12v solar charge controller is used to keep the battery from overcharging by regulating the voltage and current coming from the solar panel to the battery. It is programmed at 15-A/200-W unit and uses MPPT (maximum power point tracking) to accelerate solar charging of the battery up to 30% per day. The role of the charge controller is to ensure that the battery is not overcharged. There is a bewildering array of commercial devices from a large number of manufacturers, with current ratings from a few amps up to hundreds of amps, and operating voltages generally in multiples of 12 V up to 48 V (nominal battery voltage). Most commercially available charge controllers for PV applications use a switched series regulator to control the charging current Fig. 14A.