It's too difficult and expensive for solar panels to power the motors in hybrid cars, so they typically assist smaller systems like the air-conditioning unit.

AP Photo/Kiichiro Sato

Hybrid Car Solar Roof Panels

There are several car companies that plan to install solar panels in their newer hybrid vehicles. Some third generation models of the Toyota Prius and the Karma, a plug-in hybrid made by Fisker Automotive, will get solar power. Even the Audi A8, a conventional car powered by a gasoline engine, uses solar panels. The big question for most of these manufacturers is: how much extra power will a solar roof panel actually provide? Can they boost the electric range for fuel-efficient vehicles like hybrids and make eco-friendly driving even friendlier and sunnier?

The answer, for the most part, is no. In the case of the 2010 Toyota Prius, an unidentified source from Toyota noted that the company's use of a solar panel in the hybrid car was more of a "symbolic gesture" than a useful source of propulsion, explaining that it's very difficult to generate enough power to move a vehicle with energy from the sun's light [source: Reuters.com]. So, solar panels generally don't have any impact on a hybrid car's fuel efficiency. Solar panels are also made out of silicon, which for the moment is too expensive for automakers to use as a viable source. In fact, a few car companies have tried in the past to install solar panels, with little or no luck. Mazda, for instance, attempted to market solar panels on two of its models sold outside of the U.S., the Eunos 800 and the Sentia, in 1992, but the system proved to be too costly and unpopular with drivers.

So what will solar panels do on top of hybrid cars if they're not powering the electric motor? The panels, built by the Kyocera Corporation, will power at least part of the Toyota Prius' air-conditioning unit. The solar panel will be available as an option on the Prius, so customers will pay extra for this feature. Smaller, less power-hungry systems seem to work better with solar power, a fact highlighted by the Audi A8, a conventional gasoline-powered car that employs solar panels for powering its air-conditioning system.

For lots more information on solar power, hybrid cars and green driving, follow the links on the next page.