For the next 8.5 hours, the cars wheeled around the track, where race officials imposed a 65-mph speed limit. Then they re-charged until 9 p.m., at which point the cars' batteries were impounded to ensure the teams were not covertly powering their batteries with anything other than sunshine. On a really sunny day, McKeegan said the Solar Phantom could maintain 72 mph for as much as 4 hours on a flat road. If it's sunny, you can re-charge in four to five hours. If it was overcast it would take the whole day.
Speed is controlled by a switch on the car's steering wheel.
Acceleration on solar cars consumes a lot of sun power. For those reasons and many others, don't expect to see the Phantom or others of its ilk on the market any time soon. Solar cars are not practical today. With a solar car this just is not going to happen. Another problem is the durability of the car.