Advanced characterisation of photovoltaics for hail resistance

Abstract

Climate change is intensifying severe weather events, especially in alpine environments where hailstorms are more frequent and intense. In particular, hail damage seriously affects photovoltaic systems. The severity of hailstorms as well as impact responses are important factors in mitigating loss, so the first research area that needs to be addressed is the resistance of photovoltaic modules to hail. According to IEC 61215 standard, a PV module should resist at the minimum to the impact of a hailstone of 25 mm launched at 80 km/h, while the Swiss VKF standard demands a minimum of 30 mm, practically making it 40 mm or more. The hail test stand is being enhanced to support larger diameters and higher speed, enabling module manufacturers to assess their products with adequate safety margins. Larger ice ball requires evaluating sample preparation, repeatability, representativity, and the ability to handle high speeds and masses in order to minimise uncertainty in impact energy. In this preliminary study, ice ball samples with diameters of 25, 40, and 70 mm were tested on a Hopkinson bar at speeds from 20 to 140 m/s and temperatures from −5 °C to −20 °C. The effects of impact velocity, loading rate, and impact time were examined. Finally, the first tests on PV modulus with large ice ball and high velocity are presented.