Page 111 - Design of Solar Thermal Power Plants

2.7 DISTRIBUTION OF SOLAR DIRECT NORMAL RADIATION 99

TABLE 2.17 Main Configuration of a Solar Irradiance Testing Station
Name Quantity
Data collecting instrument 1
Base with batteries 1
Pyrheliometer ISO primary standard 1
Solar position tracker 1
Case Heating plate 1
Pyranometer ISO secondary standard 1
Scattered radiation meter, ISO secondary standard 1
Artificial ventilating hood 1
Atmospheric long wavelength radiation meter 1
Reflection radiation meter 1
Pallet-mounted with a reflection radiation meter 1
Ground long wavelength radiation meter 1
Pallet-mounted with a ground long wavelength radiation meter 1
Communication unit 1

FIGURE 2.13 Measured values of direct normal irradiance for month of December, 2011
in Badaling (statistical period: 10 min).

and diffuse irradiance is insignificant, yet on a cloudy day as shown in
Fig. 2.15, the global irradiance on the horizontal surface is more than the
DNI and diffuse irradiance on the horizontal surface is equivalent to
global irradiance.