The Guinness record requires the use of solar cells in general, whether they're GaAs or Si cells.

You'd be surprise how much that tag applies to this car.

The available power that the wheel motor can use to accelerate is limited to what the array generated when the battery is removed. During the race, the car has both the power from the array and the battery.

Nuna 5 used 6 sq. meters of Gallium Arsenide cells, which are about 10x more expensive than Silicon cells, which Sunswift IV used. In the upcoming 2011 WSC, GaAs cars are limited to only 3 sq. meters of array surface area.

You wouldn't take a Formula 1 car to the supermarket either.