2012 Ford Focus

Many houses, stores, and factories across the U.S. now have arrays of photovoltaic solar cells mounted on their roofs. These days, that's hardly news. But Ford's announcement that it will install half a megawatt of power-generating solar panels at its Wayne, Michigan, assembly plant has a new angle: The plant will also store some of that solar energy in lithium-ion batteries, letting Ford draw on it even after dark. Pairing lithium-ion storage batteries--which use large arrays of the same lithium-ion cells that power future plug-in hybrid and electric cars--is seen by utilities as a way to...