The solar car "Tokai Challenger"
The solar car "Tokai Challenger"
[Click to enlarge image]
The car being test-driven on the university campus
The car being test-driven on the university campus
[Click to enlarge image]

Tokai University disclosed its solar car to run in the solar car race "Global Green Challenge," which will take place from Oct 24 to 31, 2009, in Australia.

After the press conference, Kenjiro Shinozuka, one of the drivers of the solar car, "Tokai Challenger," test-drove it on the university campus.

The solar car is equipped with triple-junction compound solar cells that use indium gallium phosphide (InGaP), indium gallium arsenide (InGaAs) and germanium (Ge) for top, middle and bottom cells, respectively. They are originally space cells and feature a cell conversion efficiency of 30%.

A total of 2,176 cells, each of which measures 77 x 39mm, were installed on the top surface of the vehicle. When used as space cells, they are sealed with glass to make a module. This time, however, the cells are sealed with a film so that they can be mounted on a curved surface and the total weight of the solar car can be reduced.

The total area of the solar cells is 6m2, and the total output is 1.8kW. Generated electricity drives Mitsuba Corp's brushless DC direct drive motor (efficiency: 97%) after passing through Mishimaki Denshi Y.K.'s buck-boost type maximum-power-point tracking circuit (efficiency: 98%). Also, Panasonic Corp's Li-ion secondary battery (5.6kWh) is used to store electricity.

"By making the most of knowledge to be obtained from the coming race, we would like to expand the application of our solar cells," said Toshishige Hamano, executive vice president of Sharp Corp, which provides its solar cell for the Tokai Challenger. "But we are not planning to use the space cell for normal vehicles."

To use the space cell on earth, it is necessary to develop a substitute for arsenic, which is used for the middle cell, or to establish a recycling system for it, Sharp said.

"This time, our solar cell is recyclable, so we decided to use it on earth as an exception," Hamano said.