A Pulse Width Modulation (PWM) charge controller and a Maximum Power Point Tracking (MPPT) charge controller are both devices that regulate the flow of power from a solar panel to a battery bank, but they do so in different ways.
A PWM charge controller uses a switching mechanism to regulate the flow of power from the solar panel to the battery bank. It works by repeatedly turning the power on and off very quickly, in a process known as pulse width modulation. This allows the controller to regulate the voltage and current flowing into the battery bank to prevent overcharging and over discharging. PWM charge controllers are relatively simple, inexpensive, and easy to use, but they are not as efficient as MPPT charge controllers.
An MPPT charge controller, on the other hand, uses a more sophisticated algorithm to track the maximum power point of the solar panel and regulate the flow of power accordingly. It can increase the efficiency of the system by as much as 30% compared to PWM charge controller. Solar panels perform best when they are operating at their maximum power point, which is the point on their power-voltage curve where they produce the most power. The MPPT charge controller uses this information to regulate the flow of power from the solar panel to the battery bank in the most efficient way possible. MPPT charge controllers are generally more expensive than PWM charge controllers, but they are also more efficient and can help to increase the overall performance of your solar power system.
In summary, PWM charge controllers are simple and inexpensive, but not as efficient as MPPT charge controllers. MPPT charge controllers are more expensive, but they can increase the overall efficiency and performance of your solar power system.