Enter Nanosolar, a San Jose-based start-up that manufactures thin-film solar panels. Unlike the bulky silicon panels that dominate the solar market, Nanosolar thin-film technology is light and extremely cheap to make. The key is the manufacturing process: while silicon panels need to be baked in batches, Nanosolar’s thin-film panels roll off the assembly line, as if from a printing press. (via TIME’s Best Inventions of 2008)