An independent photovoltaic power generation system is also called an off-grid photovoltaic power generation system. A typical independent photovoltaic power generation system consists of a solar array and a battery connected to it. In sunny days, the photovoltaic array provides power to the load and charges the battery, and in other cases, the battery provides power to the load. The inverter converts the dc power of the array and battery into 60Hz or 50Hz power.
Classification of independent photovoltaic systems
An independent photovoltaic power generation system is mainly composed of solar cell modules, controllers, and batteries. To supply power for ac loads, an AC inverter needs to be configured. Independent photovoltaic systems can be divided into TWO categories: DC photovoltaic power generation system and AC photovoltaic power generation system.
First, DC photovoltaic power generation
1. Dc photovoltaic power generation system without battery
The characteristic of the DC PHOTOVOLTAIC power generation system without batteries is that the electrical load is DC load, and there is no requirement for the service time of the load, and the load is mainly used in the daytime. The solar cell is directly connected to the electrical load. When there is sunlight, it generates electricity for the load to work. When there is no sunlight, it stops working. The system does not require the use of controllers, and there is no battery storage device. The advantage of the dc photovoltaic power generation system without batteries is that the loss caused by the energy passing through the controller and the storage and release of batteries is eliminated, and the utilization efficiency of solar energy is improved. The most typical application of such systems is solar photovoltaic water pumps.
2. Dc PHOTOVOLTAIC power generation system with battery
The DC PHOTOVOLTAIC power generation system with batteries is composed of solar cells, charge and discharge controllers, batteries and DC loads. With sunlight coming in, the solar cell converts light energy into electricity for the load and simultaneously stores electricity to the battery. At night or rainy days, the battery supplies power to the load. This system is widely used, ranging from solar lawn lights and garden lights to mobile communication base stations and microwave transfer stations far from the power grid and power supply in remote rural areas. When the system capacity and load power is large, it is necessary to equip the solar cell array and battery. [3]
Ac photovoltaic power generation
1, AC and AC, DC hybrid photovoltaic power generation system
Ac and AC, DC hybrid photovoltaic power generation system compared to THE DC photovoltaic power generation system, the AC photovoltaic power generation system has an AC inverter, which is used to convert the direct current into ac power to provide power for the AC load. Ac and DC hybrid photovoltaic power generation system can supply power for BOTH DC and AC loads.
2. Municipal complementary photovoltaic power generation system
The municipal complementary photovoltaic power generation system is based on solar photovoltaic power generation in the independent photovoltaic power generation system, supplemented by ordinary 220V AC power. In this way, the capacity of solar cells and batteries in the photovoltaic power generation system can be designed to be smaller. Basically, when there is sunshine on the day, the electricity is generated by solar energy, and when it is rainy, the municipal power energy is used to supplement. Most areas of Our country have more than 2/3 of the good weather for many years, which reduces the one-time investment of solar photovoltaic power generation system, and has significant energy-saving and emission reduction effect. It is a good way to promote and popularize solar photovoltaic power generation at this stage.
Application examples of municipal complementary photovoltaic power generation system. In the renovation of street lamps in an urban area, if all the ordinary street lamps are replaced by solar street lamps, the one-time investment is very large and cannot be realized. And if the ordinary street lamps are modified, keep the original mains power lines and light pole, replace the energy-saving light source of lamps and lanterns, in the form of mains complementary photovoltaic, with small capacity of solar batteries and battery (barely enough to use in the day, also does not consider the continuous rainy days), constitutes the utility complementary solar street lamps, halve investment, energy saving effect.
