Last week Solar Impulse flew their prototype plane through the night for the first time. The trip lasted over 26 hours, gathering and storing energy during the day. With 12% efficiency and rationing energy to last the night, the plane has eight horse power to run on. That’s about the same as the Wright brothers had in 1903.
It’s the first night flight ever by a solar powered plane, and in 2013 they plan to go round the world in five stages lasting several days at a time. Their goal is a non-stop round the world flight. Before they can do it, they need to improve battery storage to support the weight of two pilots. At the moment it’s a one man show, and round the world in one go would involve some serious sleep deprivation.