Classification and introduction of solar photovoltaic power generation systems
Definition of photovoltaic system: photovoltaic system is a system that uses solar cell components and other auxiliary equipment to convert solar energy into electrical energy.
Generally, we divide photovoltaic systems into independent systems, grid-connected systems and hybrid systems. If according to the application form of the solar photovoltaic system, the application scale and the type of load, the photovoltaic power supply system can be divided in more detail. Photovoltaic systems can also be subdivided into the following six types: small solar power system (Small DC); simple DC system (Simple DC); large solar power system (Large DC); AC and DC power supply systems (AC/DC); Grid-connected system (Utility Grid Connect); hybrid power supply system (Hybrid); grid-connected hybrid system. The working principle and characteristics of each system are described below.
1. Small solar power system (Small DC)
The characteristic of this system is that there is only DC load in the system and the load power is relatively small. The whole system has a simple structure and easy operation. Its main uses are general household systems, various civilian DC products and related entertainment equipment. For example, this type of photovoltaic system is widely used in western my country, and the load is a DC lamp to solve the home lighting problem in areas without electricity.
2. Simple DC system (Simple DC)
The characteristic of the system is that the load in the system is a DC load and there is no special requirement for the use time of the load. The load is mainly used during the day, so there is no battery or controller in the system, and the system structure is simple , Directly use photovoltaic components to supply power to the load, eliminating the need for energy storage and release in the battery, as well as energy loss in the controller, and improving energy utilization efficiency. It is often used in PV water pump systems, some temporary equipment during the day and some tourist facilities. The figure below shows a simple DC PV pump system. This system has been widely used in developing countries where there is no pure tap water for drinking, and has produced good social benefits.
3 Large solar power system (Large DC)
Compared with the above two photovoltaic systems, this photovoltaic system is still suitable for DC power supply systems, but this kind of solar photovoltaic system usually has a larger load power. In order to ensure that the load can be reliably provided with a stable power supply, its The corresponding system is also large in scale and needs to be equipped with a larger photovoltaic module array and a larger battery pack. Its common application forms include communication, telemetry, monitoring equipment power supply, centralized power supply in rural areas, beacon beacons, street lights, etc. Some rural photovoltaic power stations built in some areas without electricity in western my country adopt this form. The communication base stations built by China Mobile and China Unicom in remote areas without power grids also use this photovoltaic system for power supply. Such as the communication base station project in Wanjiazhai, Shanxi.
4 AC, DC power supply system (AC/DC)
Different from the above three solar photovoltaic systems, this photovoltaic system can provide power for both DC and AC loads at the same time. In terms of system structure, it has more inverters than the above three systems to convert DC power into AC power meets the needs of AC loads. Generally, the load power consumption of this kind of system is relatively large, so the scale of the system is also relatively large. It is used in some communication base stations with both AC and DC loads and other photovoltaic power plants with AC and DC loads.