From the distribution of total solar radiation in China, Tibet, Qinghai, Xinjiang, southern Inner Mongolia, Shanxi, northern Shaanxi, Hebei, Shandong, Liaoning, western Jilin, central and southwestern Yunnan, southeast Guangdong, southeast Fujian, and Hainan The total amount of solar radiation in vast areas such as the eastern and western parts of the island and the southwestern part of Taiwan Province of China is very large. Especially the Qinghai-Tibet Plateau is the largest, where the average altitude is above 4000m, the atmosphere is thin and clean, the transparency is good, the latitude is low, and the sunshine time is long. For example, Lhasa, known as the “Sunlight City”, had an annual average sunshine time of 3005.7h from 1961 to 1970, a relative sunshine of 68%, an annual average of 108.5 days of sunny days, 98.8 days of cloudy days, and a total solar radiation of 816KJ. /(Cm²·a), which is higher than other provinces and regions of China and regions of the same latitude. China’s Sichuan and Guizhou provinces have the smallest total annual solar radiation, especially the Sichuan Basin, where there is a lot of rain, fog, and less sunny days. For example, in Chengdu, known as the “Fog City”, the annual average sunshine hours is only 1152.2h, the relative sunshine is 26%, the annual average sunny days are 24.7 days, and the cloudy days are 244.6 days. The total annual solar radiation in other regions Centered.
1. The main characteristics of China’s solar resource distribution
(1) The high-value center of solar energy is the Qinghai-Tibet Plateau, and the Sichuan Basin is the low-value center.
(2) The total annual solar radiation is higher in the western region than in the eastern region, and with the exception of Tibet and Xinjiang, it is basically lower in the south than in the north.
(3) Since most areas in the south are cloudy and rainy, the distribution of solar energy is contrary to the general law of solar energy changing with latitude. Solar energy does not decrease with the increase of latitude, but increases with the increase of latitude.
2. Regional division of China’s solar energy resources
In order to make better use of solar energy, Chinese researchers in the 1980s divided China 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 in the first-class area is 3200~3300h, and the radiation amount is 670x 104~837x 104KJ/(cm²·a). It is equivalent to the heat emitted by burning 225~285kg standard coal. It mainly includes northern Ningxia, northern Gansu, southeastern Xinjiang, western Qinghai, and western Tibet. These regions are the regions with the most abundant solar energy resources in China, which are comparable to those in India and northern Pakistan. In particular, the western part of Tibet has the most abundant solar energy resources. The annual sunshine hours are 2900~3400h, and the total annual radiation is as high as 7000~8000MJ/m². It is second only to the Sahara Desert and ranks second in the world. Lhasa is the most famous in the world. Sunshine City.
2) Second-class area
The annual sunshine hours in the second-class area is 3000~3200h, and the radiation amount is 586×104~670×104kJ/(cm²·a), which is equivalent to the heat emitted by the combustion 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. These areas are relatively rich in solar energy resources in China, equivalent to the area around Jakarta in Indonesia.
3) Three types of areas
The annual sunshine hours in the third category area is 2200~3000h, and the radiation amount is 502×104~586×104kJ/(cm²·a), which is equivalent to the heat emitted by the combustion of 170~200kg standard coal. Mainly include Shandong, Henan, southeastern Hebei, southwestern Shanxi, northern Xinjiang, Jilin, Liaoning, Yunnan, northern Shaanxi, southeastern Gansu, southern Guangdong, southern Fujian, northern Jiangsu and northern Anhui, Tianjin, Beijing and southwestern Taiwan, etc. land. These areas are the medium-type areas of China’s solar energy resources, which are equivalent to the Washington area of the United States.
4) Four types of areas
The annual sunshine hours of the four types of areas are 1400-2200h, and the radiation amount is 419×104~502×104kJ/(cm²·a), 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. These areas are areas with poor solar energy resources in China, equivalent to the Milan area in Italy.
5) Five types of areas
The annual sunshine hours of the five types of areas are 1000~1400h, and the radiation amount is 335×104~419×104kJ/(cm²·a), which is equivalent to the heat emitted by the combustion of 115~140kg standard coal. It mainly includes two provinces, Sichuan and Guizhou. These regions are the regions with the least solar energy resources in China, equivalent to most regions in Europe.
The annual sunshine hours of the first, second and third types of areas are more than 2000h, and the total radiation is more than 586KJ/(cm²·a). It is a region with rich or abundant solar energy resources in China, with a large area, accounting for about 2 of the total area of China. /3 or more, with good conditions for using solar energy. Although the solar energy resource conditions are relatively poor in the fourth and fifth types of regions, they still have certain utilization value.
Compared with other countries at the same latitude, China’s solar energy resources are quite abundant in most regions except the Sichuan Basin and its adjacent areas, similar to the United States, and much better than Japan and Europe, especially the Qinghai-Tibet Plateau. Solar energy resources are particularly rich in the west and southeast of the country, close to the most famous Sahara Desert in the world.
Research in recent years has found that with the increase of air pollution, the amount of solar radiation in various places has shown a downward trend.
3. Solar light time comparison table
When calculating the working time of solar cells, the sunshine time should not be regarded as the time when there is sunlight every day. If the calculation time is selected to be about 8h, it will cause unstable factors to the entire photovoltaic power generation system. In the design, the effective working time of solar cells should be distinguished according to the lighting conditions in different regions, and the calculation should be performed according to the comparison table of solar light time .
| Area Classification | Annual light radiation (kW/m²) | Average peak time (h) |
| Rich area | ≥586 | 5.10~5.42 |
| More abundant areas | 502~586 | 4.46~4.78 |
| Available area | 419~502 | 3.82~4.14 |
| Poor areas | ＜419 | 3.19~3.50 |
Only based on these parameters can we accurately calculate the lighting time in each region and accurately calculate the number and reliability coefficients of solar cell components used in the photovoltaic power generation part.