MPPT or ‘maximum power point trackers’ are far more advanced than PWM controllers and enable the solar panel to operate at its maximum power point, or to be more precise, the optimum voltage for maximum power output. Using this clever technology, MPPT solar charge controllers can be up to 30% more efficient, depending on the battery voltage and operating voltage (Vmp) of the solar panel. The reasons for the increased efficiency and how to correctly size an MPPT charge controller is explained in detail below. As a general guide, MPPT charge controllers should be used on all higher power systems using two or more solar panels, or whenever the panel voltage (Vmp) is 8V or higher than the battery voltage - see full explanation below.