With the continuous development of the global economy and society, energy consumption has also continued to grow accordingly. The energy issue has become the primary issue related to human survival and development. In recent years, the utilization of solar energy has gradually become a highly developed and widely used energy source in the field of new energy, especially in remote areas far from the power grid. Mainly analyzed and studied the solar photovoltaic grid connected power generation system. The paper first introduces the characteristics and basic principles of solar power generation systems, and provides a detailed analysis of the functions of each component of the system. Next, research will be conducted on the inverter, which is the most important part of solar photovoltaic grid connection. Once again, propose a design scheme for a solar photovoltaic grid connected power generation system. Finally, design the hardware of the solar photovoltaic grid connected power generation system. Grid connected solar photovoltaic power generation fully leverages the advantages of new energy and can alleviate energy shortages, which is an inevitable direction for the large-scale development of solar energy. The Chinese government attaches great importance to solar photovoltaic grid connected power generation and gradually promotes the “Roof Plan”. Solar grid connected power generation is moving from supplementary energy to alternative energy.
1. Introduction to solar photovoltaic power generation
Solar photovoltaic power generation is a power generation method that utilizes the photovoltaic effect to convert solar radiation into electrical energy, and is the mainstream of solar power generation today. Solar power generation is a power generation method that directly converts light energy into electrical energy without the need for thermal processes. It includes solar photovoltaic power generation, photochemical power generation, photoinduced power generation, and photobiological power generation.
2.Categories of solar photovoltaic power generation systems
Solar power generation systems can be divided into two categories: independent systems and system connection systems (also known as AC grid connection systems). Independent systems are the most basic form of solar power generation systems, also known as the prototype system of solar power generation. This type of system is often used as a power supply for offshore lighthouses, buoys, and wireless relay stations located far from the city center (unmanned). The DC power output from the solar cell array directly supplies the load. If the load is AC, then DC power must also be converted into AC power through an inverter. In addition, the output DC energy is also used to charge the battery. Due to frequent fluctuations in the voltage of the load, a controller should also be set up to regulate the voltage. In terms of power system terminology, it is called “reverse flow” operation or colloquially referred to as “selling electricity”. On the contrary, for power companies, normal operation is to supply power to users, which is called “positive trend”. The advantage of a system connected solar power generation system is that when there is insufficient solar power generation during rainy weather or at night, it can be directly purchased from the municipal power grid through system connection. Another important advantage of the system connection system is that it can eliminate batteries, reduce costs, and enhance the stability and reliability of power supply.
3. Power generation methods of solar photovoltaic power generation systems
There are two ways of solar power generation: one is the light heat electricity conversion method, and the other is the direct light electricity conversion method.
3.1 The light heat electricity conversion method utilizes the thermal energy generated by solar radiation to generate electricity. Generally, the absorbed thermal energy is converted into working fluid steam by a solar collector, which then drives a steam turbine to generate electricity. The previous process is the photothermal conversion process; The latter process is the thermal electrical conversion process, similar to ordinary thermal power generation.
3.2 Direct Photoelectric Conversion Method This method utilizes the photoelectric effect to directly convert solar radiation energy into electrical energy. The basic device for photoelectric conversion is solar cells. A solar cell is a device that directly converts solar energy into electrical energy due to the photovoltaic effect. It is a semiconductor photodiode that, when sunlight shines on the photodiode, converts the solar energy into electrical energy and generates current. When many batteries are connected in series or parallel, they can become a solar cell array with relatively high output power.
4. Main factors affecting solar photovoltaic power generation
The utilization of solar energy mainly relies on the solar radiation reaching the ground. Solar radiation can be divided into two types. One type is light radiation emitted from the surface of the photosphere, which is also called electromagnetic wave radiation because it propagates light and heat in the form of electromagnetic waves. This radiation is composed of visible and invisible light. Another type is particle radiation, which is a stream of particles composed of positively charged protons, approximately equal amounts of negatively charged electrons, and other particles. Particle radiation is usually weak and energy is unstable, and it is strongest during the solar maximum period. It has a certain impact on humans and the Earth’s upper atmosphere, but generally, it gradually disappears on the long distance between the sun and the Earth before it radiates to the surface of the Earth. Therefore, solar radiation is mainly light radiation. Due to the presence of the atmosphere, the amount of solar radiation energy that truly reaches the Earth’s surface is influenced by various factors. Generally speaking, solar height, atmospheric quality, atmospheric transparency, geographic latitude, sunshine duration, and altitude are the main influencing factors.
5. Composition of grid connected solar photovoltaic power generation system
The solar photovoltaic system consists of the following three parts: solar cell modules; Power electronic equipment such as charging and discharging controllers, inverters, testing instruments, and computer monitoring, as well as batteries or other energy storage and auxiliary power generation equipment.
Solar photovoltaic systems have the following characteristics: (1) no rotating parts, no noise generation; (2) No air pollution, no discharge of wastewater; (3) No combustion process, no fuel required; (4) Simple maintenance and low maintenance costs; Solar photovoltaic systems are widely used, and their basic forms can be divided into two categories: independent power generation systems and grid connected power generation systems. The main application areas are in spacecraft, communication systems, microwave relay stations, television turntables, solar photovoltaic water pumps, and household power supply in areas with no or no electricity.
6. Development and Prospects
Since the 1990s, it has been a period of rapid development for solar photovoltaic power generation in China. During this period, China’s solar photovoltaic module production capacity has been increasing year by year, costs have been continuously decreasing, the market has been expanding, and installed capacity has been increasing year by year. In 2006, the cumulative installed capacity reached 35MW, accounting for about 3% of the world share. Over the past decade, China’s solar photovoltaic industry has maintained an average global market share of about 1% on a long-term basis. By 2020, China’s photovoltaic technology industry will continue to improve and develop, with costs decreasing and the solar photovoltaic market undergoing significant changes. It is expected that from 2005 to 2010, China’s solar cells will mainly be used for independent solar photovoltaic power generation systems, and the power generation cost will be approximately 1.20 yuan/kWh by 2010; From 2010 to 2020, solar photovoltaic power generation will shift from independent systems to grid connected power generation systems, with a power generation cost of approximately 0.60 yuan/kWh by 2020. The technological level of China’s solar photovoltaic industry is expected to reach the world’s advanced level by 2020. At present, the world’s solar photovoltaic power generation industry is still in its early stages. In order to ensure the healthy development of the solar photovoltaic power generation industry, it is necessary to do the following work: (1) develop a maximum power tracking algorithm for solar photovoltaic cells to achieve maximum solar power tracking; (2) Develop optimization and combination algorithms for solar photovoltaic arrays to achieve optimal combination of solar photovoltaic cell arrays.
With the continuous increase in energy consumption worldwide, the environmental pollution caused by the abuse of fossil fuels is becoming increasingly serious. While addressing the sustained economic development, humans also need to focus on the issue of ecological balance. Human exploration and research on solar energy utilization will become more active, and it also indicates that solar photovoltaic grid connected power generation will play an increasingly important role in future society.