The view‐factor effect shaping of I‐V characteristics

Abstract

AbstractThe diffuse radiation collected by PV modules is coupled with a view‐factor of the module to sky, which varies across the module surface in multiple‐row installations. The view‐factor variation inflicts current mismatch between the module strings by virtue of the nonuniform solar flux absorbed by the module's cells, leading in turn to an overall reduction in performance. The following study establishes a theoretical framework for predicting the step‐wise properties of the module I‐V curve following the current mismatch induced by the view‐factor. To illustrate the steps pattern, synthetic I‐V curves are derived by using the 5‐parameter PV cell single‐diode model in conjunction with 3 additional parameters that account for the cell's avalanche breakdown. We investigate the steps pattern as well as the power losses incurred by the view‐factor by simulating different types of PV deployments over a range diffuse radiation rates. For a tilted module installed on a horizontal plane, for instance, the study predicts a reduction in power ranging 2.8% to 25%, depending on the precentage diffuse radiation on the site in question.