Microsoft Founder Bill Gates is backing a solar cell maker that can produce more energy than conventional solar cells. Gates' Breakthrough Energy Ventures has money on Massachusetts-based CubicPV, which makes photovoltaic cells using perovskite -- a composite that produces at least 20% more energy than the prevailing silicon technology.

The perovskite material must still prove its durability. But if this can happen, the technology could cause solar's market share to skyrocket, which will comprise 54% of all electricity added to the grid in 2023, according to the U.S. Energy Information Administration.

"The sun never raises its price and it doesn't have blackouts," says Chris Case, chief technology officer for the UK-based Oxford PV. "It's the ideal energy source."