(1) Solar panels: Solar panels are the core and most valuable part of solar power generation system. Its function is to convert the radiation ability of the sun into electric energy, or send it to the storage battery for storage, or push the load to work. The quality and cost of solar panels will directly determine the quality and cost of the whole system;
(2) Solar controller: The function of the solar controller is to control the working state of the whole system and protect the battery from overcharge and overdischarge. In places with large temperature difference, qualified controllers should also have temperature compensation function. Other additional functions, such as light control switch and time control switch, should be optional for the controller;
(3) Battery: generally lead-acid battery. In small and micro systems, nickel-hydrogen batteries, nickel-cadmium batteries or lithium batteries can also be used. Its function is to store the electric energy generated by solar panels when there is light, and then release it when needed.
(4) Inverter: 220VAC, 1 10VAC AC power supply is required in many occasions. Because the direct output of solar energy is generally 12VDC, 24VDC and 48VDC. In order to provide electrical energy for 220VAC appliances, DC energy generated by solar power generation system needs to be converted into AC energy, so DC- AC inverter is needed. In some cases, DC-DC inverter is also used when loads with multiple voltages are needed, such as converting 24VDC to 5VDC (note that it is not a simple step-down).
The design of solar power generation system needs to consider the following factors:
Q 1。 Where is the solar power generation system used? What is the solar radiation situation in this area?
Q2。 What is the load power of the system?
Q3。 What is the output voltage of the system, DC or AC?
Q4。 How many hours does the system need to work every day?
Q5。 How many days does the system need continuous power supply in rainy days without sunshine?
Q6。 What is the load, pure resistance, capacitance or inductance, and what is the starting current?
Q7。 Quantity required by the system.
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Solar power generation: actually, it is not expensive.
Prompt in this issue
Dr. Shi, general manager of Wuxi Suntech Solar Power Generation Co., Ltd., has studied and worked in Australia for 14 years. His sole purpose in returning to China to start a business is to develop the solar energy industry in China. He said: "There is a misunderstanding in society that the cost of solar power generation is higher every time. In my opinion, if calculated by the standards of environmental protection and sustainable development, compared with thermal power,
Solar power is not expensive. If the country makes a decisive decision and introduces industrial policies to encourage the development of green energy, with the progress of technology, the cost of solar power generation will be further reduced. His remarks aroused the curiosity of journalists, who interviewed many experts and asked them to discuss with them what should be done to make solar power generation benefit human beings and the environment as much as possible.
Industrial application absorbs R&D cost.
Ma, a researcher at the Institute of Electrical Engineering of China Academy of Sciences, said that a new technology has different application requirements at different stages of development. Compared with other renewable energy power generation technologies, photovoltaic power generation has outstanding technical and economic advantages in solving the power supply problem of scattered villages and farmers and herdsmen in remote areas, and will play an important role in solving the power supply problem of 30 million people far from the power grid in China. In some special fields, photovoltaic power generation has risen rapidly, showing "comparative advantages" in many fields such as aerospace power supply, unattended power supply for communication stations, pipeline cathodic protection, military field power supply, toys, clocks and watches, street lamps, courtyard lights and recently emerging environmental protection buildings. Industrial application can absorb a lot of research costs, and then promote the in-depth technical research, find more suitable materials and reduce cost solutions.
Huang Ming Solar Group initially focused on photothermal business, and its solar vacuum tube water heater ranked first in China. Huang Ming, the company's president, said, "We are also considering marching in the photoelectric direction recently. We started the business of "solar lighting" in Rizhao City, Shandong Province, and made a model project. I believe that as long as the industrial incentive policy is clear, the cost of solar power generation will drop rapidly under the impetus of application. " Meng Xiang 'an, secretary general of China Solar Energy Society, said that China is one of the countries rich in solar energy resources. China's desert covers an area of 6.5438+0.08 million square kilometers, which is mainly distributed in the northwest region rich in light energy resources. 100 MW photovoltaic array can be installed in an area of 1 km2, and can generate electricity10.50 billion kwh per year; If 1% desert is developed and utilized, it can generate electricity consumption equivalent to the whole year of China in 2003. There is a vast desert around the main power line in China, which is suitable for large-scale installation and development of photovoltaic power generation. It is of far-reaching strategic significance to develop and utilize desert solar energy resources in China. It is also a very important way to learn from the experience of Europe and Japan and implement rooftop photovoltaic projects.
Wuxi Suntech Company has spent a lot of energy on "user training", and they have spent a lot of energy on integrating and stimulating the industrial chain. The annual meeting of the company is actually a passionate collision between upstream and downstream manufacturers in the solar cell industry. Ji, deputy general manager of the company, said: "We are preparing to train architects, real estate developers and government officials in solar energy. As long as we spend some energy and have a little understanding of the principle and industrial prospect of solar power generation, there will be no doubt about the prospect and necessity of this industry. Moreover, our company is also preparing to invest in the upstream silicon wafer industry, which can not only ensure sufficient and stable production raw materials in the future, but also reduce costs to a certain extent. "
Technological progress promotes cost reduction.
In the past, the materials of solar cells were all silicon, but the domestic production capacity of silicon wafers was still too low, and most of the materials were imported, which led to the high cost of solar cells. To promote solar power generation on a large scale, scientists must reduce the cost of solar cell materials or find cheaper solar cell materials.
Zhao Yuwen, director of the Photovoltaic Professional Committee of China Solar Energy Society, said that the current price of solar cells is about 3. 15 USD/watt, the price of grid-connected system is 6 USD/watt, and the power generation cost is 0.25 USD/watt. The preliminary study on the recently built 8 MW grid-connected photovoltaic system shows that the on-grid electricity price of fully commercialized grid-connected photovoltaic power generation is about 3.4 yuan/kWh, which cannot compete with thermal power and wind power. However, recent large-scale market development and rapid technological progress around the world are effectively reducing the cost of photovoltaic system equipment and power generation. It is predicted that by 20 10, the photovoltaic system will be reduced to about 3 USD/watt, and the power generation cost will be reduced to about 0. 1 USD/kwh, which is about RMB 1 yuan. He said: "At present, the cost of thermal power is rising day by day, and it is timely to develop solar power generation."
Shi said: "Scientists all over the world have racked their brains to find technical solutions to reduce costs. Diversified directions. The most conventional way is to find and organize new materials to improve photoelectric conversion efficiency. Some people look at 15% and 17% and think that the efficiency is' incredibly low'. In fact, as long as the cost increases by one percentage point, the cost will be greatly reduced and the competitiveness will be improved. Our Wuxi Suntech Company is conducting this research. "
Li Jinmin, director of the Semiconductor Research Institute of the Chinese Academy of Sciences, revealed that the Institute has also made a major breakthrough in solar cell research recently. They have greatly improved the photoelectric conversion efficiency by using some "chemical semiconductor" materials. In addition, after careful integration, the conversion efficiency of the whole system can reach 26% in the simulated space environment, and can exceed 30% in the ground environment. In this way, the cost is not a problem.
Changing ideas is a top priority.
Several solar energy experts have recently drafted a proposal on setting the ladder price and promoting the development of photovoltaic power generation in China. Wang Si Cheng, one of the drafters and executive director of the Photovoltaic Professional Committee of China Solar Energy Society, said: "From the perspective of quantity, universality of distribution and reliability of technology, photovoltaic power generation is superior to other renewable energy sources. At present, high-cost obstacles are decreasing with technological progress and mass production. There is no doubt that photovoltaic power generation will become an important part of future electricity. " Experts suggest that the goal of China should be to make the cumulative installed capacity of photovoltaic power generation reach 30,000 MW in 2020, so that the photovoltaic power generation will reach 1% of the national power generation by then.
Although there is still a big gap between this indicator and the goal of Europe, America and Japan, many obstacles must be removed to achieve this goal. Experts pointed out that in many countries in the world, photovoltaic power generation has entered the track of commercial development; It has a good long-term development prospect in the field of large-scale grid-connected desert and photovoltaic building integration, and is an important part of renewable energy application. In recent years, the global photovoltaic power generation industry has grown rapidly at an average rate of more than 30%, and the system output value reached more than 3.5 billion US dollars in 2002. It is expected that the industrial development will be further accelerated with the promotion of emission reduction actions and preferential policies in various countries. As long as China issues corresponding policies, cultivates standardized scale markets, increases investment and speeds up capacity building, China enterprises are fully qualified to rely on the domestic market to advance into the international market and enter the top ten in the world.
Zhao Yuwen said: "But the premise of its development is that the government introduces effective incentive policies. In recent years, the fact that the photovoltaic industry in Germany, Japan, the United States and other developed countries has developed rapidly proves that the government's policies and strategies of adopting preferential policies to support the photovoltaic power generation market, relying on the scale market to promote industrial development and technological progress, relying on technological progress and scale production to reduce production costs, and winning a larger market by improving quality and lowering prices are correct and successful, which is worth learning from in China. "
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Solar power generation has great potential, and the solar cell industry will make great achievements.
In the solar power generation system, the most technically complex component should be the solar cell. It can be said that solar cell is the core of solar power generation system, and its research and production directly affect the popularization and development of solar power generation.
The main principle of solar cells is to place a thinner N-type semiconductor on a thicker P-type semiconductor by using semiconductor materials. When photons hit the device surface, electrons diffuse at the junction of P-type and N-type semiconductors to generate current, which can be extracted and utilized by using metal conductors at the upper and lower ends.
Types of solar cells According to the different materials used, solar cells can be divided into: 1, silicon solar cells; 2. Batteries made of inorganic salts, such as gallium arsenide III-V compounds, cadmium sulfide, copper indium selenium and other multicomponent compounds; 3. Solar cells made of functional polymer materials; 4. Nanocrystalline solar cells, etc.
Silicon is the most ideal material for solar cells, which is also the main reason why solar cells mainly use silicon. Among the above batteries, monocrystalline silicon solar cells have the highest conversion efficiency and the most mature technology, and the photoelectric conversion efficiency can reach 23.3%. In the manufacturing process, surface texturing, emitter passivation, partition doping and other technologies are generally used. However, due to the influence of the material price of monocrystalline silicon and the corresponding complex process, the cost price of monocrystalline silicon remains high, so it is difficult to greatly reduce the cost and realize the large-scale popularization of solar power generation.
With the continuous development of new materials and related technologies, solar cells based on other materials are showing more and more attractive prospects. At present, the research of international low-cost mass production technology mainly focuses on the manufacturing technologies such as polysilicon, large-area thin-film amorphous silicon, CdTe battery and CIS battery, III-V compound semiconductor high-efficiency photovoltaic battery, amorphous silicon and crystalline silicon mixed thin-film photovoltaic battery.
If the characteristics of monocrystalline silicon are high efficiency and high cost, then the problems of other materials batteries are undoubtedly low cost and weak conversion. Compared with monocrystalline silicon solar cells, except polycrystalline silicon and cadmium telluride, the photoelectric conversion efficiency of other materials is generally less than 15%.
The development of solar cells in China 1958 began to study solar cells, and 197 1 was first applied to satellites launched by China. 1973, solar cells were used on the ground. Due to the limitation of price and output, the market development is very slow. In addition to being used as a satellite power supply, solar cells are only used in low-power power supply systems on the ground, such as navigation lights and railway signal systems.
In 2002, the relevant ministries and commissions of the state launched the "plan to electrify villages without electricity in western China" to solve the problem of electricity consumption in villages without electricity in seven western provinces through photovoltaic and small-scale wind power generation. The start of this project has greatly stimulated the solar power generation industry, and a number of solar cell packaging lines have been built in China, which has rapidly increased the annual output of solar cells.
At present, solar cells have been widely used in communication, transportation, civil products and other fields. Photovoltaic power generation is not only included in the national key research plan, but also included in the national power construction plan, and has also been applied in some major engineering projects. At present, photovoltaic power generation has spread all over the western provinces of China and some provinces, cities and autonomous regions in the central and eastern regions, with a total investment of more than 3 billion yuan.
The unification of high efficiency and low price of solar cells has always been the goal of international development. Similarly, the fundamental problem of product production and promotion in China is also concentrated here. There is a huge demand in areas without electricity such as grasslands, islands and deserts, but problems such as price affordability, insufficient production scale and weak product pertinence are very prominent. In urban power system, the high one-time investment cost undoubtedly increases the difficulty of product promotion. Therefore, improving efficiency, reducing cost and expanding scale should be the theme of developing and producing solar cells today.
In concrete operation, the research of polysilicon solar cells should combine tackling key problems with introduction, and establish a production line with an annual output of megawatts as soon as possible; Monocrystalline silicon solar cells focus on improving module efficiency and reducing production costs; Accelerate the development of new solar cells. Specific standards: the main technical and economic indicators of establishing a megawatt polysilicon solar cell module production line: module efficiency 13%, module life of 20 ~ 25 years; The main technical and economic indexes of technological transformation of monocrystalline silicon solar cell module production line are: module efficiency 14% ~ 15%, module life 20 ~ 25 years.
In order to develop rapidly under the existing technical conditions, the solar cell industry should realize the industrialization of small optical power supply as soon as possible; Focus on the development of serialization, standardization and commercialization of independent photovoltaic power stations below 100 kW, and study the grid-connected photovoltaic power generation technology to prepare for large-scale application.
Specific standards: industrial power range of low-power photovoltaic power supply: kilowatt class and 100-watt class industrial scale: total capacity is greater than1MW; The system cost is 30% lower than the average price in the Eighth Five-Year Plan. Serialization, standardization and commercialization of independently operated photovoltaic power plants. Power range: 10 kW ~ 100 kW system cost: 30% lower than the average price in the eighth five-year plan; Research and demonstration of photovoltaic grid-connected power generation technology. Preliminary study of megawatt grid-connected photovoltaic power station, development of 10 kW grid-connected photovoltaic demonstration power station and 100 kW grid-connected photovoltaic power station inverter, photovoltaic power station operation and related technology research of power system.
Using solar photovoltaic power generation is an irreversible trend of energy utilization. China has become the second largest electricity market in the world after the United States, and the demand growth rate is the first in the world. However, the shortage of oil and coal resources makes the existing power generation methods far from meeting the demand for electricity, and the promotion of solar power generation is quite urgent, with huge market potential. Aiming at the market and speeding up the development, the solar cell industry is bound to have great potential.