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Solar-powered Ford C-Max Energi chases the sun by itself

Would you buy a car that moves all by itself?

Published: March 17, 2014 10:00 AM

It’s strange enough to ride around in a self-driving car. But it may be even weirder seeing a car drive itself around with no one inside. That’s what Ford is proposing with its C-Max Solar Energi concept.

Originally previewed at the 2014 CES show, the car recently reappeared at the Washington Auto Show, along with Mike Tinskey, Ford’s global director of vehicle electrification and infrastructure, who was there to explain it all. The C-Max Solar Energi concept comes with its own car port, with transparent solar collectors for the roof that effectively act as a bunch of magnifying glasses. Tinskey says the car port can be assembled with common tools by any owner and transported, as necessary.

The purpose for the car port is to charge the car’s batteries with solar power. That way, the owner wouldn’t necessarily need an electrical outlet to plug in. (Read our complete Ford C-Max road test.)

But the problem with solar-powered cars is that conventional cars don’t offer sufficient surface area to collect enough solar radiation to charge their large batteries. (Tiny dedicated competition solar cars are much more efficient, because they carry only one person, usually lying on their back, and run on bicycle tires. Even the small batteries they use require the entire surface of the car to face up toward the sun and be covered with solar panels—something a traditional car shape, with its vertical sides, wouldn’t allow.)

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.

––Eric Evarts

* Correction:

The output of the C-max Solar Energi's rooftop solar panel has been corrected. 2:45 p.m. 3/24/14

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