Unless you plan on using battery power for everything, you will need a Power Inverter. Since the majority of modern conveniences all run on 120 volts AC, the Power Inverter will be the heart of your Solar Energy System. It not only converts the low voltage DC to the 120 volts AC that runs most appliances, but also can charge the batteries if connected to the utility grid or a AC Generator as in the case of a totally independent stand-alone solar power system.