Life Cycle Environmental Impact Assessment of Roofing-Based Monocrystalline Silicon Photovoltaic Systems

This study conducted a cradle-to-grave life-cycle assessment of a 1 kWp grid-connected building-applied monocrystalline silicon photovoltaic system installed on a public-building flat roof in Chizhou, Anhui Province, China. The assessment covered production, transport, 30-year operation and maintenance, and end-of-life recycling. ReCiPe 2016 Midpoint (H), IPCC AR6 100-year global warming potential characterization, cumulative energy demand accounting, and Monte Carlo simulation were applied to quantify environmental impacts, energy demand, carbon emissions, and parameter uncertainty. The system is expected to deliver 34,822 kWh/kWp of electricity over its service life. Gross life-cycle carbon emissions and cumulative energy demand, excluding recycling credits, were 1194.08 kg CO2-Eq/kWp and 4290.30 kWh/kWp, respectively. End-of-life material recovery provided avoided burdens of 773.11 kg CO2-Eq/kWp and 2309.84 kWh/kWp, reducing the net results to 420.96 kg CO2-Eq/kWp and 1980.46 kWh/kWp. Accordingly, the gross and net life-cycle carbon emission intensities were 34.29 and 12.09 g CO2-Eq/kWh, respectively. The gross and net Energy Payback Periods were 3.42 and 1.58 years, while the corresponding carbon payback times were 1.67 and 0.59 years. Production was the principal source of environmental burdens, whereas recycling substantially improved the overall performance. Monte Carlo simulation indicated coefficients of variation of 3.59–5.28% for the assessed production-stage indicators. These findings highlight the importance of decarbonizing upstream electricity, reducing material burdens from aluminium, copper, and electronic components, and improving end-of-life recovery pathways.