A maximum power point tracker (or MPPT) is a high efficiency DC to DC converter which functions as an optimal electrical load for a photovoltaic (PV) cell, most commonly for a solar panel or array. Any application which the PV module is the energy source, MPPT is used for detecting the variations in the current-voltage characteristics of solar cell. MPPT solar charge controller is necessary for any solar power system that needs to extract maximum power from PV module; it forces the PV module to operate at voltage close to maximum power point to draw maximum available power. MPPT allows users to use PV module with a higher voltage output than operating voltage of battery system.
For example, if the PV module has to be placed far away from charge controller and battery, its wire size must be increased to reduce voltage drop. With a MPPT solar charge controller, users can wire the PV module for 24 or 48 V (depending on charge controller and PV modules) and bring the power into 12 or 24 V battery system. This means it reduces the wire size needed while retaining full output of PV module. The benefits of MPPT solar charge controllers are greatest during cold weather, on cloudy or hazy days or when the battery is deeply discharged.