The rapid expansion of photovoltaic (PV) solar parks in fire-prone rural landscapes has raised concerns regarding the vulnerability of renewable energy infrastructure to wildfires, particularly in Mediterranean regions where large fires frequently affect agroforestry areas. Despite the increasing deployment of PV systems, their behaviour under wildfire exposure remains poorly documented, particularly regarding ignition potential, thermal degradation and implications for vegetation management. This study investigates the vulnerability of photovoltaic panels to wildfire exposure through laboratory experiments, analytical modelling and full-scale validation tests, aiming to support the development of passive protection criteria for large-scale solar parks.

Controlled cone calorimeter experiments were conducted on commercially available PV modules to identify critical heat-flux thresholds associated with progressive degradation. A simplified heat-transfer model was used to estimate minimum separation distances between panels and surrounding vegetation under different fuel and topographic conditions. The results indicate that PV panels (glass-glass type) exhibit relatively high resistance to ignition under wildfire exposure and that maintaining limited vegetation clearance may significantly reduce ignition risk.

Six cone calorimeter tests quantified the thermal degradation of PV modules under increasing heat exposure. The earliest signs of degradation were associated with carbon monoxide emissions at approximately 8.36 kW/m², while visible smoke was released at approximately 16.77 kW/m². Ignition was only observed when incident heat flux exceeded approximately 18.20 kW/m². Based on these results, a vulnerability function relating incident heat flux to panel response was established. The analytical model predicted minimum safety distances across different vegetation and slope scenarios, ranging from approximately 0.6 m in grassland and 0º slope to 4.1 m in dense shrubland and forest on steep slopes (40º).

Full-scale validation experiments were conducted to reproduce realistic wildfire exposure conditions, including direct flame-front exposure and fires developing beneath the panels. Exposure to flames between 0.5 m and 3.5 m in height caused limited material degradation and no sustained combustion. Direct flame impingement on the underside of the panels produced localised charring and deformation, but combustion self-extinguished once the external heat source was removed. Mass loss remained below 2% in the most severe tests, confirming the limited combustibility of the PV modules.

The findings indicate that glass-glass photovoltaic panels exhibit limited susceptibility to sustained combustion during wildfire exposure and do not significantly contribute to fire propagation when appropriate fuel management practices are implemented. The results support the development of guidelines for fuel management and infrastructure design for photovoltaic parks in wildfire-prone regions.

Acknowledgement: This research was funded by LightSource BP and by the Fundação para a Ciência e a Tecnologia, I.P. (FCT, https://ror.org/00snfqn58) under Grant (Funder Grant number and/or Grant DOI). For the purpose of Open Access, the author has applied a CC-BY public copyright license to any Author‘s Accepted Manuscript (AAM) version arising from this submission.