Investigating the fire dynamics of mounted PV weathering effects and material changes.

Solar photovoltaic (PV) systems constitute approximately 37% of global renewable energy capacity, yet their fire safety under environmental degradation remains inadequately understood. PV backsheets serve as the primary interface between external fire sources and modules, making their long-term fire performance critical for system safety. This study systematically quantified flame spread behavior on weathered PV backsheets. Two commercial backsheet types underwent accelerated weathering for up to six weeks, followed by comprehensive characterization using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile testing. Fire performance was assessed using a time-to-marker (TTM) methodology to measure flame propagation rates. Six-week weathered samples exhibited a 46% faster flame spread, demonstrating significant degradation in fire resistance. Chemical analysis revealed polymer chain scission and formation of degradation products, while mechanical testing showed up to 18% reduction in tensile strength. These findings highlight critical gaps in current safety standards and demonstrate the importance of incorporating weathering effects into PV fire safety assessments for long-term system reliability.