Optical Characterisation of PV Glasses with Varying Antimony Contents

Antimony pentoxide is often added during the production of rolled solar glass to reduce light absorption in the near-infrared spectrum. However, this compound is toxic, poses environmental risks, and restricts the recycling of antimony-containing solar glass. This study examines the optical properties of solar glasses with varying antimony concentrations to determine how much the content can be reduced without compromising the optical performance of PV glass. An antimony-free float glass was compared with four rolled (textured) glass samples containing antimony levels from 10 ppm to 1240 ppm. Optical quality was assessed through transmittance, reflectance, and IAM measurements. These results were then used to calculate the linear absorption coefficient and to simulate PV module performance with SmartCalc.Module. The rolled glass samples showed better transmittance than the float glass, but no advantage in reflectance. IAM performance was slightly higher for the rolled glasses, though this was due to the textured surface rather than the antimony content. When normalized for thickness using the linear absorption coefficient, the rolled glasses showed lower absorption than the float glass. Surprisingly, no clear correlation was found between antimony concentration and absorption behaviour. Overall, the superior optical properties of the rolled glasses translated into a rated energy yield about 1% higher than that of the float glass. It is important, that it is difficult to generalise these results without knowing the exact chemical composition or the production process of the glasses. However, a key finding is, that high-quality rolled solar glass can be produced without the need of adding antimony.