Climate-Driven Thermal Degradation and Life-Cycle Global Warming Potential of Photovoltaic Systems Under Increasing Heatwave Exposure

This study evaluates how future heatwave exposure affects photovoltaic (PV) thermal stress, degradation, service life, lifetime generation, and life-cycle global warming potential (GWP) in Stuttgart, Germany. A fixed-reference 1 kWp crystalline-silicon system was linked to NEX-GDDP-CMIP6 projections, a PVGIS-informed daily module-temperature proxy, temperature-only Arrhenius stress, and two replacement-accounting treatments. Under SSP5-8.5 in 2081–2100, heatwave frequency increased from 1.08 to 6.68 events yr−1 and heatwave days from 4.78 to 49.87 days yr−1. The modeled degradation rate rose from 0.66% to 1.27% yr−1, reducing scenario-conditioned service life from the 30-year cap to approximately 16 years and single-module lifetime generation by about 45%. After correcting the IEA-PVPS reference-energy reconstruction, GWP increased from 35.07 to 53.89 g CO2-eq kWh−1 with integer replacement and to 50.95 g CO2-eq kWh−1 with residual-service-life allocation. Under the primary 30 °C/3-day heatwave definition, heatwave-day changes accounted for 95.9% of the modeled late-century increase in the calibrated temperature-only stress proxy; the corresponding signed attribution under model-specific historical P90 thresholds was 106.5%, showing that the exact percentage is definition-sensitive. The results represent a climate perturbation of a contemporary LCA reference, not a prospective assessment of future PV technology.