Through the employment of the Charge Controller, "solar panel power" is converted into a form that may be utilized by the batteries. Maximum Power Point Tracking, or MPPT, has to do with the solar cell itself. Every solar cell has a maximum power output point that is determined by the cell's output of voltage (V) and current (I). With MPPT, you can be confident that your solar panels are producing as much power as possible at all times. It works very well when there is little light.