Layer-specific stress analysis of photovoltaic modules considering statistics-based hail diameters

Photovoltaic modules, which convert solar energy into electricity, have been utilized in various applications such as solar farms and building-integrated systems. However, hailstorms present critical challenges to maintain the high efficiency and structural safety during their operational lifespan. To evaluate the mechanical response of photovoltaic module under hail impact, the hail diameters of 30 mm and 50 mm in relation to the 95th and 99th percentiles of historical hail size distribution were selected to represent normal and extreme conditions. An improved numerical model was established considering the state equation, rate dependent and tension-compression asymmetry as well as the Smoothed Particle Hydrodynamics (SPH) method. The layer-specific stress characteristics are analyzed to investigate the stress evolution between material layers. The results show that the maximum stress under a 30 mm diameter hail exists on the upper and lower surfaces of the glass layer rather than the solar cell layer, since the soft encapsulant layer can absorb and dissipate impact energy to mitigate mechanical response. For the hail diameter of 50 mm, the increasing impact energy exceeds the energy dissipation capacity of the encapsulant layer. Therefore, the maximum stress of about 196 MPa mainly localizes in the solar cell layer and exceeds its ultimate strength. A further parametric analysis demonstrates that the reduction of elastic modulus of the encapsulant layer significantly decreases the maximum stress of solar cell layer by 72%, whereas the increase of encapsulant layer thickness only reduces stress by 21%, indicating that the elastic modulus of the encapsulant layer plays a more dominant role than its thickness in mitigating photovoltaic stress. The layer-specific stress analysis of photovoltaic panels under hail impact can provide insights for designing impact-resistant photovoltaic modules.