Performance Evaluation of Isotropic and Anisotropic Empirical Models for Estimation of Solar Irradiance Over Inclined Surfaces at Different Geographical Locations

The aim of this effort is to evaluate the performance of various empirical relationships available for computation of solar radiation over tilted surface. In this work we have considered four isotropic models and four anisotropic models for evaluation of radiation over titled surface. The angle of inclination was fixed equivalent to the geographical latitude of the area under study. Two different locations have been considered for computation purpose, New Delhi, the national capital of India, situated in the sub-tropical belt of globe and Bhopal, a city located in the central part of India, near the Tropic of Cancer. All the computations have been carried out in the MATLAB environment. It has been deduced that Badescu model has exhibited the lowest amount of error and has predicted the value of radiation nearest to the measured data. This is an isotropic model. While Klucher’s model has shown the highest error for the considered geographic locations. Thus, Badescu’s empirical relationship can be realized for calculation of solar irradiance over inclined planes in this geographical belt and can hence provide support for solar PV applications.