I'm new to this forum, so I'm not sure if this is the appropriate section to post my question, but anyway, here it is: I'm looking into buying a solar panel to be permanently connected to my 12V car battery and recharge it constantly (or at least when the sun is up). I want to do this to experiment with the idea of shutting my car off at stop lights to conserve fuel, then restart the engine when the light turns green, similar to how at Toyota Prius works, and see how effective it is at saving fuel. Since starting the car requires a lot of energy from the battery, I'm afraid that doing this 5-10 times a day almost everyday will significantly reduce the life of the battery. I've been looking into using solar panels that I can rig on the hood or roof of the car so the battery is contantly charged; however, I can't find any clear answers as to how effective they are at recharging a 12V car battery. How many watts would I need for this kind of setup to get any significant recharging? Is this even a good idea to begin with or is it just a pipe dream?