Solar photovoltaic

Solar photovoltaic power generation system is a new type of power generation system that uses the photovoltaic effect of solar cell semiconductor materials to directly convert solar radiation energy into electrical energy. It has two modes of independent operation and grid-connected operation. Independently operating photovoltaic power generation systems need batteries as energy storage devices, which are mainly used in remote areas without power grids and scattered populations. The overall system cost is very high; in areas with public power grids, photovoltaic power generation systems are connected to the grid and run in parallel. The omission of batteries can not only greatly reduce the cost, but also has higher power generation efficiency and better environmental performance.
Overview:
Solar power generation is divided into solar thermal power generation and photovoltaic power generation. Generally speaking, solar power generation refers to solar photovoltaic power generation, referred to as "photovoltaic". Photovoltaic power generation is a technology that uses the photovoltaic effect of the semiconductor interface to directly convert light energy into electrical energy. The key element of this technology is the solar cell. After the solar cells are connected in series, they can be packaged and protected to form a large-area solar cell module, and then combined with power controllers and other components to form a photovoltaic power generation device.
Theoretically speaking, photovoltaic power generation technology can be used in any situation where power is needed, from spacecraft, down to household power sources, as large as megawatt power stations, as small as toys, and photovoltaic power sources are everywhere. The most basic components of solar photovoltaic power generation are solar cells (sheets), including monocrystalline silicon, polycrystalline silicon, amorphous silicon and thin-film batteries. Among them, single crystal and polycrystalline batteries are used the most, and amorphous batteries are used in some small systems and computer auxiliary power supplies. The efficiency of China's domestic crystalline silicon cells is about 10 to 13%, and the efficiency of similar products in the world is about 12 to 14%. Solar panels composed of one or more solar cells are called photovoltaic modules. Photovoltaic power generation products are mainly used in three aspects: one is to provide power for non-electricity occasions; the other is solar daily-use electronic products, such as various solar chargers, solar street lights and solar lawn lamps, etc.; third is grid-connected power generation. This has been widely implemented in developed countries. By 2009, China's grid-connected power generation has not yet begun to be fully promoted. However, part of the electricity used for the 2008 Beijing Olympics was provided by solar power and wind power.
It is predicted that solar photovoltaic power generation will occupy an important position in the world's energy consumption in the 21st century. It will not only replace some conventional energy sources, but also become the main body of the world's energy supply. It is estimated that by 2030, renewable energy will account for more than 30% of the total energy structure, and solar photovoltaic power generation will account for more than 10% of the world's total power supply; by 2040, renewable energy will account for more than 10% of the total power supply. More than 50% of the energy consumption, solar photovoltaic power generation will account for more than 20% of the total electricity; by the end of the 21st century, renewable energy will account for more than 80% of the energy structure, and solar power generation will account for more than 60%. These figures are sufficient to show the development prospects of the solar photovoltaic industry and its important strategic position in the energy field.
Taxonomy:
Photovoltaic power generation systems are divided into independent photovoltaic systems and grid-connected photovoltaic systems.
Independent photovoltaic power plants include power supply systems for villages in remote areas, solar household power systems, communication signal power supplies, cathodic protection, solar street lights, and other photovoltaic power generation systems with batteries that can operate independently.
Grid-connected photovoltaic power generation system is a photovoltaic power generation system that is connected to the grid and transmits power to the grid. It can be divided into grid-connected power generation systems with and without batteries. The grid-connected power generation system with storage battery is schedulable and can be merged into or out of the grid as needed. It also has the function of backup power supply, which can provide emergency power when the grid is out of power. Photovoltaic grid-connected power generation systems with batteries are often installed in residential buildings; grid-connected power generation systems without batteries do not have the functions of dispatchability and backup power, and are generally installed on larger systems.
Photovoltaic panels:
Photovoltaic panels are a kind of power generation device that collects heat when exposed to sunlight and converts light energy into direct current. It is composed of thin solid photovoltaic cells almost entirely made of semiconductor materials (such as silicon). Since there are no moving parts, it can be operated for a long time without causing any loss. Simple photovoltaic cells can provide energy for watches and computers, while more complex photovoltaic systems can provide lighting for houses and power the grid. Photovoltaic panel components can be made into different shapes, and the components can be connected to generate more electricity. Rooftops and building surfaces will use photovoltaic panel components, and even used as a part of windows, skylights or shading devices. These photovoltaic facilities are usually called photovoltaic systems attached to buildings.
Photovoltaic technology:
The sun is a natural source of energy. Every living creature on the earth has the ability to function, and even its survival, is due to the energy directly or indirectly from the sun. Our earth is almost 100 million miles away from the sun. The radiant energy it intercepts has been incredibly small, that is, about three ten millionths. Even such a small amount of energy is actually 100,000 times larger than the existing power generation capacity of the entire world! The world, especially the industrialized countries, began to feel energy shortages. Therefore, people began to turn to solar energy to solve the energy crisis.
Solar photovoltaic
Solar energy can be supplied unlimitedly every day, and the quantity is huge. If it is used in a large power plant, the greenhouse effect will be reduced. Some energy experts and environmental protection experts believe that the thermal impact of solar energy is much smaller than that of any other alternatives in meeting human energy needs in the future. As a new energy source that does not pollute the environment and is inexhaustible, it is everywhere. Especially in terms of power supply, some experts believe that solar power will eventually account for 20% of the power supply.
Solar energy is a kind of radiant energy. Solar power generation means that to directly convert sunlight into electrical energy, it must be converted into electrical energy with the help of an energy converter. The process of directly converting light energy into electrical energy is exactly called the photovoltaic effect. Without the help of any other mechanical parts, the energy in the light is obtained by the electrons of the semiconductor device, so electrical energy is generated. This kind of energy converter that converts light energy into electrical energy is a solar cell. Solar cells, like transistors, are made of semiconductors. Its main material is silicon, but there are also some other alloys. The high-purity silicon used in the manufacture of solar cells has to undergo a special purification process. As long as the solar cell is irradiated by sunlight or light, it can convert light energy into electrical energy, so that current flows from one side to the other, and generally can generate electricity equivalent to 10-20% of the received light energy. Generally speaking, the stronger the light, the more electricity is generated. In order to minimize the light reflection of the Solar Panel and convert light energy into electric energy, a layer of film that prevents light reflection is usually covered on it, making the surface of the solar panel purple. The basis of its working principle is the photovoltaic effect of the semiconductor PN junction. The so-called photovoltaic effect is when the object is illuminated, the charge distribution state in the object changes to produce an effect of electromotive force and current. When sunlight or other light illuminates the PN junction of the semiconductor, a voltage (called photo-generated voltage) appears on both sides of the PN junction. This phenomenon is the famous photovoltaic effect. Short-circuit the PN junction, and current will be generated.
The main advantage of solar power generation is that solar cells can be installed in spaces that are not normally used, such as the roof, without noise, have a long lifespan, and hardly need to be adjusted once they are installed. Now, as long as the roof is filled with solar cells, the self-sufficiency of electricity in the home can be achieved. Nowadays, the main use of solar energy is no longer small-scale, but professional in nature. It has played an important role from the military field, the communications field to the urban construction field. Venezuela has also launched cheap solar cars, and European scientists have developed lightweight solar cells that can be worn on the body. There is a huge room for development in the use of solar energy, and related technologies may achieve breakthroughs in a short period of time. It has been used by many developed countries as an important part of their energy strategy.
Principles of power generation:
Solar cells are devices that respond to light and can convert light energy into electricity. There are many kinds of materials that can produce photovoltaic effect, such as: single crystal silicon, polycrystalline silicon, amorphous silicon, gallium arsenide, indium copper selenium and so on. Their power generation principles are basically the same, and now take the crystal as an example to describe the process of photovoltaic power generation. P-type crystalline silicon can be doped with phosphorus to obtain N-type silicon, forming a P-N junction. When the light shines on the solar cell
Example of solar photovoltaic power generation system
On the surface, part of the photons are absorbed by the silicon material; the energy of the photons is transferred to the silicon atoms, causing the electrons to transition and become free electrons, which form a potential difference on both sides of the PN junction. When the circuit is connected externally, the voltage Under the action of, there will be current flowing through the external circuit to produce a certain output power. The essence of this process is: the process of converting photon energy into electrical energy.
Solar photovoltaic power calculation:
The solar AC power generation system is composed of solar panels, charge controllers, inverters and batteries; the solar DC power generation system does not include inverters. In order to enable the solar power generation system to provide sufficient power for the load, it is necessary to select various components reasonably according to the power of the electrical appliances. Take the 100W output power and use it for 6 hours a day as an example to introduce the calculation method:
1. First, calculate the number of watt hours consumed per day (including the loss of the inverter): if the conversion efficiency of the inverter is 90%, when the output power is 100W, the actual output power required should be 100W/90 %=111W; if it is used for 5 hours a day, the power consumption is 111W*5 hours=555Wh.
2. Calculate the solar panel: Calculate according to the effective daily sunshine time of 6 hours, and take into account the charging efficiency and the loss during the charging process, the output power of the solar panel should be 555Wh/6h/70%=130W. 70% of which is the actual power used by solar panels during charging
application:
In the 1960s, scientists already applied solar cells to space technology-power supply from communication satellites. At the end of the 20th century, in the process of continuous self-reflection on human beings, photovoltaic power generation, such a clean and direct form of energy, has become more and more important.
Solar photovoltaic system display
Kindness, not only in space applications, but also in many fields. Such as: Solar Garden Lights, solar power household systems, independent systems powered by villages, photovoltaic water pumps (drinking water or irrigation), communication power supplies, cathodic protection of oil pipelines, optical fiber communication pumping stations, seawater desalination systems, road signs in towns, and highways Highway road signs etc. Around the turn of the century, photovoltaic power generation in advanced countries such as Europe and the United States was integrated into the urban power system and the power supply system of natural villages in remote areas was included in the development direction. The combination of solar cells and building systems has formed an industrialization trend.
Application areas:
1. User solar power: (1) Small power supplies ranging from 10-100W, used for military and civilian life in remote areas without electricity, such as plateaus, islands, pastoral areas, border posts, etc., such as lighting, TV, radio cassette recorders, etc.; (2) 3 -5KW home roof grid-connected power generation system; (3) Photovoltaic water pump: solve the problem of drinking and irrigation in deep water wells in areas without electricity.
2. Traffic fields such as navigation lights, traffic/railway signal lights, traffic warning/sign lights, Yuxiang street lights, high-altitude obstruction lights, highway/railway wireless telephone booths, power supply for unattended road squads, etc.
3. Communication/communication field: solar unattended microwave relay station, fiber optic cable maintenance station, broadcasting/communication/paging power system; rural carrier telephone photovoltaic system, small communication machine, soldier GPS power supply, etc.
4. Petroleum, marine and meteorological fields: cathodic protection solar power systems for oil pipelines and reservoir gates, life and emergency power supplies for oil rigs, marine testing equipment, meteorological/hydrological observation equipment, etc.
5. Home lamp power supply: such as courtyard system, street lamp, portable lamp, climbing lamp, fishing lamp, black light lamp, rubber tapping lamp, energy-saving lamp, etc.
6. Photovoltaic power stations: 10KW-50MW independent photovoltaic power stations, wind-solar (diesel) complementary power stations, charging stations of various large parking plants, etc.
7. The combination of solar power generation and building materials in solar buildings will enable future large-scale buildings to achieve power self-sufficiency, which is a major development direction in the future.
8. Other fields include: (1) Supporting automobiles: solar cars/electric cars, battery charging equipment, car air conditioners, ventilators, cold drink boxes, etc.; (2) Solar hydrogen production and fuel cell regenerative power generation systems; (3) Sea water Desalination of equipment power supply; (4) Satellites, spacecraft, space solar power stations, etc.
related policy:
Notice of the National Development and Reform Commission on the Price Policy of Photovoltaic Power Generation Projects in 2018 (Fagai Price Regulations (2017) No. 2196
The Development and Reform Commissions, Price Bureaus, Energy Bureaus, Poverty Alleviation Offices of all provinces, autonomous regions, and municipalities directly under the Central Government, State Grid Corporation of China, China Southern Power Grid Corporation, and Inner Mongolia Electric Power Corporation:
In order to implement the requirements of the "Energy Development Strategic Action Plan (2014-2020)" of the General Office of the State Council on the gradual decline of new energy benchmark on-grid tariffs, rationally guide new energy investment, and promote the healthy and orderly development of the photovoltaic power generation industry, it was decided to adjust the 2018 photovoltaic power generation Benchmarking on-grid tariff policy. With business from the National Energy Administration, the relevant matters are hereby notified as follows:
1. In accordance with the current technological progress and cost reduction of the photovoltaic industry, reduce the benchmark on-grid power prices for photovoltaic power stations that will be put into operation after January 1, 2018. The benchmark on-grid tariffs for Type I, Type II, and Type III resource areas will be adjusted to 0.55 per kWh. Yuan, 0.65 yuan, 0.75 yuan (tax included). Starting from 2019, all photovoltaic power generation projects included in the annual scale management of fiscal subsidies will implement the corresponding benchmark electricity price according to the time of operation.
2. For distributed photovoltaic power generation projects that are put into operation after January 1, 2018 and adopt the mode of "self-generated and self-used, remaining online" mode, the subsidy standard for total electricity per kilowatt-hour will be reduced by 0.05 yuan, that is, the subsidy standard will be adjusted to 0.37 yuan per kilowatt hour (Including tax). Distributed photovoltaic power generation projects that adopt the "full online" mode are implemented at the price of photovoltaic power stations in the resource area. Distributed photovoltaic power generation projects are exempt from various government funds and surcharges collected with electricity prices, system reserve capacity fees and other related grid-connected service fees.
3. The benchmark electricity price of village-level photovoltaic poverty alleviation power stations (0.5 MW and below) and the subsidy standard for household distributed photovoltaic poverty alleviation projects remain unchanged.
4. All new energy power generation companies and power grid companies must truthfully and completely record and save relevant power generation project online transaction power, price and subsidy amount and other information, accept supervision and inspection by relevant departments, and submit relevant data to the National Renewable Energy Information Management Center. The price authorities at all levels should strengthen the supervision of the implementation of new energy on-grid tariffs and the settlement of additional tariff subsidies, and urge the implementation of relevant on-grid tariff policies.
5. Encourage local governments to carry out price reforms for nearby consumption of photovoltaic power generation and pilot market-based bidding pricing in accordance with relevant national regulations, and gradually improve the mechanism for discovering prices through the market.