Do you understand the five stages of development of solar energy?

The first stage (1900~1920):

At this stage, the focus of solar research in the world is still solar power plants, but the concentrating method is diversified, and the use of flat plate collectors and low-boiling working fluids has begun, and the device has been gradually expanded, with a maximum output of 73.64 kW. The practical purpose is clear and the cost is still high. The typical installations were: 1901, a solar pumping unit was built in California, using a frustoconical concentrator, power: 7.36 kW; from 1902 to 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 consisting of 5 parabolic trough mirrors was built in the south of Cairo, Egypt, each with a length of 62.5m, a width of 4m and a total lighting area of ​​1,250m2.

The second stage (1920~1945):

In the past 20 years, solar research work has been at a low ebb, and the number of people participating in research work and research projects have been greatly reduced. The reasons are related to the massive development and utilization of fossil fuels and the occurrence of the Second World War (1935~1945), and solar energy. It was not able to solve the urgent need for energy at that time, so the research work on solar energy was gradually ignored.

The third stage (1945~1965):

In the 20 years after the end of the Second World War, some far-sighted people have noticed that oil and natural gas resources are rapidly decreasing, calling for people to pay attention to this issue, which gradually promoted the recovery and development of solar research work, and established Solar energy academic organizations, holding academic exchanges and exhibitions, once again raised the solar research boom. At this stage, solar energy research has made some significant progress. The more prominent ones are: In 1945, Bell Labs of the United States developed a practical silicon solar cell, which laid the foundation for large-scale application of photovoltaic power generation; in 1955, Israel Taber, etc. At the first international solar thermal science conference, the basic theory of selective coating was proposed, and a practical selective coating such as black nickel was developed, which created conditions for the development of high-efficiency collectors. In addition, there are other important achievements in this stage, notably: In 1952, the French National Research Center built a 50kW solar furnace in the eastern Pyrenees. In 1960, the world's first ammonia-water absorption air conditioning system with flat-plate collectors was built in Florida, with a cooling capacity of 5 tons. In 1961, a Stirling engine with a quartz window was introduced. In this phase, the research on basic solar energy theory and basic materials has been strengthened, and major technological breakthroughs such as solar selective coating and silicon solar cells have been achieved. The flat panel collector has been greatly developed and matured in technology. Research on solar absorption air conditioners has progressed and a number of experimental solar houses have been built. A preliminary study of the more difficult Stirling engine and tower solar thermal power generation technology was carried out.

The fourth stage (1965~1973):

At this stage, the research work on solar energy has stagnated. The main reason is that solar energy utilization technology is in the stage of growth, it is still immature, and the investment is large, the effect is not ideal, and it is difficult to compete with conventional energy, so it is not available to the public, enterprises and government. Value and support.

The fifth stage (1973~1980):

Since the role of oil in the world's energy structure, oil has become a key factor in the economy and in determining the survival, development and decline of a country. In 1973, the Middle East war broke out, and the Organization of Petroleum Exporting Countries adopted measures such as reducing oil production and raising prices. Support the struggle of the people of the Middle East and safeguard the interests of the country. As a result, countries that rely on large imports of cheap oil from the Middle East have been hit hard by the economy. As a result, some people in the West exclaimed: The world has experienced an "energy crisis" (some called the "oil crisis"). This "crisis" objectively makes 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 re-enforced their support for the development of solar energy and other renewable energy technologies, and the development and utilization of solar energy has once again emerged in the world. In 1973, the United States established a government-level solar power generation plan, a substantial increase in solar research funding, and the establishment of a solar development bank to promote the commercialization of solar energy products. In 1974, Japan announced the government's “Sunshine Plan”, 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. In order to implement this plan, the Japanese government has invested a lot of manpower, material resources and financial resources. The development and utilization of solar energy in the world in the early 1970s has also had a huge impact on China. Some forward-thinking scientific and technical personnel have devoted themselves to the solar energy industry, actively making recommendations to relevant government departments, publishing books and publishing, introducing the international use of solar energy; promoting the use of solar cookers in rural areas, developing solar water heaters in cities, and using solar energy for space. The battery starts to be applied on the ground... In 1975, the “National First Solar Energy Utilization Work Experience Exchange Conference” was held in Anyang, Henan Province, which further promoted the development of China's solar energy industry. After this meeting, solar energy research and promotion work was incorporated into the government plan of our country, and it received special funds and material support. Some universities and research institutes have set up solar energy research groups and research institutes, and some places have begun to build solar energy research institutes. At that time, China also developed a boom in the development and utilization of solar energy. During this period, solar energy development and utilization work was in an unprecedented period of development, with the following characteristics:

The solar energy development plans formulated by various countries generally have excessive and urgent requirements, and the estimation of difficulties in the implementation process is insufficient. It is hoped to replace fossil energy in a short period of time and realize large-scale utilization of solar energy. For example, the United States had 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 later adjusted, and the space solar power plant has not yet been launched.