What is the composition of photovoltaic power generation system?
Release time:
2023-08-18
Source:
Internet
A typical solar photovoltaic power generation system consists of a solar cell array (module), a cable, a power electronic converter (inverter), an energy storage device (battery), a load, I .e., a user, etc., as shown in FIG. 1. Among them, the solar cell array and the energy storage device are the power supply system, the controller and the power electronic converter are the control and protection system, and the load is the system terminal.
solar cell array
The minimum unit for photoelectric conversion is a solar cell. Its size is 4~100 cm2, the working voltage is 0.45~0.50V, and the working current is 20 ~ 25mA/cm2, so it cannot be used as a power supply alone. In a photovoltaic power generation system, solar cells need to be connected in series, parallel and packaged to form a solar cell module. Its power can be from a few watts to hundreds of watts, and it can be used as a power source alone. The solar cell array is to connect the solar cell modules in series and parallel and install them on the bracket. It can output hundreds of watts, several kilowatts or even more power, and is the electric energy generator of the photovoltaic power generation system.
The frame of the solar cell array should be as strong as possible and have sufficient hardness. At the same time to light weight. When installing the solar cell array, it is necessary to use a metal bracket with a certain strength and conducive to fixing and supporting. In some areas with harsh geographical environment or complex climate conditions, such as desert, coastal areas, polar regions, mountains, tuyeres, etc., the bracket of the solar cell array should adopt some additional measures to make it able to withstand the additional weight of strong wind and ice and snow accumulation, avoid collapse due to natural, man-made and some large animal damage.
Generally speaking, there are three types of solar cell arrays: installed on the ground, installed on the column, and installed on the roof. The specific installation form is also affected by some specific factors, such as the size of the available space, the size of the square array, the lighting conditions, the wind load, the visual effect and the difficulty of installation, the problem of destruction and theft. In the above-mentioned installation forms, it is installed on the ground because it is simple and easy to implement. The difficulty of mounting on the pillars is affected by the height of the panels from the ground. The difficulty of installing on the roof is determined by whether the roof is steep. Working on a relatively steep roof is not only time-consuming and laborious, but also very dangerous. During the installation process, it is especially necessary to avoid damage to the electrical performance of the panel. For this reason, the surface of the solar panel should be covered to reduce the probability of damage. It is also possible to build walls around photovoltaic power plants so that animals cannot approach the equipment. This ensures system security. At the same time, the installed solar panels should face the noon sun, not the direction of the compass, which is explained in the relevant information. In addition, the inclination of the solar panel to the horizontal plane is greater than 10 °. In this way, the rainwater falling on the solar panel can quickly slide down to the ground, thus keeping the surface of the panel clean.
There are many kinds of solar cell modules. According to the type of solar cell, they can be divided into monocrystalline silicon modules, polycrystalline silicon modules, gallium arsenide modules, amorphous silicon thin film battery modules, etc. Among them, crystalline silicon (including monocrystalline silicon and multi-product silicon) solar cell modules account for about 80% ~ 90% of the market. The packaging materials and processes of crystalline silicon are also different, mainly divided into epoxy resin sealing, laminated packaging silicone packaging and so on. At present, the most widely used is the vacuum lamination packaging method, which is suitable for the industrial packaging of large-area battery chips.
solar battery
Independent photovoltaic power generation systems rely on batteries to store excess electrical energy, so batteries play an important role in independent photovoltaic power generation systems. With the decline in the price of solar modules, the cost of batteries will gradually increase in the total investment in the system. In addition, in the operation of the independent photovoltaic power generation system, the normal operation of the system will be affected by the battery failure. Therefore, in the system design, select the appropriate battery type, determine the appropriate battery capacity, accurate implementation of installation, operation, careful maintenance, for the normal operation of independent solar photovoltaic power generation system is very important.
At present, there are many types of batteries commonly used in photovoltaic systems, among which the most widely used are ordinary lead-acid batteries, alkaline nickel-chromium batteries and lead-acid maintenance-free batteries. Ordinary lead-acid batteries are mainly used in low-grade occasions with maintenance capability due to their large environmental pollution and certain maintenance requirements. The waiting point of alkaline nickel-chromium batteries is that they have better low temperature, overcharge and overdischarge performance, but the disadvantage is that they are more expensive and are generally used in more special occasions. The most used battery at this stage in China is lead-acid maintenance-free battery. Its maintenance-free characteristics make its maintenance simple and convenient, reliable performance, and less environmental pollution. It is very suitable for solar power generation with high performance and reliability requirements. System, such as unattended workstations and other occasions.
Power Electronic Converter (Inverter)
Solar cell arrays produce direct current under sunlight. However, most of the common loads in daily life need to be powered by AC power, such as fluorescent lamps, televisions, refrigerators, electric fans, air conditioners, etc., as well as most power machinery. Therefore, there is a need for a device for converting direct current to alternating current, which is an inverter. The inverter in the photovoltaic power generation system is a converter circuit, and its function is to convert the direct current issued by the solar cell array into a variety of alternating current with different required frequencies and voltage values. Inverter specifically can be divided into passive and active two, passive inverter refers to the direct current through the inverter will be directly supplied to the load to use, active inverter refers to the direct current through the inverter to the AC power supply. The necessity of DC to AC is also reflected in the fact that when the power supply system needs to increase or decrease the voltage, the AC system only needs to add a transformer, and the technology and device in the DC system are much more complicated. Therefore, in addition to the special use of outdoor, in the photovoltaic power generation system need to be equipped with inverter. In addition, the inverter also has the function of automatic voltage regulation or manual voltage regulation, which can improve the power supply quality of the photovoltaic power generation system. Obviously, the inverter is an indispensable and important supporting equipment in the photovoltaic power generation system.
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