Charge Controller as name suggest is meant for controlling the charging of battery or work as regulator to protect battery from overcharge and block a reverse current. If a non-self-regulating solar array is connected to lead acid batteries with no overcharge protection, the life of your batteries will be highly compromised. Simple controllers contain a transistor that shunt the PV charging circuit, terminating the charge at a pre-set high voltage and, once a pre-set reconnect is reached, opens the shunt, allowing charging to resume. In the solar sector for electricity generation, greater attention is being given to photovoltaic conversion. The solar charge regulator main task is to charge the battery and to protect it from overcharging and deep discharging. Deep discharging could also damage the battery.
Essentially 2 type of charge controllers are found in the market.
- Pulse Width Modulation (PWM) -: The PWM controller is in essence a switch that connects a solar array to the battery. The result is that the voltage of the array will be pulled down to near that of the battery.
- Maximum Power Point Tracking (MPPT) -: The MPPT controller is more expensive, revolutionary, innovative and sophisticated device. It adjust its input voltage to harvest the maximum power from the solar array and then transform this power to supply the varying voltage requirement of the battery plus load. it essentially decouples the array and battery voltages so that there can be, for example, a 24 volt battery on one side of the MPPT charge controller and panels wired in series to produce 36 volts on the other.
MPPT outperform PWM in a cold climate, while both controllers will show approximately the same performance in a subtropical to tropical climate.