A PWM solar charge controller is the traditional style. They are robust, inexpensive and widelyused in solar panel applications. PWM shunt controllers are used less often andmostly in applications where electrical interference is an issue.

       The MPPT (Maximum PowerPoint Tracking) solar controller is the shining star of today's solar systems.These controllers actually detect the optimum operating voltage and amperage ofthe solar panel array and match that with the battery bank. The result isadditional 15-30% more power out of your solar array versus a PWM solar controller. Although the MPPT controller is more expensive than its PWM counter part, it is generally worth the investment for any solar electric systemover 200 watts.