A huge plane powered by solar energy is being tested in Switzerland. In December, the airplane made its first successful test flight, rising at a height of just one meter above the ground.
This year, it is expected to fly for about 36 hours – the first ever night flights by an airplane powered only by solar cells.
Its dimensions are enormous, having 21.85 meters long and 6.4 meters high and is almost as wide as a Boeing 747 or Airbus A340. Unlike a Boeing 747, which has a maximum takeoff weight of over 333 tons, the HB-SIA tips the scales at only 1.6 ton.
The 11,628 photovoltaic (PV) cells (giving a coverage of 200 square meters) are mounted on the wings and horizontal tail area. They are able to generate electricity for the four electric engines. The cells have a conversion efficiency of 22% and are 150 micrometers thick. The average flight speed of the HB-SIA is only 70 kilometers per hour and the average output of the engines is 6 kW.
While flying during the night, the electricity produced by the solar cells by day is stored in a series of lithium polymer rechargeable batteries, weighing a total of 0.4 tons.
