Solar charge controller – how to choose the right one?

The charge controller is a key part of the system to ensure that solar panels work highly efficiently. The energy received from the solar panels is distributed using the controller. Also, the regulator helps to maintain the desired output voltage in order to avoid discharging or, on the contrary, overcharging the battery. And this is the prolongation of the life of the entire solar system. It is important to remember that the selection of a charge controller is a responsible business and sometimes some experts make mistakes. How can you avoid such costly blunders? Let’s figure it out together.

– So, the charge controller for solar panels must be selected taking into account the battery current. To do this, we take the power of the battery and divide this value by the voltage of the entire system. As a result, we get the value of the required rated current. Some experts calculate this value based on the rated current of the battery. This is justified in the case of using a PWM type device, since here the voltage, current of the battery and the battery are the same. But if an MPPT controller system is used, then the battery current is two orders of magnitude higher than that of the solar panel. So, when buying a controller, be guided by the battery current.

The open circuit voltage is not the maximum power threshold, but the value that is equal to the controller input voltage. If the maximum input voltage is exceeded, an emergency may occur. If you do not plan to give full load to the battery, still equip it with a controller that matches the rating. Since if its technical characteristics are weaker than necessary for the power of the solar system, the device will fail much faster.

Note that some of the owners of solar equipment decide that their batteries can work in an economical mode during the winter period. That is, they reduce the number of batteries, put the controller, where the rating is lower. It is believed that in winter the sun shines less intensely, so the charge will be less. And in the coming summer, the solar charge controller will simply reduce the power of the photovoltaic modules, and this will be fine, because there is enough power. From the outside it seems that the solution is good. But actually it is not. The calculation of solar energy production takes into account the monthly average over the last several years of use. In addition, the sun’s energy and intensity is very uneven in the northern regions. As a result, when we cut the battery and controller, the efficiency of the system drops to zero.