Design and light transmittance distribution measurements of semitransparent c-Si PV modules for agrivoltaic systems

Abstract

Crystalline silicon (c-Si) photovoltaic (PV) modules dominate agrivoltaic (AV) applications. However, they are opaque in the photosynthetically active radiation range. The shading induced by the PV modules could be partly alleviated by using semitransparent PV modules and by enhancing the distribution of the transmitted light. A clear research gap lies in the development of semitransparent c-Si PV modules with optimized haze materials to enhance the light distribution at the crop canopy. In this work, eight semitransparent c-Si PV modules with cells in checkerboard and inter-string patterns, for glass-glass and various glass-transparent backsheets, were fabricated incorporating different encapsulants. Outdoor measurements and ray tracing-based simulations of the transmitted light intensity distribution through the PV modules were carried out and compared. In addition, haze and Hortiscatter measurements were performed to determine the light-scattering behaviors of the PV module structural layers. Findings showed that PV modules with transparent backsheets can enhance the light distribution in AV systems, while the fluorine-based backsheet showed higher light scattering than the non-fluorine one. Transmitted peak light intensity for modules with EVA encapsulant were higher than TPO while the distribution behind the PV modules was less uniform for the former. The simulations showed good agreement with measurements, with a maximum RMSE of 10%. Extended damp heat reliability tests showed highest susceptibility of the non-fluorine based backsheet modules to moisture ingress. In essence, this work proposes a new approach for developing, assessing and optimizing the light intensity distribution through semitransparent PV modules tailored for AV applications.