The C-Max Solar Energi carries a small, 300 watt solar array on its roof that by itself can't charge the car in a day, even with no clouds and the sun stayed perfectly centered over the car.
Ford says its patent-pending solar-concentrator will solve that problem. About 16 feet long, the concentrator, essentially a carport with a translucent roof, magnifies solar rays to produce 8 kW from the car's small solar panels. But even then, there's a catch: Solar electricity production drops off dramatically if the sun is not directly overhead. Ford leaves it to the car to take care of that.
The carport is designed to be installed in an east-west orientation. So as the sun moves to the west, the car creeps to the east throughout the day. The car starts out sticking out the west end of the carport, and ends up sticking out the east, driving itself more than 30 feet throughout the day to collect maximum solar radiation. From a legal standpoint, that’s the hangup. Would you buy a car that drove itself while you weren’t even there? (To be sure, modern technology allows cars to park nearly autonomously, albeit while you’re sitting behind the wheel with your foot on the brake. So it’s possible for the car to detect obstacles and stop before it hits anything. But this seems like another step out of car owners’ comfort zone.)
Perhaps the most interesting thing about the Solar Energi concept is that it’s all made from off-the-shelf components today. The only hangup is, who would accept liability for a car that rolled—even on purpose—all by itself?
Learn more about electric cars in our guide to alternative fuels.