Remember those times you actually needed a roof on your house to capture the sun’s energy? No more. Windows are the next frontier. Researchers from Michigan State University have designed a new type of solar concentrator that can be put over clear windows to turn them into solar cells. The efficiency of the solar concentrator is less that half of conventional panels. But what it lacks in efficiency today, it more than makes up for in usability tomorrow—think of how much energy could be produced if every window was a solar panel!