If 22 percent doesn't sound particularly great, you may be thinking of the (extremely expensive) panels used by NASA in space, which have nearly double that efficiency. However, the slight improvements made by SolarCity with its new panels will still have a big impact, bringing more power, less waste and a smaller footprint to consumers. The company said that a smaller pilot line is already producing the panels, which it will sell in select areas to start with. Once the main line is running, SolarCity will build enough of them to equip up to 200,000 homes per year.