Activists protesting cuts in subsidies to solar power in Germany protest outside the building where Vice Chancellor and Economy Minister Philipp Roesler and Environment Minister Norbert Roettgen were announcing the cuts on February 23, 2012 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Workers prepare the roof of a house to get installed solar power modules for producing heat on October 15, 2011 in Wessling, Germany. Germany has and is continuing to invest heavily in solar energy, both in the public and private sectors. The German government introduced a feed-in tariff with its Renewable Energy Act in 2000 that guarantees homeowners a minimum rate for selling electricity from renewable energy sources into the nation's electricity grid. (Photo by Alexandra Beier/Getty Images)

“NASA's Pathfinder, Pathfinder Plus, Centurion and Helios Prototype were an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as “atmospheric satellites”, to perform atmospheric research tasks as well as serve as communications platforms”. – Wikipedia

Photo: The solar-electric Helios Prototype flying wing is flies over the Hawaiian islands of Niihau and Lehua during the first solar-powered test flight July 14, 2001 from the U.S. Navy's Pacific Missile Range Facility on Kauai, HI. The 18-hour flight was a functional checkout of the aircraft's systems and performance in preparation for an attempt to reach sustained flight at 100,000 feet altitude later in the summer. (Photo Courtesy of NASA/Getty Images)

Jason Arnold, project manager from solarcentury walks between lines of solar panels erected at Weighbridge, Wheal Jane, Baldhu on July 7, 2011 near Truro, England. A ceremony was held today to mark the connection of the 1.4kw solar farm, which on a 6.2 acre plot is the first in the South West and biggest in the UK to date, using 5,680 panels. (Photo by Matt Cardy/Getty Images)

A visiter is attracted by the chairs covered with solar panels at the factory of Yingli Green Energy Holding Company, also known as Yingli Solar, on June 20, 2011 in Baoding city of Hebei Province, China. According to a report by the International Energy Agency (IEA), China overtook America as the world' s largest energy consumer in 2010. New energy industries are becoming even more important than in the past. (Photo by Feng Li/Getty Images)

“Solar Impulse is a European long-range solar powered plane project being undertaken by Bertrand Piccard and André Borschberg. The project eventually hopes to succeed in the first circling of the earth with a piloted fixed-wing aircraft using only solar power. 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”. – Wikipedia


Photo: Workers prepare the Solar Impulse airplane HB-SIA for a first runway test on November 19, 2009 in Dubendorf, Switzerland. Solar Impulse chairman Bertrand Piccard, psychatrist and aeronaut, who made the first non-stop round-the-world balloon flight, and CEO and former fighter pilot Andrй Borschberg plan a round-the-world flight, driven only by solar energy, for 2012. (Photo by Johannes Simon/Getty Images)