Home > Knowledge > Content
What is MPPT (Solar Charge Controller)
- Apr 13, 2018 -

MPPT Overview


The MPPT system is an electrical system that enables the photovoltaic panel to output more electrical power by adjusting the working state of the electrical module, and can effectively store the direct current generated by the solar panel in the storage battery, effectively solving the problem that the conventional grid cannot be covered. Life and industrial electricity in remote areas and tourist areas do not generate environmental pollution.

The output power of a photovoltaic cell is related to the operating voltage of the MPPT controller. Only when operating at the most suitable voltage, will its output power have a unique maximum value.

The sunshine intensity is 1000 W/down, U=24V, I=1A; U=30V, I=0.9A; U=36V, I=0.7A; visible output power is maximum under the voltage of 30.

The principle of MPPT


To charge the battery, the output voltage of the solar panel must be higher than the current voltage of the battery. If the voltage of the solar panel is lower than the voltage of the battery, the output current will be close to zero. Therefore, for the sake of safety, the peak voltage (Vpp) of the solar panel is about 17V when the solar panel is manufactured. This is set at the standard when the ambient temperature is 25°C. When the weather is very hot, the peak voltage Vpp of the solar panel will drop to about 15V, but in cold weather, the peak voltage of solar energy 

Vpp can reach 18V.

The traditional solar charge-discharge controller is a bit like a manual gearbox. When the engine speed increases, if the transmission gear does not increase accordingly, it will certainly affect the speed. However, for the conventional controller, the charging parameters are set before shipping, that is, the MPPT controller will immediately track the maximum power point in the solar panel to achieve the maximum efficiency of the solar panel. The higher the voltage, the more power can be output through maximum power tracking, thereby improving the charging efficiency. In theory, the solar power system using the MPPT controller will be 50% more efficient than the traditional one, but according to our actual tests, the final efficiency can also be increased by 20%-30% due to the environmental impact and various energy losses. .

In this sense, the MPPT solar charge-discharge controller is bound to replace traditional solar controllers.

MPPT features

The main function of the MPPT controller is to detect the main circuit DC voltage and output current, calculate the output power of the solar array, and realize the tracking of the maximum power point. The perturbation resistor R and the MOSFET are connected in series. Under the condition that the output voltage is basically stable, the average current through the resistor is changed by changing the duty cycle of the MOSFET, so that a disturbance of the current is generated. At the same time, the output current and voltage of the photovoltaic cell will also change. The output power and voltage of the photovoltaic cell before and after the disturbance are measured to determine the direction of the disturbance in the next cycle. When the direction of the disturbance is correct, the output power of the solar energy solar panel increases. The cycle continues to oscillate in the same direction. Conversely, it oscillates in the opposite direction. As such, perturbations and observations are repeatedly performed to make the solar photovoltaic panel output reach the maximum power point.