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According to records, mankind has used solar energy for more than 3000 years. The use of solar energy as a source of energy and power has only a history of more than 300 years. It is a recent thing to truly regard solar energy as an urgently needed supplementary energy 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. The invention 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. Almost all of these power devices use concentrating methods to collect sunlight. The engine power is not large, and the working fluid is mainly water vapor, which is expensive and has little practical value. Most of them are researched and manufactured by solar enthusiasts. During the 100 years of the 20th century, the history of solar technology development can be roughly divided into seven stages.
1. The first stage (1900-1920)
At this stage, the focus of solar energy research in the world is still solar power devices, but the use of diversified concentrating methods, and the use of flat-plate collectors and low-boiling point working fluids, the devices are gradually expanded, with a maximum output of 73.64kW. The practical purpose is relatively clear, and the cost is still high. Typical installations built are: In 1901, a solar pumping device was built in California, USA, using a truncated cone condenser with a power of 7.36kW; in 1902-1908, five sets of dual-cycle solar engines were built in the United States, using flat plates 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, each with a length of 62.5m and a width of 4m, with a total lighting area of 1250m².
2. The second stage (1920-1945)
In the past 20 years, solar energy research work has been at a low ebb, and the number of people participating in research work and research projects has been greatly reduced. The reason is related to the large-scale development and utilization of fossil fuels and the Second World War (1935~1945). It could not solve the urgent need for energy at that time, so solar energy research work was gradually neglected.
3. The third stage (1945-1965)
In the 20 years since the end of the Second World War, some visionaries have noticed that oil and natural gas resources are rapidly declining, and called on people to pay attention to this issue, which has gradually promoted the restoration and development of solar energy research, and established The solar academic organization, held academic exchanges and exhibitions, once again raised the upsurge of solar energy research. At this stage, some significant progress has been made in solar energy research. The most prominent ones are: In 1945, Bell Laboratories in the United States developed practical silicon solar cells, which laid the foundation for large-scale photovoltaic power generation applications; in 1955, Israel Taber, etc. At the first international solar thermal science conference, the basic theory of selective coating was proposed, and practical selective coatings such as black nickel were developed, which created conditions for the development of high-efficiency collectors. In addition, there are some other important achievements in this stage. The most prominent ones are: 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 was built in Florida, the United States. The first ammonia-water absorption air-conditioning system using flat plate collectors for heating, with a cooling capacity of 5 tons; in 1961, a Stirling engine with quartz windows came out. In this stage, the research on the basic theories and basic materials of solar energy has been strengthened, and major technological breakthroughs have been made, such as solar selective coatings and silicon solar cells. Flat-plate collectors have made great progress and gradually 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. The fourth stage (1965-1973)
At this stage, the research work of solar energy has stagnated, mainly because solar energy utilization technology is in the growth stage, is not yet mature, and the investment is large, the effect is not ideal, it is difficult to compete with conventional energy, and therefore the public, enterprises and government are not allowed. Value and support.
5. The fifth stage (1973~1980)
Since oil has played the leading role in the world's energy structure, oil has become a key factor in controlling the economy and determining the survival, development and decline of a country. The Middle East war broke out in October 1973. The Organization of Petroleum Exporting Countries adopted measures such as reducing oil production and raising prices to support the struggle of the people in the Middle East and safeguard their own interests. As a result, countries that rely on large quantities of cheap oil imported from the Middle East have suffered a severe economic blow. As a result, some people in the West exclaimed: The world has experienced an energy crisis (some call it an oil crisis).
This crisis objectively 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 industrially developed 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. In 1973, the United States formulated a government-level solar power generation plan, solar energy research funding increased substantially, and established a solar development bank to promote the commercialization of solar products. Japan announced the Sunshine Plan formulated by the government in 1974, in which solar energy research and development projects include: solar houses, industrial solar systems, solar thermal power generation, solar cell production systems, decentralized and large-scale photovoltaic power generation systems, etc. In order to implement this plan, the Japanese government has invested a lot of manpower, material resources and financial resources.
The upsurge in the development and utilization of solar energy that appeared in the world in the early 1970s also had a huge impact on China. Some far-sighted scientific and technological personnel have devoted themselves to the solar energy industry, actively making suggestions to the relevant government departments, publishing books and publications, introducing the development of solar energy utilization in the world; promoting the application of solar cookers in rural areas, developing solar water heaters in cities, and solar energy for space. Batteries began to be applied on the ground... In 1975, the First National Solar Energy Utilization Experience Exchange Conference held in Anyang, Henan Province further promoted the development of China's solar energy industry. After this meeting, solar energy research and promotion work was incorporated into the Chinese government's plan, and special funds and material support were obtained. Some universities and scientific research institutes have set up solar energy research groups and research laboratories one after another, and some places have begun preparations for the establishment of solar energy research institutes. At that time, there was also an upsurge in the development and utilization of solar energy in China.
During this period, the development and utilization of solar energy was in an unprecedented period of great development. It has the following characteristics: various countries have strengthened the planning of solar energy research work, 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 research field continues to expand, the research work is getting deeper and deeper, and a number of major achievements have been made, such as CPC, vacuum heat collectors, amorphous silicon solar cells, photolysis of water to produce hydrogen, and solar power generation.
The solar energy development plans formulated by various countries generally have the problems of excessive requirements and urgency, and underestimation of the difficulties in the implementation process. They hope to replace fossil energy in a relatively short period of time and realize large-scale use of solar energy. For example, the United States planned to build a small solar demonstration satellite power station in 1985 and a 5 million kW space solar power station in 1995. In fact, this plan was adjusted later, and the space solar power station has not yet been launched.
At this stage, solar water heaters, solar cells and other products began to be commercialized, and the solar energy industry was initially established, but the scale was small and the economic benefits were not yet satisfactory.
6. The sixth stage (1980-1992)
The upsurge in the development and utilization of solar energy that rose in the 1970s began to ebb shortly after entering the 1980s and gradually entered a 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 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, which has shaken some people's development. Confidence in the use of solar energy; the rapid development of nuclear power has inhibited the development of solar energy to a certain extent.
Affected by the decline of the international solar energy in the 1980s, China’s solar energy research work has also been weakened to a certain extent. Some people even pointed out that: solar energy utilization has large investment, poor effect, difficult energy storage, and large area. They believe that solar energy is the future energy and advocate foreign research. After success, China introduced technology. Although there are few people holding this view, it is very harmful and has a negative impact on the development of China's solar energy industry. 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 Larger results can be achieved with less investment.
7. The seventh stage (1992~present)
Due to the massive burning of fossil energy, it has caused global environmental pollution and ecological destruction, posing a threat to the survival and development of mankind. In this context, the United Nations held the World Conference on Environment and Development in Brazil in 1992. The conference adopted a series of important documents such as the Rio de Janeiro Declaration on Environment and Development, the 21st Century Conference and the United Nations Convention on Climate Change. A unified framework with development and inclusion has 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 Conference on Environment and Development, 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, tidal energy, and biomass energy in accordance with local conditions. China's 21st Century Agenda further clarifies the key development projects of solar energy.
In 1995, the State Planning Commission, the State Science and Technology Commission, and the State Economic and Trade Commission formulated the New Energy and Renewable Energy Development Outline, which clearly put forward China’s development goals, tasks, and corresponding countermeasures and measures for the development of new energy and renewable energy from 1996 to 2010. measure. The formulation and implementation of these documents have played an important role in further promoting China's solar industry. In 1996, the United Nations held the World Solar Energy Summit in Zimbabwe. After the meeting, the Harare Solar Energy and Sustainable Development Declaration was issued. At the meeting, the World Solar Energy 10-year Action Plan (1996-2005), Important documents such as the Solar Energy Convention and the World Strategic Plan for Solar Energy. This meeting further demonstrated the firm determination of the United Nations and other countries in the world to develop solar energy, requiring global joint action to make extensive use of solar energy.
After 1992, the world's solar energy utilization has entered a development period. Its characteristics are: solar energy utilization is closely integrated with the world's sustainable development and environmental protection, and the world is acting together to achieve the world's solar energy development strategy; solar energy development goals are clear and focused. Effective measures are conducive to overcoming the past shortcomings of cold and hot, overheating, and ensuring the long-term development of the solar industry; while increasing solar energy research and development, pay attention to the conversion of scientific and technological achievements into productivity, develop the solar energy industry, and accelerate commercialization Progress, expanding the field and scale of solar energy utilization, and gradually improving economic benefits; international cooperation in the field of solar energy has been unprecedentedly active, scaled up, and the effect is obvious. From the above review, it can be seen that during the 100 years of this century, the development of solar energy has not been smooth. Generally, there will be a low tide period after each high tide period, and the low tide period is about 45 years. The development process of solar energy utilization is completely different from that of coal, petroleum, and nuclear energy. People's understanding of it is very different, repeated, and the development time is long. On the one hand, it shows that solar energy development is difficult and it is difficult to realize large-scale utilization in a short time. On the other hand, it also shows that the use of solar energy is also affected by factors such as fossil energy, politics and wars, and the development path is relatively tortuous. Nevertheless, from an overall point of view, the technological progress of solar energy in the 20th century is still faster than in any previous century.