Evaluation of irradiation measurements on tilted planes at PV systems in the Netherlands

Abstract

Monitoring data of Dutch PV systems in the field show lower values for the measured global irradiation in the array plane than expected from model calculatations. Since the locations of the PV systems contain obstacles, we expect that shielding of diffuse irradiation may cause the difference. For the Netherlands, the Perez model is the recommended model for calculating the diffuse array plane irradiation. We developed a correction to the Perez model to account for shielding of diffuse irradiation. We tested this model using 5 years of measured data of the PBB system in Utrecht. With the correction model, we could reduce the overestimation of the annual array plane irradiation from 9% to 2%. Both the Perez model and the correction model use an idealized description of the sky dome As a consequence, the correction model may overestimate the impact of the obstacles on the array plane irradation.