The border of China starts from the south of Zengmu Ansha in the Xisha Islands near 4°N latitude to the north to the heart of Heilongjiang River north of Mohe, Heilongjiang Province at 53°31’N latitud; and starting from the Pamirs plateau near 73°40’ east longitude in the west, and reaching the confluence of the Heilongjiang and Ussuri rivers at 135°05’ east longitude in the east, the land is vast and vast.

China’s land area, from south to north, from west to east, is more than 5000km away, with a total area of 9.6×106km², which is 7% of the world’s total land area and ranks third in the world. In China’s vast and fertile land, there are very rich solar energy resources. The total annual solar radiation throughout the country is 3340~8400MJ/m², with a median value of 5852MJ/m². From the distribution of total solar radiation in China, Tibet, Qinghai, Xinjiang, Southern Ningxia, Gansu, Southern Inner Mongolia, Northwestern Shanxi, Northern Shaanxi, Liaoning, Southeastern Hebei, Southeastern Shandong, Southeastern Henan, Western Jilin, Central and Southwestern Yunnan, southeastern Guangdong, southeastern Fujian, east and west of Hainan Island, and southwestern Taiwan have a large total solar radiation. 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, the city of Lhasa, known as the “Sunshine City”, from 1961 to 1970, the average annual sunshine time is 3005.7h, the relative sunshine is 68%, the annual average sunny day is 108.8d, the cloudy sky is 98.8d, the annual average cloud cover is 4.8, and the annual total solar radiation is 8160MJ/ m², higher than other provinces and regions of the country and the same latitude. Sichuan and Guizhou provinces and Chongqing have the smallest total annual solar radiation, especially the Sichuan Basin, where there is more rain, fog, and less sunny days. For example, in Chongqing, 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, the cloudy days are 244.6 days, and the annual average cloud cover is as high as 8.4. The total annual solar radiation in other regions is in the middle.

The main characteristics of China’s solar resource distribution are:

(1) Both the high-value center and the low-value center of solar energy are located in the 22°~35° north latitude zone. The Qinghai-Tibet Plateau is the high-value center 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. Except for the Tibet and Xinjiang autonomous regions, the total amount of solar radiation 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 in the 30°~40° north latitude area 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.

In order to make better use of solar energy in accordance with different conditions in various parts of China, the country can be divided into five types of regions. The next article will introduce the five types of regions of China’s solar energy resources.