- Development of China’s photovoltaic power generation industry
China is very rich in solar energy resources. Compared with other countries at the same latitude, it is similar to the United States and much superior to Europe and Japan, so it has huge development potential.
The research on solar cells in China began in 1958, and in 1959 the first solar cell with practical value was successfully developed. In March 1971, solar cells were successfully applied to China’s second artificial satellite for the first time. In 1973, it began to apply solar cells on the ground, and in 1979, it began to produce monocrystalline silicon solar cells. In the middle and late 1980s, foreign solar cell production lines or key equipment were introduced, and a solar photovoltaic industry with a production capacity of 4.5MW was initially formed. Among them, the monocrystalline silicon cell is 2.5MW, the amorphous silicon cell is 2MW, the conversion efficiency of the industrial module monocrystalline silicon cell is 11%~13%, and the amorphous silicon cell is 5%~6%. In the middle and late 1990s, the photovoltaic power generation industry entered a period of steady development, and the output of solar cells and modules increased steadily year by year. After more than 30 years of hard work, China’s photovoltaic power generation industry has ushered in a new stage of rapid development in the early 21st century.
The production of photovoltaic modules in China is increasing year by year, the cost is decreasing, the market is expanding, and the installed capacity is increasing year by year. Application areas include rural electrification, transportation, communication, petroleum, meteorology, national defense, etc. In particular, the independent solar photovoltaic power generation system solves the electricity consumption of schools, medical centers, household lighting, and televisions in many remote areas, and plays a very important role in the development of social economy and culture in remote and poor areas. Seven counties without electricity in Tibet use solar photovoltaic power plants for power supply, and the social and economic benefits are very significant.
In terms of research and development, China has carried out research on monocrystalline silicon and polycrystalline silicon cells and thin film cells such as amorphous silicon, cadmium telluride, and copper selenium. And gratifying results have been achieved, among which the efficiency of grooved buried gate cells has reached the international level. China’s photovoltaic industry has formed a good foundation, but there is still a big gap between China and foreign countries in the overall level, mainly in the following aspects.
(1) The production scale is small. The production capacity of Chinese solar cell manufacturing plants is about 0.5~1 MW/a, which is more than an order of magnitude lower than the foreign production scale.
(2) The technical level is low. There is a certain gap between the photoelectric conversion efficiency and packaging level of solar cells compared with foreign countries. The supporting technology of solar photovoltaic power generation system is not yet mature. For example, grid-connected inverters and controllers have not yet achieved independent R&D and commercial production, and the product reliability is low, mainly relying on imports; the battery technology in independent solar photovoltaic power generation systems is not yet up to standard, and the service life is low.
(3) The localization of special raw materials has achieved certain results after years of research and development, but the performance still needs to be further improved, and some materials still rely on imports, such as a serious shortage of high-purity silicon materials (95% rely on imports).
(4) High cost. The cost and selling price are higher than foreign products (the initial investment of independent solar photovoltaic power generation system is 80,000~100,000 yuan/kW, the investment of grid-connected solar photovoltaic power generation system is 60,000~80,000 yuan/kW, and the power generation cost is 3.5~5 yuan/kWh. kW h), the development of the commercialization market of photovoltaic power generation systems is limited.
(5) Slow market cultivation and development, lack of supporting policies, regulations and measures for market cultivation and development.
(6) China’s solar cell production capacity is rapidly increasing. If the production scale is expanded blindly, there may be a crisis of overcapacity. The main market for domestic solar cells is currently abroad (more than 95% are exported).
The development of China’s photovoltaic industry has experienced two jumps. The first time was in the late 1980s, when China’s reform and opening up was in a period of vigorous development. China successively introduced a number of solar cell production lines, increasing China’s solar cell production capacity from the original three small factories of several hundred kW. Up to 4.5MW of the 6 plants, the investment in the imported solar cell production equipment and production lines mainly comes from the central government, local governments, national industrial ministries and large national enterprises. The second major development of the photovoltaic industry after 2000 was mainly influenced by the international environment, the launch of international projects, government projects and the pull of the market. In 2002, the “Guangming Project” pilot project and the “Power Transmission to the Township” project implemented by the National Development and Reform Commission, as well as the power transmission to the village project implemented in 2006, all adopted solar photovoltaic power generation technology. Driven by these measures, the momentum of rapid development of China’s solar photovoltaic power generation industry has become increasingly clear.
At the end of 2007, the cumulative installed capacity of China’s solar photovoltaic power generation system reached 100 MW, and there were more than 50 companies engaged in solar cell production. The annual output of solar cells reached 1,188 MW, surpassing Japan and Europe. The complete industrial chain composed of multiple links such as system construction, especially the production of polysilicon materials, has made significant progress, breaking through the annual output of 1,000 tons, breaking through the bottleneck restriction of the production of solar cell raw materials, and making great progress in the large-scale development of photovoltaic power generation in China. established the foundation. 2007 was a year of rapid development of China’s solar photovoltaic industry. Benefiting from the long-term benefits of the solar energy industry, the entire photovoltaic industry experienced an unprecedented investment boom.
According to the “Medium and Long-Term Development Plan for Renewable Energy”, in 2020, China strives to increase the installed capacity of solar power generation to 1.8 GW, and in 2050 it will reach 600 GW. It is estimated that in 2050, the installed capacity of renewable energy in China will account for 25% of the installed capacity of the country, of which the installed capacity of photovoltaic power generation will account for 5%.
- Application of solar photovoltaic power generation
Harnessing electricity from solar energy has become the world’s fastest-growing form of energy supply, according to the Worldwatch Institute in its latest research report. According to the report, since 1990, the global market sales of solar photovoltaic power generation devices have increased by an average annual rate of 16%, and the current total power generation capacity has reached 800MW. With the decline in the cost of solar photovoltaic power generation, photovoltaic power generation is gradually expanding its application fields, and it is currently mainly used in the following four aspects.
(1) Consumer products, such as calculators powered by amorphous silicon solar cells, solar clocks, solar lighting, solar radios, televisions, etc. These products account for about 14% of the world’s photovoltaic product sales.
(2) Residential power supply systems far from the grid, including household decentralized power supply and centralized power supply of independent solar photovoltaic power stations, which account for 35% of the world’s photovoltaic product sales.
(3) Off-grid industrial power supply system, which accounts for 33% of the world’s photovoltaic product sales.
(4) Grid-connected solar photovoltaic power generation system, which accounts for 18% of the world’s photovoltaic product sales.
- The development trend and prospect of solar photovoltaic power generation
The development of new energy and renewable clean energy is one of the five technical fields with the most decisive influence in the world economic development in the 21st century. The full development and utilization of solar energy is the energy strategy decision of governments around the world for sustainable development, of which solar photovoltaic power generation has attracted the most attention. Solar photovoltaic power generation will be applied on a large scale in the long term, and can meet the needs of special application fields in the near future.
Since the 1990s, driven by sustainable development strategies, renewable energy technology has entered a stage of rapid development. Experts predict that by the middle of the 21st century solar energy and other renewable energy sources could provide 50% of the world’s energy consumption. The perfect combination of solar photovoltaic power generation systems and buildings embodies an ideal example of sustainable development, and the international community attaches great importance to it. The International Energy Organization (IEA) launched the building photovoltaic integration plan twice in 1991 and 1997, and achieved great success. Building photovoltaic integration has the following advantages.
(1) It has the characteristics of high technology, no pollution and self-power supply, which can strengthen the beauty and construction quality of the building.
(2) Photovoltaic components are part of the overall composition of the building. In addition to the power generation function, they are also the weather-resistant external protective layer of the building, which has the characteristics of multi-function and sustainable development.
(3) Distributed solar photovoltaic power generation and distributed buildings can be matched with each other.
(4) The outer wall of the building can provide enough area for the photovoltaic system.
(5) No additional floor space is required, the support structure of the photovoltaic system is omitted, and the cost of power transmission is omitted; PV arrays can replace conventional building materials, thereby saving installation and material costs, such as expensive exterior wall cladding and decoration The cost may be equal to the cost of the photovoltaic module, and if the photovoltaic power generation system is integrated into the building construction process, the installation cost can be greatly reduced. The building photovoltaic integrated system is suitable for both residential houses, commercial, industrial and public buildings, highway sound barriers, etc.; it can be integrated into the roof and the outer wall; it can be integrated into the newly designed buildings, It can also be integrated into existing buildings. Photovoltaic building integration has developed rapidly in recent years, and many countries have successively formulated their own photovoltaic roof plans. The building’s own energy consumption accounts for 1/3 of the world’s total energy consumption, making it the largest market for the future solar photovoltaic power generation industry. The combination of photovoltaic power generation system and building will fundamentally change the subordinate position of solar photovoltaic power generation in the world energy, and the prospect is bright.
Experts predict that in the first half of the 21st century, photovoltaic power generation will exceed nuclear power generation in 30 to 50 years. Calculated in 2040, this requires an annual growth rate of photovoltaic power generation of 16.5%, which is a very realistic development rate, provided that the installation cost of photovoltaic systems is at least comparable to that of nuclear power generation.
The main obstacle affecting the large-scale application of solar photovoltaic power generation at present is its high manufacturing cost. Among many power generation technologies, solar photovoltaic power generation is still the one with the highest cost. Therefore, the main goal of developing solar photovoltaic power generation technology is to improve the current Some manufacturing processes, designing new battery structures, and developing novel battery materials can reduce manufacturing costs and improve the photoelectric conversion efficiency of solar cells. In recent years, the photovoltaic industry has shown a trend of stable development, which is characterized by increased output, improved conversion efficiency, reduced cost, and expanding application fields.
Recently, the Swiss Federal Institute of Technology developed a titanium dioxide solar cell with a photoelectric conversion rate as high as 33%, and successfully used an amorphous organic material instead of the electrolyte, making it less expensive than a piece of glass about the same size Much easier to use. It can be expected that with the advancement of technology and the expansion of the market, the cost and selling price of solar cells will drop significantly. With the decline in the cost of solar cells, solar photovoltaic power generation technology will enter a period of large-scale development.
In recent years, photovoltaic technology has developed rapidly and rapidly, focusing on issues such as photovoltaic cell materials, conversion efficiency and stability. The research focus of crystalline silicon solar cells is high-efficiency monocrystalline silicon cells and low-cost polycrystalline silicon cells. The main technical obstacles that limit the photoelectric conversion efficiency of monocrystalline silicon solar cells are:
(1) The shading effect of grid lines on the battery surface.
(2) Surface light reflection loss.
(3) Optical conduction loss.
(4) Internal compound loss.
(5) Surface recombination loss.
In response to these problems, many new technologies have been developed in recent years, mainly including:
(1) Single and double layer reflective film technology.
(2) Laser groove buried gate line technology.
(3) Suede technology.
(4) Back point contact electrode technology.
(5) High-efficiency back reflector technology.
(6) Light absorption technology.
With the application of these new technologies, many new types of solar cells have been invented, which greatly improves the photoelectric conversion efficiency of solar cells. For example, Professor Green of the University of New South Wales in Australia has used new technologies such as laser groove buried grid lines to increase the photoelectric conversion efficiency of high-purity crystalline silicon solar cells to 24.4%. Another feature of the development of photovoltaic power generation technology is the significant progress made in the research field of thin-film solar cells and the continuous emergence of various new types of solar cells. Although the photoelectric conversion efficiency of crystalline silicon solar cells is high, it is difficult to greatly reduce the cost, while thin-film solar cells have a very broad and attractive prospect in reducing the manufacturing cost. As early as a few years ago, Australian scientists have used low-quality silicon materials with a multilayer thin film structure to reduce the cost of solar cells by 80%. To this end, the Australian government invested 64 million US dollars to support this research, and hopes to make the project within 10 years. Technology commercialization.
In the late 1990s, solar photovoltaic power generation developed more rapidly. In terms of industry, countries have been reducing costs through measures such as expanding scale, increasing automation, improving technology, and opening up markets, and have made great progress.
In terms of research and development, the efficiency of monocrystalline silicon cells has reached 24.7%, and the efficiency of polycrystalline silicon cells has exceeded 19.8%. Amorphous silicon thin film cells have made new breakthroughs in overcoming light attenuation and improving efficiency through double junction, triple junction stacking and alloy layer technology, and the laboratory stable efficiency has exceeded 15%. The efficiency of the crushing pot battery reached 15.8%, and the efficiency of the copper indium selenide battery reached 18.8%. Since 1987, the research work of crystalline silicon thin film battery has developed rapidly and has become a new hot spot of the world’s attention.
The development of photovoltaic power generation in the world in the 21st century will have the following characteristics.
(1) The photovoltaic industry will continue to develop at a high growth rate. Over the years, the photovoltaic industry has been one of the fastest and most stable fields in the world. It is predicted that the production of photovoltaic modules will develop at an increasing rate of 20% to 30% or even higher in the next 10 years. The future prospects of photovoltaic power generation have been recognized by more and more national governments and financial circles (such as the World Bank), and many developed countries and regions have formulated photovoltaic power generation development plans. It is expected that by the middle of the 21st century, solar photovoltaic power generation will become one of the basic energy sources for mankind.
(2) The cost of solar cell modules will be greatly reduced. The installation cost of solar photovoltaic power generation systems is decreasing at a rate of 9% per year. Cost reduction can be achieved through technological approaches such as scaling up, increasing automation and technology, and improving battery efficiency. Considering that there will be major breakthroughs in thin-film solar cell technology in the 21st century, the potential for cost reduction is even greater. Therefore, it is an inevitable trend to greatly reduce the cost of solar cell modules in the 21st century.
(3) The solar photovoltaic power generation industry will develop to a scale of 100 megawatts. At the same time, the degree of automation and technical level will also be greatly improved, and the battery efficiency will develop to a higher level.
(4) A breakthrough will be made in thin-film solar cell technology. Thin-film solar cells have the potential to greatly reduce costs, and many countries in the world are vigorously researching and developing thin-film solar cells. In the 21st century, the technology of thin-film solar cells will achieve a major breakthrough, the scale will be developed to above 100 megawatts, the cost will be greatly reduced, and the goal of solar photovoltaic power generation to compete with conventional power generation will be achieved, thus becoming an alternative energy source.
(5) The rapid development of solar photovoltaic building integrated grid-connected power generation. Building photovoltaic integration has the characteristics of multi-function and sustainable development. The design of building photovoltaic integration makes the building cleaner, more perfect, pleasing to the eye and easy to be accepted by professional architects, users and the public. The perfect combination of solar photovoltaic power generation systems and buildings embodies an ideal example of sustainable development, and the international community attaches great importance to it. Many countries have successively formulated their own roof plans, making the building photovoltaic integration technology flourish. The combination of photovoltaic power generation systems and buildings will make the transition of solar photovoltaic power generation to alternative energy sources and become an important part of the world’s energy structure.