The photovoltaic power generation system is a device that directly converts solar energy into electrical energy. According to the relationship between the photovoltaic system and the grid, it can be divided into a photovoltaic system independent of the grid and a grid-connected system. A system that directly connects the photovoltaic cell to the load without an energy storage device in the middle is called a direct-coupled photovoltaic system. This type of system cannot provide energy during rainy days and at night, and a battery is usually added in between. Because the photovoltaic system is relatively affected by external factors, it is usually necessary to add a controller to adjust to obtain the rated power output, and add functions such as control and protection systems.
The photovoltaic power generation system basically includes four parts: photovoltaic panels, inverters, energy storage devices, and controllers. The energy storage devices generally use batteries, and most of them use lead-acid batteries in practical applications.
Introduction to the main functions of each part:
Solar cells-absorb solar energy and convert light energy into direct current electricity.
Controller-controls the depth of charge and discharge of the battery, and adjusts the inverter control signal as the load changes.
Storage battery--stores the electrical energy produced by solar panels and, when necessary, provides DC power to the load.
Inverter-converts DC power input into AC power output.
Compared with traditional large-scale power stations with high-voltage and long-distance transmission, the main advantages of independent power generation are: less investment, fast construction, reliable power supply, and low operating costs. An important advantage of a stand-alone power station is that it is close to users and does not require a high-voltage power transmission system, which can greatly reduce the investment in infrastructure. Furthermore, the site for installing small generators is easy to find, and the installation period is very short, which is also conducive to investment recovery. Since the transmission loss is much lower than that of the traditional power system, the operating cost of independent power generation is relatively low.
In terms of power supply reliability, the advantages of independent power generation are also obvious. High-voltage transmission and distribution facilities in traditional power systems are an important factor affecting the reliability of power supply. High-voltage lines and towers are severely damaged by natural disasters such as storms, ice and snow, and the loss can reach hundreds of billions of dollars, and some users have long-term power supply. Interrupted. Even in the summer when there are no natural disasters, there will be power outages caused by transmission line failures.
Solar photovoltaic power generation does not require any fuel, has no pollution to the environment, and is an ideal renewable clean energy. Photovoltaic power generation does not require a large area of land and can be installed on the roof or on the outer wall of a high-rise building. It is the easiest way to achieve independent power generation. There is neither any rotating mechanical device nor any chemical reaction device in the photovoltaic power generation equipment, and its management is simpler than other power generation methods.
Photovoltaic power generation is the direct conversion of solar radiation energy into electrical energy through the photovoltaic effect. Solar energy is unstable. The intensity of solar radiation in the same place is different at all times in the same day. The intensity of solar radiation at sunrise and sunset is far less than that before noon. The intensity of solar radiation is different in different seasons at the same location. For mid- and high-latitude regions, the intensity of solar radiation is significantly stronger in summer than in winter. Solar energy is also intermittent, and the direct solar radiant energy changes significantly with the alternation of day and night. Solar radiation is also greatly affected by factors such as climate, season, day and night. To make the power output of photovoltaic power generation stable, it is necessary to be equipped with energy storage devices. In addition, the output of solar cells and energy storage devices is direct current. To obtain alternating current, the photovoltaic power generation system needs to be equipped with a controller and inverter. The advantages of stand-alone photovoltaic power generation are summarized as follows:
1. Renewable, unlimited resources, can directly output high-grade electrical energy, with ideal sustainable development attributes;
2. No pollution, absolutely zero emissions—no emissions of any material and sound, light, electricity, magnetism, and mechanical noise;
3. Mobile and flexible, the power generation system can be integrated in modules as required, which can be large or small and easy to expand;
4. The universality of resources is basically not restricted by region, but there is a difference between rich and under-abundant regions;
5. Versatility and storability, electric energy can be easily transmitted, used and stored through transmission lines;
6. Resources, power generation, and electricity consumption are in the same area, which can greatly save the investment cost of remote power transmission and transformation equipment; the construction period of solar power generation system is short, because it is modularized, it can be used as small as a few milliwatts of solar power calculators. , Solar power stations of up to tens of megawatts; distributed power systems can improve the safety and reliability of the entire energy system, especially in remote areas and mountainous areas in China, where residents live very scattered and require long grid connections It is obviously an economical and effective method to use distributed power generation technology to supply power to residents.
Furthermore, solar photovoltaic power generation has its own unique characteristics:
1. No risk of exhaustion;
2. Absolutely clean (no pollution, outside the storage battery);
3. Not restricted by the geographical distribution of resources;
4. It can generate electricity near the place where the electricity is used;
5. High energy quality;
6. Users are easy to accept emotionally
7. It takes a short time to obtain energy;
8. The power supply system works reliably.
