Page 270 - Applied Photovoltaics

Appendix

C

CHARACTERISTIC

DAYS AND

DECLINATIONS

In solar energy availability estimations, it is common to use characteristic days and
declination values to represent each month. For the monthly characteristic
declinations, the extraterrestrial insolation is equal to its monthly average value. The
values given in Table C.1 are reproduced from Table 4.2.1 of Iqbal (1983).

Table C.1. Character days and declinations.
month date declination characteristic day number
(°)
January 17 –20.84 17
February 14 –13.32 45
March 15 –2.40 74
April 15 +9.46 105
May 15 +18.78 135
June 10 +23.04 161
July 18 +21.11 199
August 18 +13.28 230
September 18 +1.97 261
October 19 –9.84 292
November 18 –19.02 322
December 13 –23.12 347

REFE RE NCES

Iqbal, M. (1983), An Introduction to Solar Radiation, Academic, Toronto.