Ohio State University researchers say they've invented the first rechargeable solar battery. Researchers say it could make solar energy more affordable and open the door for its widespread use as a sustainable power source. The rechargeable battery would lower the cost of storing and using energy. Researchers say the battery should cut the cost of manufacturing solar-energy systems by 25 percent. And the solar batteries should last about the same as rechargeable batteries already on the market. The research team is reporting its findings today in the journal "Nature Communications."