Mankind has used solar energy for more than 3,000 years, and the use of solar energy as an energy source and power has only a history of more than 300 years. It is a matter of recent years that solar energy is truly regarded 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 utilization of solar energy has changed with each passing day. During the 100 years of the 20th century, the history of solar energy technology development can be roughly divided into 7 stages. The first five stages are introduced as follows.

The first stage (1900-1920). At this stage, the focus of solar energy research in the world is still solar power devices. However, the concentrating methods used are diversified, and flat-plate collectors and low-boiling point working fluids are beginning to be used. The device is gradually expanded, and the maximum output power reaches 73.64 kW. The practical purpose is relatively clear and the cost is high.

The second stage (1920-1945). In the past 20 years, solar energy research has been at a low ebb, and the number of people participating in research work and research projects has been greatly reduced. The reason was related to the massive development and utilization of fossil fuels and the Second World War (1935-1945). Solar energy could not solve the urgent need for energy at that time, so solar energy research was gradually neglected.

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. They called on people to pay attention to this issue, which gradually promoted the recovery and development of solar energy research, and established solar academic organizations, held academic exchanges and exhibitions, and once again raised the upsurge of solar energy research. At this stage, solar energy research has made some significant progress.

The fourth stage (1965-1973). At this stage, research on solar energy has stagnated. The main reason is that the solar energy utilization technology is in the growth stage, not yet mature, and the investment is large, the effect is not ideal, and it is difficult to compete with conventional energy, so it does not get the attention and support of the public, enterprises and the government.

The fifth stage (1973-1980). Since oil has played the leading role in the world’s energy structure, oil has become a key factor influencing 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. So many countries, especially industrialized countries, have reinforced their support for the development of solar energy and other renewable energy technologies, and the upsurge in the development and utilization of solar energy has once again risen in the world. In the early 1970s, the upsurge in the development and utilization of solar energy in the world also had a huge impact on our country. 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; Promote the application of solar cookers in rural areas, develop solar water heaters in cities, and begin to use solar cells for space on the ground. 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.