Evaluation and calibration of sunshine based solar radiation models for Tabriz, Iran

Abstract

Estimation of global solar radiation (Rs) value is essential for many applications such as architectural design, solar energy systems, crop growth models and determination of crop water requirement. In this research, twenty-four empirical global solar radiation models were evaluated using measured daily solar radiation and actual sunshine hours data for the years of 2001-2011 at Tabriz station located in the northwest of Iran. Statistical analysis showed that the most of these models presented good results in the study area. According to the relative percentage error (RPE) results, good agreement ( ) was obtained between the measured and calculated values of the solar radiation by use of nineteen numbers of the models. In contrast, the five rest models had not acceptable results. RPE values varied from 0.65% to -54.61% for the studied models. According to the ranking of the models performance, the RMSE, MBE, d and RPE values of the best model were 2.95, -0.18, 0.97 and 0.65, respectively. This model was recommended to use in the study region, where sunshine hours were