Solar energy’s Achilles heal has never been collecting the sun’s rays, but storing energy for those times when the sun is not shining.
However, a few groups think they have moved a step in the right direction to solving that problem: Trapping the heat of the sun, not its electricity potential. It’s called solar thermal heat.
From the New York Times:
Solar thermal systems are built to gather heat from the sun, boil water into steam, spin a turbine and make power, as existing solar thermal power plants do — but not immediately. The heat would be stored for hours or even days, like water behind a dam.
A plant that could store its output could pick the time to sell the production based on expected price, as wheat farmers and cattle ranchers do. Ausra, of Palo Alto, Calif., is making components for plants to which thermal storage could be added, if the cost were justified by higher prices after sunset or for production that could be realistically promised even if the weather forecast was iffy. Ausra uses Fresnel lenses, which have a short focal length but focus light intensely, to heat miles of black-painted pipe with a fluid inside.