A charge controller is the device that manages the flow of energy from the PV array to the battery bank. It prevents overcharging (which damages batteries) and implements the optimal charging profile for the battery chemistry. Maximum Power Point Tracking (MPPT) charge controllers, which continuously adjust the operating voltage of the PV array to extract maximum power, are significantly more efficient than older Pulse Width Modulation (PWM) controllers and are the standard choice for properly designed systems.

An inverter converts the DC electricity from the battery bank to the AC electricity needed by most appliances and building systems. A battery-based inverter (also called an inverter-charger) combines the inverter function with battery charging, allowing the system to charge batteries from a generator or grid connection when available. Inverter sizing is determined by the peak simultaneous load that the system must supply: the inverter must be able to handle all loads that might be running at the same time, including the surge currents of motors at startup.