Published on August 26th, 2011 | by Charis Michelsen4
Panasonic’s Solar Cells Take On the World Solar Challenge
August 26th, 2011 by Charis Michelsen
Specialized challenges are usually pretty entertaining – wacky ideas come to life to compete, and often garner some pretty impressive results. The upcoming World Solar Challenge in Australia should deliver some fun; competitors must drive from Darwin to Adelaide, a total of 1,864 miles across the desert, without using any fossil fuel.
Japan’s Tokai University will be competing for the second time, using Panasonic’s HIT (heterojunction with intrinsic thin layer) solar cells. The silicone-based HIT solar cells, which demonstrate a high rate of conversion efficiency, are to be used for the first time in a race car.
Tokai University team director Kimura Hideki, professor of electrical and electronic engineering, praises the HIT cells as being inexpensive and environmentally friendly as well as highly efficient. The team claims 22% conversion efficiency with 1.32kW maximum output. The last time Tokai University participated in the World Solar Challenge, they won with Sharp compound solar cells – highly efficient and used in space satellites. Current regulations have cost them that advantage, but the team remains enthusiastic about the HIT solar cells.
HIT solar cells were originally developed by Panasonic subsidiary Sanyo. They use a hybrid system; both sides of the crystal silicon substrate are coated with an amorphous thin film silicon formation. Since an amorphous formation is used, the HIT solar cells avoid the pitfall of most silicone-based products – a loss of conversion efficiency as temperatures rise.
“The high temperatures were the deciding factor in the choice of HIT,” explained Professor Kimura. “The desert is hot, and the panels can reach temperatures of 80 degrees [Celcius]. The car just stops moving at that rate.”
Of the 42 teams competing this year, five are using Panasonic batteries, including Delft University from the Netherlands and the teams from both Stanford and the University of California. Professor Kimura regards all three teams as strong competitors. However, since only the Tokai team is using HIT, they feel they maintain an advantage.
The batteries provided by Panasonic are Type 18650, the same type used by laptop computers. 15 rows of 30 batteries each means 450 in total – the same formation used by the Tesla Roadster. The lithium ion batteries use a nickel-based material for their electrodes, which has a higher capacity when compared to manganese or cobalt. Higher capacity leads to higher heat production, though, which Panasonic has addressed with their proprietary heat-resistant layer.
Panasonic’s involvement in the race will also provide them with valuable data on the performance of their new products, which they plan to use in devising sales and marketing plans. When combined with the publicity involved in helping sponsor the race, it seems like a pretty good deal for Panasonic.
Other sponsors for the Tokai team include Mitsuba (providing the engine’s major electrical components) and Toray (carbon fiber for the body).