Ever since the Volt concept was first introduced in January 2007 a lot of people have voiced the opinion that solar panels on the roof would be a good idea. Those who understand the current costs of solar panels and their energy output usually determine that the amount of energy which could be contributed to the batteries is relatively quite small.
Nonetheless it seems to have some strong green-cred marketing value.
All this talk might even have led GM to consider having such an option for the Volt as Bob Lutz recently alluded to .
Today news has come out of Japan that the next generation Toyota Prius will offer a solar roof option. The panels will be made by Kyocera and "the power generated by the system would be used for the air conditioning."
Source ( Reuters )