In order to make better use of solar energy in accordance with the different conditions of each region, Chinese researchers in the 1980s divided the country into the following five types of regions according to the total amount of solar radiation received by each region.

1. First-class area

The annual sunshine hours are 3200~3300h. The total amount of solar radiation received in one year per square meter area is 6680~8400MJ, which is equivalent to the heat emitted by burning 225~285kg of standard coal. It mainly includes northern Ningxia, northern Gansu, southeastern Xinjiang, western Qinghai, and western Tibet. It is the region with the richest solar energy resources in China, which is equivalent to the solar energy resources of India and northern Pakistan. In particular, the western part of Tibet has the most abundant solar energy resources, with annual sunshine hours reaching 2900~3400h and annual total radiation as high as 7000~8000MJ/m², second only to the Sahara Desert, ranking second in the world.

2. Second-class area

The annual sunshine hours are 3000~3200h. The total amount of solar radiation received in one year per square meter area is 5852-6680J, which is equivalent to the heat emitted by the burning of 200-225kg standard coal. It mainly includes northwestern Hebei, northwestern Shanxi, southern Inner Mongolia, southern Ningxia, central Gansu, eastern Qinghai, southeastern Tibet, and southern Xinjiang. It is an area with abundant solar energy resources in China, which is equivalent to Jakarta, Indonesia.

3. Three-class of area

The annual sunshine hours are 2200~3000h. The total amount of solar radiation received in a year per square meter area is 5016~5852MJ, which is equivalent to the heat emitted by the combustion of 170~200kg of standard coal. It mainly includes Southeastern Shandong, Southeastern Henan, Southeastern Hebei, southwestern Shanxi, northern Xinjiang, Jilin, Liaoning, Yunnan, northern Shaanxi, southeastern Gansu, southern Guangdong, southern Fujian, northern Jiangsu, northern Anhui, Tianjin, Beijing, and southwestern Taiwan. It is a medium-sized area of solar energy resources in China, which is equivalent to the Washington area of the United States.

4. Four-class of area

The annual sunshine hours are 1400-2200h. The total amount of solar radiation received in one year per square meter area is 4190-5016MJ, which is equivalent to the heat emitted by the combustion of 140-170kg standard coal. It mainly includes Hunan, Hubei, Guangxi, Jiangxi, Zhejiang, northern Fujian, northern Guangdong, southern Shaanxi, southern Jiangsu, southern Anhui, Heilongjiang, and northeastern Taiwan. It is an area with poor solar energy resources in China, which is equivalent to the Milan area of Italy.

5. Five-class of area

The annual sunshine hours are 1000~1400h. The total amount of solar radiation received in one year per square meter area is 3344-4190MJ, which is equivalent to the heat emitted by the combustion of 115-140kg standard coal. It mainly includes Sichuan, Guizhou, Chongqing and other places. It is the region with the least solar energy resources in China, which is equivalent to most areas in Europe.

Areas of Type 1, 2, and 3, with annual sunshine hours greater than 2200h, and the total annual solar radiation is more than 5016MJ/m², which is a region with rich or abundant solar energy resources in China. It has a large area, accounting for more than 2/3 of the total area of the country, and has good conditions for solar energy utilization. Although the solar energy resources are in poor conditions in the fourth and fifth types of regions, they also have certain utilization value, and some of them may be developed and utilized. In short, from a national perspective, China is a country rich in solar energy resources, and has unique advantages for developing solar energy utilization. Compared with other countries at the same latitude, China’s solar energy resources are abundant in most regions except the Sichuan Basin and adjacent areas, similar to the United States, and much better than Japan and Europe, especially the western and southeastern parts of the Qinghai-Tibet Plateau, which are close to the world’s most famous Sahara Desert.

The distribution of solar energy resources has obvious regional characteristics. This distribution characteristic reflects that solar energy resources are restricted by climate and geographical conditions. According to the annual solar radiation exposure, China can be divided into four solar resource belts, as shown in Figure 1.