Dishing Out Real Power “The dish, made by Stirling Energy Systems in Phoenix, is the world’s most efficient solar generator. It uses an old principle—that concentrated light is a great heat source—to achieve a level of efficiency on par with conventional power sources and far higher than traditional solar cells. Instead of converting sunlight directly into electricity, as those familiar rooftop solar panels do, it uses a concave array of mirrors to focus light on a central point, where the resulting heat causes compressed hydrogen to expand, driving a four-cylinder engine that turns a 25-kilowatt generator.”