds partnerships in support of its priorities, and manages Sunfox’s investment programs. Brett holds a BA in Economics from the University of Colorado and an MBA from the University of Virginia.  He is also a CFA Charterholder.

Marie Conrad


Marie has 15 years of experience in the energy industry working for a major, multinational corporation. Marie has experience managing multi-million dollar business portfolios and leading complex projects. She also is a talented business developer, having launched new businesses, exceeding projected sales volumes, and delivering rapid growth. Marie holds a BS in Chemical Engineering from the University of Texas at Austin and an MBA from New York University’s Stern School of Business.

James Schulte


James spent the last decade building his network and expertise in power, utilities, and the energy transition. Through roles in principal investing, scaling businesses, and strategy, James has developed the knowledge and perspective needed to identify opportunities, diligence them, and pull in advisors and deal partners to help our portfolio companies succeed. James graduated from Yale University with a BA in History Cum Laude and received his JD/MBA from the University of Chicago, both with High Honors.

Contact Us

Sunfox Capital
448 N LaSalle, 9th Floor
Chicago, IL 60654