New correction factor for the estimation of solar radiation

A new correction factor (CF_year) depending upon the longitude and altitude of a location has been introduced in place of the clearness index (K_t year) used for the estimation of solar irradiation H. Thirty different geographical locations have been taken for comparing the values of K_t year and CF_year. The results show that the values of K_t year and CF_year are in close agreement, having variation within 10%. The estimated values of H for K_t year and CF_year have also been compared using 15 year measured data of 11 Indian cities to establish the accuracy of the CF over K_t. The annual mean percentage error between the estimated and measured values of these locations has been found to be within 10%. The monthwise variation in the estimated values of the 11 Indian cities compared with their measured values also proved the better accuracy of CF than K_t. The study reveals that solar radiation can be estimated using CF without applying any meteorological parameters for the locations having a longitude range of ±70 to ±125.