The Solar Impulse
The Solar Impluse, a project undertaken by the École Polytechnique Fédérale de Lausanne and headed up by the aptly named Bertrand Piccard is a solar powered aircraft capable of both day and night flight thanks to a 450kg Lithium-polymer battery system and 2,200 sq ft of solar panels mounted atop the wings. It has a seating capacity of one, the pilot, and is capable of cruising at 43 mph for 36 hours at a maximum height of 28,000 ft. Bertrand Piccard is the same guy who flew the first ever round-the-world trip in a balloon, much to the dismay of Richard Branson.
The Solar Impulse has 4 10hp electric motors, 2 mounted under each wing, and produces an average of 8hp in total power over the course of a 36 hour flight, interestingly this is almost the same as the infamous Wright Flyer from 1903. Another, much more capable solar plane called the Solar Impulse II is planned for 2011 which would feature a pressurised cockpit allowing it to fly up to 39,000 ft and would be capable of circumnavigating the globe over a period of about 20 days.
Via Solar Impulse