Submitted to extreme differences in temperature and heavy gales of up to 250km/h, the solar cells which are to be used on the first test flights of the Solar Impulse prototype in late summer 2009 have passed a challenging test. Since December the cells have been tested in the high alpine research station “Mont-Soleil” on the Jungfraujoch at 3580 metres above sea level to determine the photovoltaic efficiency of the panels. The tests were conducted under extreme atmospheric conditions and heights. They confirm that the cells’ efficiency of more than 22 percent is noticeably higher than that of conventional solar cells. The contacts of the solar panels are assembled solely on the back so that the entire front can be used for energy absorption.

During the planned first manned round-the-world flight of Solar Impulse in 2011, relying solely on the power of the sun, the demand placed on the solar cells is going to be huge: they have to be extremely light, yet at the same time durable and highly efficient, being able to withstand differences in temperature of +80°C to -60°C and changing conditions between altitudes of 1 km to 12 km.