Understanding the impact of sky diffuse irradiance on curved photovoltaic modules

Modules utilized in vehicle-integrated photovoltaics (VIPV) have particularities that make them differ from standard PV modules. These particularities are related to their curvature and operating conditions (changing locations, orientations, etc.) and they need to be addressed in the characterization. A vital characterization test is the angular response test, which allows obtaining the electrical response of the module under different angles of incidence and orientations. Results from these tests on real commercial modules presented some dispersion, which is related to diffuse irradiance. Two outdoors experiments involving a programmable dual-axis tracker were conducted to verify its impact: the first one was made with a 1D highly curved module under cloudy sky conditions to identify the effect of diffuse irradiance on such modules and the second experiment assessed the angular response of a 2D commercial curved module under clear sky conditions. Based on the findings, recommendations are given to minimize dispersion in outdoors angular response measurements.