MPPT Regulators - Maximum Power Point TrackingSimple PWM Budget PWM Premium MPPT
A Maximum Power Point Tracker (MPPT) controller constantly monitors ("tracks") the voltages of the battery and the solar array and then calculates the optimum charging voltage. This usually means the voltage is dropped, but unlike conventional regulators, the MPPT controller turns the remaining "unused" voltage into current (Amp) for charging. A traditional regulator would not know what to do with the excess voltage. Some MPPT controllers claim 15-40% gain compared to PWM regulators.
While it is best to match the solar array voltage with the battery bank (e.g. both nominal 12V), MPPT regulators accept a higher panel to battery voltage, e.g. a 48 volt solar array to a 12 volt battery bank and still charge your batteries properly. Another advantage is that your solar array can be further away from the regulator while using reasonable cable sizes (the higher the voltage, the skinnier the cable).