China’s solar energy resources

The boundary of China starts from the south of Zengmu Shoal in the Nansha Islands near latitude 4°N in the south to the center of Heilongjiang River in the north of Mohe, Heilongjiang Province in the north at 53°31’N, starts from the Pamir Plateau near the east longitude 73°40′ in the west and reaches the confluence of the Heilongjiang and Ussuri rivers in the east at 135°05′ east longitude. The land is vast and the territory is vast. China’s land area is about 5,500km long from south to north and 5,200km from east to west, with a total area of 9.6 million square kilometers, accounting for 7% of the world’s total land area, ranking third in the world. In China’s vast and rich land, there are very rich solar energy resources. The total annual solar radiation across the country is 3340-8 400MJ/m2, with a median value of 5852MJ/m2. From the distribution of total annual solar radiation in China, the total solar radiation in Tibet, Qinghai, Xinjiang, northern Ningxia, Gansu, southern Inner Mongolia, northern Shanxi, northern Shaanxi, Liaoning, southeastern Hebei, southeastern Shandong, southeastern Henan, western Jilin, central and southwestern Yunnan, southeastern Guangdong, southeastern Fujian, eastern and western Hainan Island, and southwestern Taiwan Province is very large. In particular, 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, in Lhasa, which is called “Sunlight City”, the average annual sunshine time from 1961 to 1970 is 3005.7h, the relative sunshine is 68%, and the annual average sunny day is 108.5d, the cloudy sky is 98.8d, the annual average cloud amount is 4.8, and the annual total solar radiation is 8160MJ/m2, which is higher than other provinces and regions in the country and the same latitude. The Sichuan Basin (including Chongqing City) and Guizhou Province have the smallest total annual solar radiation, especially the Sichuan Basin, where there is more rain, more fog, and less sunny days. For example, in Chongqing, known as the “Fog City”, the annual average sunshine time is only 1152.2h, the relative sunshine is 26%, and the annual average sunny day is 24.7d, the cloudy sky is 244.6 days, the annual average cloud amount is as high as 8.4, and the total annual solar radiation in other areas is in the middle.

The main characteristics of the distribution of solar energy resources in China are:

① The high-value center and low-value center of solar energy are both located in the area of 22°~35° north latitude, the Qinghai-Tibet Plateau is the high-value center, and the Sichuan Basin is the low-value center;

②The total annual solar radiation is higher in the western region than in the eastern region, and except for the two autonomous regions of Tibet and Xinjiang, the southern region is basically lower than the northern region;

③Due to the cloudy and rainy weather in most areas in the south, in the 30°~40° north latitude area, the distribution of solar energy is opposite to the general law of solar energy changing with latitude, the solar energy does not decrease with increasing latitude, but increases with increasing latitude.

In order to make better use of solar energy according to different conditions in different places, in the 1980s, Chinese researchers divided the country into five types of regions according to the total amount of solar radiation received by each region. The next article will introduce the five regions of China’s solar energy resources in detail.

Compared with other countries at the same latitude, China’s solar energy resources are quite rich in solar energy resources in most regions, except for eastern Sichuan, most of Chongqing, central and northern Guizhou and its adjacent areas, similar to those of the United States and far superior to Japan and Europe. In particular, the western and southeastern parts of the Qinghai-Tibet Plateau are particularly rich in solar energy resources, 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 climatic and geographical conditions. From 1971 to 2000, the annual total solar radiation received by China’s land surface was equivalent to 1.7 trillion tons of standard coal. The total solar radiation resources are generally larger in the west than in the east, the plateau is larger than the plain, the inland is larger than the coast, and the dry area is larger than the humid area, the spatial distribution characteristics of the annual total direct radiation are basically consistent with the total radiation. Southwest Tibet, central Qinghai, western Inner Mongolia, and southern Xinjiang are the areas with the most abundant direct radiation resources. According to the annual solar radiation exposure, China can be divided into four solar resource belts.