THE EFFECT OF DIFFERENT SKY TEMPERATURE MODELS ON THE ACCURACY IN THE ESTIMATION OF THE PERFORMANCE OF A PHOTOVOLTAIC MODULE

Abstract

This paper considers the effect of different sky temperature models on the accuracy in the estimation of the performance of an open-rack-mounted photovoltaic (PV) module. It is found that, for the same ambient conditions, the temperatures of the PV module calculated using individual sky temperature models deviate, on average, by about 4 °C from the measured one. Further, this causes an error in the estimation of the power output of the PV module that can not be ignored when a precise performance analysis is required. The effect of different sky temperature models is estimated using a heat balance equation of the PV module, where the term related to long-wave radiation heat exchange between the sky and the PV module’s upper surface is significantly affected by the sky temperature. Based on comparisons between the calculated and measured temperatures of the PV module considered, sky temperature models, providing the best results, are singled out. Furthermore, it is pointed out which models have the largest deviations.