Solar panels on cars are another option. I used to think that was a bad idea, considering that an electric vehicle uses vastly more power than solar panels could ever hope to generate. Then I thought about my own driving patterns; On a typical work day, I drive about three miles to work, park in the sun for 8 hours, and then drive three miles home. With an electric vehicle and a solar panel on the roof, I might not even have to plug it in except on long trips. Even if that wasn't true, if a solar panel could save me, say, 10 full charges per year, it's probably worth a little extra weight and cost.