An anonymous reader writes: Alta Devices, a startup funded by Bill Joy among others, has recently announced a record-breaking gallium arsenide solar cell with 28.2% efficiency, roughly double that of conventional silicon devices. That's not news, more complex GaAs cells up to 42% have been around for a while. The real breakthrough here is that the cell is a lightweight, robust and flexible material only 1 micrometer thick — only a tiny bit of GaAs is needed. If their production line works out, the cells will cost the same as the lowest cost thin-film cells available today, but with about three times the performance, or more. This makes grid parity a possibility, and these cells a seriously disruptive technology.