Page 102 - Design of Solar Thermal Power Plants

90 2. THE SOLAR RESOURCE AND METEOROLOGICAL PARAMETERS

calculated solar radiation resources by utilizing satellite cloud images and
estimated the solar direct normal radiation resources in North Africa.
ZUO Dakang et al. carried out studies on the spatial distribution char-
acteristics of global solar radiation in domestic areas for the first time and
drew monthly and yearly global radiation distribution charts for China.
Using radiation measurement through satellite remote sensing, FU
Bingshan et al. established a statistical model of satellite-measured values
as well as solar direct and scattered radiation that corresponded to
various heights in the atmosphere under clear weather conditions by
utilizing data from radiosonde stations located in southeast coastal areas
of China. Satellite remote sensing data are connected in terms of spatial
distribution yet separated in terms of time distribution; furthermore, data
quality is easily influenced by weather conditions. There exist certain
difficulties in inverting the status of ground solar radiation based on
current techniques. China’s solar resource division indices were first
proposed by a domestic scholar named Wang Bingzhong in 1983, and
since then many researchers have studied the spatial and time distribu-
tions and division of solar resources in partial provinces and cities on the
basis of observational data from meteorological stations. A common
conclusion of solar radiation research has been proposed; that is, solar and
direct radiation in partial domestic areas have shown decreased tendency,
which likely is caused by an increased concentration of suspended par-
ticles in the atmosphere. Recent research has indicated that from the 1960s
to 1980s, China’s direct radiation resources as a whole have shown
decreased tendency; yet since the 1990s, decreased tendency has stopped,
and there has even been some increased tendency.

2.7.1 Distribution of China’s Annual Mean Daily Solar Direct
Normal Irradiation

China has abundant solar resources. According to rough calculations
and estimations, the mean global annual irradiation on horizontal surfaces
2
for the entire country over the past 30 years is 5648 MJ/m ; in areas ac-
counting for more than two-thirds of the total area, annual global solar
2
irradiation has exceeded 5000 MJ/m . China enjoys favorable conditions
for solar energy utilization. General characteristics of China’s global
annual radiation distribution show a trend of the west being higher than
the east.
In the west, annual global solar radiation shows a zonal distribution
with the south being higher than the north, in which southern Tibet (except
for the Shannan Prefecture) and the Qaidam Basin have higher solar
radiation; the Tarim and Turpan Basins in Xinjiang have lower amounts.