Classification of Grid-Connected Photovoltaic Power Generation Systems

Grid-connected photovoltaic power generation systems can be classified according to system functions and whether the generated electric energy can be returned to the power system.

Classification of Grid-Connected Photovoltaic Power Generation Systems according to Function

According to the system function, it can be divided into two categories: one is the unscheduled photovoltaic grid-connected power generation system with no implicit battery link; The other is a scheduling photovoltaic grid-connected power generation system with storage batteries. Scheduling photovoltaic grid-connected power generation system adds energy storage link. The system first charges the battery, and then uses the system as grid-connected or independent after inversion according to the needs. The working time and grid-connected power of the system can be set artificially. Although on the surface, the schedulable grid-connected system has more functions than the unscheduled system, it has brought many serious problems due to the addition of energy storage links, so the current photovoltaic grid-connected system is mainly unscheduled system. Unschedulable photovoltaic grid-connected power generation system has high integration, relatively convenient installation and debugging, and high reliability.

Classification of Grid-Connected Photovoltaic Power Generation Systems according to the Electric Return

According to whether the generated electric energy can be returned to the power system, it can be divided into countercurrent type, non-countercurrent type, switching type, direct and alternating current type, mixed type and regional type.

(1) DC-AC grid-connected power generation system, which is to directly supply the direct current generated by photovoltaic grid-connected inverter power generation system to electrical equipment. This system is sometimes used with power system, and its main purpose is to improve the reliability of power supply.

(2) Hybrid grid-connected power generation system When the power provided by solar photovoltaic power generation is insufficient (such as continuous rainy weather, short sunshine time in winter, etc.), other power generation systems such as wind power generation and fuel cell power generation can be combined with photovoltaic power generation system. Such systems are called hybrid grid-connected power generation systems, such as solar photovoltaic, fuel cell grid-connected power generation system and wind-light complementary grid-connected power generation system. Wind-light complementary system uses both solar energy and wind energy to generate electricity, so it makes use of meteorological resources. It can generate electricity day and night. Under suitable weather conditions, wind-solar hybrid system can improve the continuity and stability of power supply. Usually, when there is no sunshine at night, the wind is strong, so the complementarity is good, and the solar panel configuration of the system can be reduced, thus greatly reducing the system cost. The initial investment and power generation cost per unit capacity of the system are lower than those of the independent photovoltaic system. The system can supply power (sell electricity) to the power grid system when the power generation is surplus; When the power generated by this system is insufficient, it can be supplied by the power grid system (electricity purchase).

(3) Counter-current solar grid-connected power generation system, when the solar photovoltaic system generates sufficient electric energy, the surplus electric energy can be supplied to the power grid system; When the power provided by the solar photovoltaic system is insufficient, the external power system can be used for power supply. This kind of system is called countercurrent grid-connected power generation system.

(4) The photovoltaic grid-connected inverter power generation system without countercurrent grid-connected power generation system does not supply power to the power system even if the power generation is abundant, but when the power supply of the solar photovoltaic power generation system is insufficient, it can be supplied by an external power system. This kind of system is called non-countercurrent grid-connected power generation system.

(5) Switching grid-connected power generation system, which can be divided into the following two types: switching grid-connected power generation system and self-running switching grid-connected system.