Direct Normal Radiation from Global Radiation for Indian Stations

Direct Normal Radiation has been computed from global radiation for three Indian stations New Delhi, Jodhpur and Bhavnagar, because it was seen that it has a strong relation with global radiation. Here relation in the form of linear, quadratic and cubic equation, have been tried. A quadratic relation between direct normal radiation and global radiation gives best results. The differences in measured daily values of direct normal radiation and computed by the so developed quadratic relation is about ± 0.6% on daily basis. Difference on hourly basis, is within ± 11%.