Solar and energy efficiency installation company PosiGen has followed $49m of financing from Goldman Sachs with a $20m round backed by Exelon.

US-based solar and energy efficiency services provider PosiGen has raised $20m from investors including Constellation Technology Ventures, the corporate venturing subsidiary of energy company Exelon.

Constellation was joined in the round by private equity firm NewWorld Capital Group. PosiGen announced the round through a press release, while the figure was disclosed in a securities filing.

Founded in 2011, PosiGen offers residential solar and energy efficiency installations that can be purchased or leased by low-to-moderate income households.

The company is currently…