Relative angular response characterization in VIPV

VIPV surfaces operate predominantly under non-normal irradiance conditions, underscoring the importance of understanding their angular performance for energy modeling in this technology. However, vehicle surfaces require double curvature for aesthetic and aerodynamic reasons, causing their angular response to deviate from conventional flat plates. This paper addresses the study and characterization of the angular performance of curved VIPV surfaces. A quasi-commercial VIPV module was measured indoors using a collimated beam solar simulator and a two-axis rotating structure. Furthermore, outdoor characterization under real sunlight was also performed by installing the VIPV module on a two-axis tracker. The solar tracker control has been programmed to introduce fixed misalignments between the aperture plane of the assembly and the solar disk. This feature allows measuring the IV curve of the modules under various angles of incidence, limited only by the angular range of the tracker (+/- 60 degrees). The two-dimensional angular responses measured both indoors and outdoors are compared and discussed. In addition, simulations based on optical ray-tracing to determine the irradiance distribution on the module surface and a SPICE electrical model to calculate the IV curves were conducted and validated with the experimental results. The opto-electrical models were then used to explore several cell interconnections and analyze the impact on the angular response.