PV inverters can be divided into two types: centralized and distributed. Distributed inverters include two types: string type and micro type. As for the distributed inverter, which is gradually being used, it has both centralized and string characteristics.

　　Centralized inverter systems generally use a single MPPT. A single MPPT is equipped with 2-12 sets of PV strings. The power of each MPPT can reach 125-1000KW, and the unit capacity is usually above 500KW. It is mainly used in large-scale projects such as ground PV power stations with good lighting conditions. The working principle is to converge and Maximum Power Peak Tracking (MPPT) of the direct current generated by the work of multiple PV modules, and then centrally inverts the direct and alternating current conversion, and start grid-connected operation after boosting.

　　The centralized inverter has the characteristics of large capacity, which can reduce system cost and circuit loss, and facilitate centralized management. At the same time, it also has the advantages of effectively reducing harmonics, high integration, simple control, relatively mature technology, and low cost.

　　Due to the large number of PV strings connected to a single MPPT and the narrow working voltage range of the centralized inverter, it is impossible to accurately control each PV string, so it cannot guarantee that each string is at its best. The operating point ultimately reduces the overall power generation efficiency of the system.

　　The operating voltage range of the centralized MPPT is generally in the range of 500-850V, and the adjustability is poor. Under unsatisfactory lighting conditions such as rainy and cloudy conditions, the voltage of the system is lower than the minimum working voltage of the inverter MPPT, which causes the system to fail to perform normal power generation work. At the same time, due to its access to multiple sets of DC inputs, the PV system requires good consistency between the components. Once one of the components fails, it will affect the overall efficiency of the system.

　　Due to the large capacity of the single unit, the volume and weight of the centralized inverter are relatively large, and a special equipment room needs to be established outdoors for placement. This not only increases the overall land cost, but also increases the difficulty of installation. Because the inverter generates heat when it is working, and the machine room needs a certain degree of airtightness, this creates a heat dissipation problem.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect replacement for lead-acid batteries, and they are the first choice for grid-connected peak shaving, off-grid energy storage, PV energy storage, UPS, data center and other industries.

　　Solar power generation system with lithium battery energy storage system is a very promising clean energy.