For linear circuits, when the load resistance is equal to the internal resistance of the power supply, the power supply has the maximum power output. Although photovoltaic cells and DC/DC converter circuits are strongly non-linear, they can be considered as linear circuits in a very short time. Therefore, as long as the equivalent resistance of the DC-DC conversion circuit is adjusted so that it is always equal to the internal resistance of the photovoltaic cell, the maximum output of the photovoltaic cell can be realized, and the MPPT of the photovoltaic cell is realized.
In general, the MPPT controller tracks the maximum power point in the solar panel in real time to maximize the effectiveness of the solar panel. The higher the voltage, the more power can be output through the maximum power tracking, thus improving the charging efficiency.