Kipp&Zonen CM 121 B/C Shadow Ring - Manual (Page 22)

5. MEASUREMENT OF THE DIFFUSE SKY RADIATION
Instruction manual CM 121 21
5.3 Diffuse sky radiation on a tilted plane
The correction factors are only valid for a pyranometer in the horizontal position.
However, for a pyranometer tilted T degrees to the south and on latitude B, the configuration of ring
and pyranometer is the same as for a horizontal pyranometer at latitude (B - T) degrees.
You can derive a list of correction factors for a tilted pyranometer from table 1 in 5.2, taking into
account that only part of the hemisphere is 'seen' by the pyranometer. However, this correction
does not take the effect of ground-reflected radiation into account. The correction for this is very
much dependant on local conditions and might vary throughout the day as a function of the solar
position, and throughout the year as a function of ground properties. Therefore this is the responsi-
bility of the customer.