Time for Solar! I got 250 of these 0.5V 3A crystaline solar cells when Evergreen Electric went out of business and had to liquidate their inventory. Twenty five of them in series produces the 12.5 volts ideal for charging a 12v car battery. (batteries need to be charged at a slightly higher voltage than they operate at). I’m using a commercial solar charge controller because I’m too lazy to design and build my own.