Composition: The photovoltaic system is basically composed of four parts: 1. Solar cell modules; 2. Battery pack; 3. Battery charging and discharging controller, also known as DC controller; 4. DC load or AC load. In addition, if the load is AC, an AC inverter power supply should also be equipped for the AC load, which can be regarded as a DC load subsystem together with the AC load.
Principle: (1) Solar cell modules generate photovoltaic voltage and photocurrent under sunlight exposure, and are the power generation devices of photovoltaic systems. It outputs direct current, which is set by the charging and discharging controller to charge the battery; The process of charging is the process of energy storage.
(2) A battery is the energy storage device of a photovoltaic system. During the day, solar energy is converted into electrical energy by photovoltaic cells. By charging the battery, electrical energy is then converted into chemical energy. At night, the solar cells stop generating electricity and charging, and the batteries begin to discharge the load. Chemical energy is then converted into electrical energy to supply the light source. So, a complete photovoltaic system undergoes a series of energy transformations during the day and night: solar radiation energy → electrical energy → electrochemical energy → electrical energy → electro-optic lighting.
(3) The intelligent charging and discharging controller plays an extremely important control role in the energy conversion of photovoltaic systems. This controller has advanced charging control, discharge control, as well as a series of protection functions such as overcharge protection, over discharge protection, overload protection and reverse connection protection. The performance of photovoltaic systems is closely related to the controller, and it can be said that the charge and discharge controller is the heart of photovoltaic systems. At present, the charging and discharging controllers used in photovoltaic systems are closely monitored by microcontrollers, especially during the charging process, greatly improving system reliability.
