With a tentative agreement to be purchased by its sister company, Tesla Motors, SolarCity is going all in on a strategy that some analysts say is ahead of its time: pairing solar systems with the automaker's energy-storage batteries.
The success of large-scale solar has raised questions about the wisdom of continuing incentives for rooftop installations, which remain far more expensive than most other forms of electricity.
The announcement marks the largest funding to date for Mosaic, which in the last two years has grown into the nation's top loan provider for residential solar installations.