According to records, mankind has used solar energy for more than 3,000 years. However, the use of solar energy as a source of energy and power only has a history of more than 300 years. It is a recent thing to truly regard solar energy as "an urgently needed supplementary energy in the near future" and "the foundation of the future energy structure". Since the 1970s, solar energy technology has advanced by leaps and bounds, and the use of solar energy has been changing with each passing day. The history of modern solar energy utilization can be counted from the French engineer Solomon de Cox invented the first solar-powered engine in the world in 1615. This is a machine that uses solar energy to heat air to expand and perform work to pump water. Between 1615 and 1900, many solar power plants and some other solar power plants were developed in the world. (1) During the 100 years of the 20th century, the development history of solar energy technology can be roughly divided into seven stages.
1. During this stage from 1900 to 1920, the focus of solar energy research in the world was still solar power devices, but diversified concentrating methods were used and flat-plate collectors and low-boiling point working fluids began to be used. The devices were gradually expanded and the maximum output power reached 73.64kW. Typical installations built are: in 1901, a solar pumping device was built in California, USA, using a truncated cone concentrator, power: 7.36kW; from 1902 to 1908, five sets of dual-cycle solar engines were built in the US, using flat panels Collector and low boiling point working fluid; in 1913, a solar water pump composed of 5 parabolic trough mirrors was built south of Cairo, Egypt, with a total lighting area of 1,250m2.
2. 1920~1945 In the past 20 years, solar energy research work was at a low ebb, and the number of people participating in research work and research projects were greatly reduced. The reason was the large-scale development and utilization of fossil fuels and the occurrence of the Second World War.
3. 1945~1965 In the 20 years after the end of the Second World War, solar energy research work gradually resumed and carried out, and solar academic organizations were established, academic exchanges and exhibitions were held, and the solar energy research boom was once again rising. At this stage, solar energy research has made some significant progress. The more prominent ones are: in 1945, the practical silicon solar cell was developed, which laid the foundation for the large-scale application of photovoltaic power generation; in 1955, Israel Taber and others proposed selective coating at the first international solar thermal science conference. Basic theory, and developed into practical black nickel and other selective coatings, creating conditions for the development of high-efficiency collectors. In addition, there are other important achievements. For example, in 1952, the French National Research Center built a solar furnace with a power of 50kW in the eastern part of the Pyrenees. In 1960, the world's first ammonia-water absorption air-conditioning system heated by flat-plate collectors was built in Florida, USA. In 1961, a Stirling engine with a quartz window came out. In this stage, the research on the basic theories and basic materials of solar energy has been strengthened, and major breakthroughs have been made in technologies such as solar selective coatings and silicon solar cells. Flat-plate collectors have made great progress and mature in technology. Progress has been made in the research of solar absorption air conditioners, and a number of experimental solar houses have been built. Preliminary research on the difficult Stirling engine and tower solar thermal power generation technology.
4. During the period from 1965 to 1973, the research work of solar energy stagnated. The main reason was that solar energy utilization technology was in the growth stage, not yet mature, and the investment was large, the effect was not ideal, it was difficult to compete with conventional energy sources, and the public and enterprises were not available. And the government’s attention and support.
5. The outbreak of the oil crisis from 1973 to 1980 made people realize that the existing energy structure must be completely changed and the transition to the future energy structure should be accelerated. As a result, many countries, especially industrialized countries, have reinforced their support for the development of solar energy and other renewable energy technologies, and the development and utilization of solar energy has once again risen in the world. During this period, solar energy
The development and utilization work is in an unprecedented period of great development. Countries have strengthened the planning of solar energy research, and many countries have formulated short-term and long-term sunlight plans. The development and utilization of solar energy has become a government action, and support has been greatly strengthened. International cooperation is very active, and some third world countries have begun to actively participate in the development and utilization of solar energy. The field of research continues to expand, and the research work is getting deeper and deeper, and a number of major achievements have been made, such as vacuum heat collectors, amorphous silicon solar cells, and hydrogen production by photolysis of water. However, the solar energy development plans formulated by various countries generally suffer from excessive requirements and urgency, and the difficulties in the implementation process are underestimated.
6. From 1980 to 1992, the tide began to ebb after entering the 1980s, and gradually entered the trough. Many countries in the world have drastically reduced solar energy research funding one after another, of which the United States is the most prominent. The main reasons for this phenomenon are: the world oil prices have fallen sharply, while the prices of solar energy products remain high and lack competitiveness; there is no major breakthrough in solar energy technology, and the goals of improving efficiency and reducing costs have not been achieved. Affected by the decline of international solar energy in the 1980s, my country's solar energy research work has also been weakened to a certain extent. At this stage, although the solar energy development and research funding has been drastically reduced, the research work has not been interrupted, and some projects are still making great progress, and it has prompted people to carefully review the past plans and goals set, adjust the focus of research work, and strive for Smaller investment achieves greater results.
7. From 1992 to present, due to the massive burning of fossil energy, it caused global environmental pollution and ecological destruction, posing a threat to the survival and development of mankind. In this context, the United Nations convened the "World Conference on Environment and Development" in Brazil in 1992. The conference passed a series of important documents such as the Rio de Janeiro Declaration on Environment and Development and Agenda 21, bringing environment and development into a unified framework. Established a sustainable development model. After this meeting, countries around the world have strengthened the development of clean energy technologies, combining the use of solar energy with environmental protection, so that the use of solar energy has been stepped out of the trough and gradually strengthened. After the World Environmental Protection Conference, the Chinese government attached great importance to the environment and development, put forward 10 countermeasures and measures, and clearly defined the need to "develop and promote clean energy such as solar energy, wind energy, geothermal energy, and tidal energy according to local conditions", and formulated the "China Agenda 21 ", further clarified key solar energy development projects. After 1992, the use of solar energy in the world has entered a development period. The use of solar energy is closely integrated with the world’s sustainable development and environmental protection; solar energy development goals are clear, key points are prominent, and measures are effective; while increasing solar energy research and development efforts, pay attention to scientific and technological achievements Transform into productivity, develop the solar energy industry, accelerate the process of commercialization, expand the field and scale of solar energy utilization, and gradually increase economic benefits; international cooperation in the field of solar energy is unprecedentedly active.