Toyota tests solar-powered Prius in quest for plugless electric car

In the Japanese government-funded demonstration project, Toyota engineers fitted solar panels designed by Sharp Corp to the hood, roof, rear window, and spoiler to see just how much juice the sun can generate.

The electricity from the panels goes directly to the drive battery, so the Prius can charge while moving or when parked.

On a good day, the charge can be sufficient for up to 35 miles of travel.

But performance drops off quickly if it is cloudy, or even when it's too hot, which affects the solar panel's performance.

Making the entire package lighter, and bringing down the extremely high cost of the technology are among the biggest challenges to be faced before commercialization.