I'm solving your battery recharging problem, because most electricity still comes from coal.
Build yourself a solar cooker like this, and then build yourself a water reservoir at the point where all the sunlight is concentrated.
From that point on I'm still not quite sure, but when the water comes to a boil, the steam is supposed rush through a hose and run past generators on the ground. With something this small I doubt you'll get much power, but nevertheless, maybe you should look into it.
Or just forget the whole power concept and use it like it's supposed to be used...