Solar photovoltaic power generation systems can be divided into two categories according to their relationship with the power system

Solar photovoltaic power generation systems can be divided into two categories according to their relationship with the power system: Stand-alone PV System and Grid-connected PV System.
Independent photovoltaic power generation system
The independent photovoltaic power generation system is composed of solar photovoltaic array, battery pack, charge controller, power electronic converter (inverter), load and so on. Its working principle is that the solar radiation energy is first converted into electrical energy through the photovoltaic array, and then converted by the power electronic converter to supply power to the load. At the same time, excess electrical energy is stored in the energy storage device in the form of chemical energy after passing through the charge controller. In this way, when the sunshine is insufficient, the energy stored in the battery can be converted into AC 220V, 50 Hz electrical energy for AC loads after being boosted by power electronic inverters, filters and power frequency transformers. The characteristic of solar power generation is that it generates electricity during the day, but the load often consumes electricity around the clock. Therefore, energy storage components are essential in independent photovoltaic power generation systems, and the energy storage components used in engineering are mainly batteries.
Grid-connected photovoltaic power generation system
Grid-connected photovoltaic power generation system consists of photovoltaic array, high-frequency DC/DC boost circuit, power electronic converter (inverter) and system monitoring part. Its working principle is that after the solar radiation energy is converted by the photovoltaic array, it is converted into high-voltage direct current by high-frequency direct current, and then it is inverted by the power electronic inverter to output a sinusoidal alternating current with the same phase frequency as the grid voltage to the grid.
The biggest difference between the above two photovoltaic power generation systems is that the grid-connected photovoltaic power generation system is directly connected to the grid, so the power surplus of the photovoltaic array and the parallel grid can complement each other, eliminating the need for energy storage such as batteries in the independent photovoltaic power generation system components, not only reduces the system cost, but also ensures the reliability of the system. At the same time, in summer, the solar radiation intensity is high, and the photovoltaic system generates a lot of power, which can regulate the peak load of the grid in summer. With the large-scale application of solar photovoltaic power generation and the rapid decline in the price of solar cell components in recent years, grid-connected systems will undoubtedly be more widely used.