Output voltage to the battery, solar panels must be higher than the current voltage of the battery, if the voltage is lower than the battery voltage of solar panels, then the output current will be close to zero. So, in order to be on the safe side, when solar panel manufacturing factory, the peak voltage of solar panels (Vpp) around 17 v, this is when the environment temperature is 25 ° C set of standards. When the weather is very hot, the solar panel's peak voltage Vpp will drop to about 15V, but in cold weather, the solar peak voltage Vpp can reach 18V.
Now, let's look back at the difference between the MPPT solar controller and the traditional solar controller. Traditional solar charge controller is a bit like manual gearbox, increased when the speed of the engine, if the transmission gear does not improve accordingly, is bound to affect the speed. But for MPPT solar controller, charging parameters are set in before they leave, that is to say, the MPPT controller can track maximum power point of solar panels, to show the most powerful of the solar panels. The higher the voltage is, the more power can be generated by the maximum power tracking, thus increasing the charging efficiency. In theory, using the MPPT controller of solar power system will be more efficient than the traditional 50%, but according to our actual test, because of the influence of the environment and all kinds of energy loss, the efficiency can be increased by 20% - 30%.
In this sense, the MPPT solar charge and discharge controller will eventually replace the traditional solar controller.