Current mismatch in PV panels resulting from different locations of cells in the panel

Abstract

The incident solar radiation on a photovoltaic panel (collector) consists of the direct beam, diffuse and reflected radiation. The amount of the diffuse radiation on the collector depends on the view factor of the collector to sky and the sky irradiance distribution. The amount of the reflected radiation on the collector from the ground and from neighboring collectors depends of the view factors of the collector to ground and between collectors. The view factors vary with the distance along the width of the collector and hence, the diffuse and reflected incident radiation on solar cells in different rows (strips) of the PV panel vary and resulting in current mismatch between cells in the different rows. The view factor of a collector is an average value, whereas the view factor of cells in a row is a local view factor depending on the location of cells along the collector width. The present work develops analytical expressions for the view factors to sky and to ground and between collectors for different strips along the width of the PV panel, including the front and rear sides of the collector. The view factor expressions were developed for deployment of collectors in multiple rows is solar fields. The effect of inclination angle, distance between the collectors, collector width and collectors raised above the ground on the view factors were demonstrated numerically. The difference in view factor to sky between the first and the third strip, in a three strip collector, may be in the order of tens of a percent.