Page 78 - Design of Solar Thermal Power Plants

68 2. THE SOLAR RESOURCE AND METEOROLOGICAL PARAMETERS

FIGURE 2.8 Typical weather of the four seasons in Badaling, Beijing.

TABLE 2.5 Typical Daily Mean Direct Normal Irradiance and Sunshine Duration of
the Seasons
Effective
Daily Mean Effective
Daily DNI Sunshine
2
Mean (>300 W/m )/ Duration Sunshine
2
2
Time DNI (W/m ) (>300 W/m )/h Duration/h
Spring (March 25) 651 713 11 12
Summer (June 29) 656 710 13 14
Autumn (September 21) 571 662 8.5 12
Winter (December 21) 47 547 7 8

DNI, direct normal irradiance.

four seasons in Badaling, Beijing, which are summarized in Table 2.5.
Sunrise and sunset times are shown in Fig. 2.8 as well. When DNI is more
2
than 300 W/m , the solar resource is of a certain significance for thermal
power generation. Therefore, in Table 2.5, “effective daily mean DNI,”
“effective sunshine duration,” and “sunshine duration” have been
specifically summarized.
As indicated in Table 2.5, sunshine duration varies greatly by season. In
summer, the sun rises at 5:00 a.m. and does not set until 7:30 p.m., whereas
during winter, the sun rises just after 8:00 a.m. and sets around 4:30 p.m.