Charge controllers are used as a separate component in battery based systems to insure maximum power from the solar array and extend battery life. A charge controller senses the battery state of charge by monitoring its voltage.
Overcharging will cause physical battery damage so a charge controller’s primary duty is to limit, and eventually shut off input as the battery approaches the full mark.
Charge controllers are integral to grid-tied inverter electronics. Gulf South Solar recommends MPPT charge controllers to optimize your array output.