Solar Impulse is an European long-range solar powered plane project being undertaken at the École Polytechnique Fédérale de Lausanne. The project eventually hopes to succeed in the first circling of the earth with a piloted fixed-wing aircraft using only solar power. The project is promoted by Bertrand Piccard, who co-piloted the first balloon to circle the world non-stop.

The first aircraft, bearing the Swiss aircraft registration code of HB-SIA, is a single-seater, capable of taking off under its own power, and intended to remain airborne up to 36 hours. This aircraft first flew an entire diurnal solar cycle, including nearly 9 hours of night flying, in a 26-hour flight on 7-8 July 2010. Building on the experience of this prototype, a slightly larger follow-on design (HB-SIB) is planned to make circumnavigation of the globe in 20-25 days.