According to different applications, solar photovoltaic power generation systems are generally divided into five types: grid connected power generation systems, off grid power generation systems, grid connected energy storage systems, and multi energy hybrid microgrid systems.

1、 Grid connected photovoltaic power generation system

The grid connected photovoltaic system consists of photovoltaic modules, photovoltaic grid connected inverters, photovoltaic meters, loads, dual circuit meters, grid connected cabinets, and the power grid. The direct current generated by photovoltaic modules is converted into alternating current through an inverter, supplied to the load, and sent to the power grid. There are two main modes of photovoltaic grid connected systems, one is "spontaneous self use, residual electricity online", and the other is "fully online".

Distributed photovoltaic power generation systems generally adopt a mode of "self use and surplus power grid connection". The electricity generated by solar cells is prioritized for use in the load. When the load is not fully utilized, excess electricity is sent to the grid. When the power supply to the load is insufficient, the power grid and photovoltaic system can simultaneously supply power to the load.

2、 Off grid photovoltaic power generation system

Off grid photovoltaic power generation systems do not rely on independent operation of the power grid and are generally used in remote mountainous areas, areas without electricity, islands, communication base stations, street lights, etc. The system generally consists of photovoltaic modules, solar controllers, inverters, batteries, and loads. The off grid power generation system converts solar energy into electrical energy under lighting conditions, and the solar energy controls the inverter to supply power to the load while charging the battery; When there is no light, the AC load is powered by the battery through the inverter.

It is very practical for areas without power grids or areas with frequent power outages.

3、 Grid connected photovoltaic energy storage system

Off grid photovoltaic power generation systems are widely used in places with frequent power outages or where there is no excess electricity for photovoltaic self use. The self use electricity price is much higher than the grid electricity price, and the peak valley electricity price is much higher than the low valley electricity price.

The system consists of photovoltaic modules, solar integrated machines, batteries, loads, etc. The photovoltaic array converts solar energy into electrical energy under lighting conditions, and the solar energy controls the inverter to supply power to the load while charging the battery; When there is no light, the battery supplies power to the solar controlled inverter and then to the AC load.

Compared with grid connected power generation systems, this system has added charging and discharging controllers and batteries. When the power grid loses power, the photovoltaic system can continue to operate, and the inverter can switch to off grid mode to supply power to the load.

4、 Grid connected energy storage photovoltaic power generation system

Grid connected energy storage photovoltaic power generation systems can store excess electricity and increase the proportion of spontaneous self use. The system consists of photovoltaic modules, solar controllers, batteries, grid connected inverters, current detection devices, and loads. When the solar power is less than the load power, the system is powered by solar energy and the grid. When the solar power exceeds the load power, a portion of the solar power supplies power to the load, and a portion of the solar power is stored and inexhaustible through the controller.

5、 Microgrid system

Microgrid is a new type of network structure, which is a distribution network composed of distributed power sources, loads, energy storage systems, and control devices. It can convert dispersed energy into electricity on site and then supply local loads nearby. A microgrid is an autonomous system that can achieve self-control, protection, and management. It can be connected to the external power grid or operate independently.

Microgrid is an effective combination of various types of distributed power sources, which can achieve complementary advantages and improve energy utilization efficiency. It can fully promote the large-scale integration of distributed power generation and renewable energy, and achieve high reliable supply of various forms of energy. It is an effective way to achieve active distribution networks and a transition from traditional power grids to smart grids.