Onyx, based in New York City, did not make terms of the transaction public.
"We are excited to further advance our C&I footprint with this broad array of projects," said Onyx chief executive Matt Rosenblum.
The companies expect this to be the first of several closings, although he did not provide further details.
News of the deal came one day after SunEdison confirmed that NRG Energy won an auction to acquire 2.13GW of its utility-scale solar and wind assets in the US.
SunEdison, the once high-flying renewable energy developer that filed for Chapter 11 bankruptcy protection in April mired in debt, has been selling assets while they retain some value to partially repay creditors.
The US Bankruptcy Court for the Southern District of New York has been overseeing this process.
Onyx was created in October 2014 by funds managed by Blackstone, the world’s third largest private equity firm. It focuses on greenfield development in the North American solar and wind sectors.
