Traditional PV inverters mostly use a two-stage circuit architecture. The front stage is a step-up DC-DC converter, and the latter stage is a full-bridge DC-AC converter. The control technology is relatively mature and simple. This architecture requires two power conversions, and the overall efficiency of the system is difficult to improve.

　　The new-style PV inverter adopts a single-stage circuit architecture. The DC voltage of the PV cell must be higher than the peak value of the output voltage. Its control principle is like a voltage-to-current bidirectional PWM DC-AC converter. Since the maximum power conversion control and the output current synchronization waveform control must be taken into account, a complex nonlinear control problem is formed, and the control link is more complicated.

　　According to the output form, PV inverters can be divided into single-phase and three-phase. Generally, systems below 3 kVA are mostly single-phase, between 3-5 kVA, both are available, and above 5 kVA are mostly three-phase mode.

　　According to the overall framework, PV inverters can be divided into power frequency inverters and high frequency inverters.

　　The insulation method of the power frequency inverter is simple in circuit, low in switching frequency, small in electromagnetic interference, high in efficiency, and low in manufacturing cost. It does not use SPWM control, and the output is a rectangular wave. This requires strong filtering measures at the output to make the output sinusoidal waveform distortion <5%. Since there are few semiconductor devices in the circuit, it can adapt to relatively harsh conditions. This type of inverter is mainly used in stand-alone PV power stations.

　　The main circuit of the high-frequency inverter is divided into three stages (DC-HFAC-DC-LFAC). The first stage is an SPWM high-frequency inverter, which is rectified and filtered into a direct current through a high-frequency transformer, and then passed through a power frequency inverter. It becomes a power frequency sine wave voltage output. It has the advantages of small size, light weight and low cost. However, because of the need for multi-stage conversion and low efficiency, only low-loss absorption circuits and electronic components can be used. Due to SPWM control and frequency conversion, the output waveform has little distortion and does not require strong filtering. The problem of high-frequency electromagnetic interference is serious, and suppression measures such as filtering and shielding must be adopted. This type of inverter is mainly used in grid-connected PV power stations.

　　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.