Integrating rooftop photovoltaics into urban rail infrastructure: A life cycle assessment with environmental impacts and localization insights

The global energy transition increasingly prioritizes rooftop photovoltaic (PV) applications, particularly in urban environments, supported by incentive schemes and regulatory frameworks. Assessing the environmental performance of emerging PV technologies is critical for ensuring sustainable development and maximizing long-term benefits. This study conducts a Life Cycle Assessment (LCA) of a 1956.15 kilowatt-peak (kWp) grid-connected rooftop PV system utilizing Passivated Emitter and Rear Cell (PERC) technology, slated for installation on the workshop building of a rail transit facility in Istanbul, Türkiye. The assessment encompasses the entire life cycle, including module manufacturing, balance of system (BoS) components, installation, operation/use, and end-of-life (EoL) stages. The results indicate that PV module production constitutes the primary environmental hotspot. Under the baseline scenario, the system's Global Warming Potential (GWP) is estimated at 55.1 g of carbon dioxide equivalent per kilowatt-hour (g CO₂ eq./kWh), with an anticipated annual avoidance of approximately 867.26 metric tons of CO₂ eq. relative to 2025 grid electricity. Notably, this study is among the first to quantitatively evaluate the benefits of supply chain localization for PV systems in Türkiye, demonstrating a 30.8 % GWP reduction through domestic manufacturing. Despite projected increases in renewable energy within the Turkish grid, rooftop PV remains a low-carbon alternative, with estimated GWP reductions of 85.5 % and 81.7 % by 2030 and 2035, respectively. However, other environmental burdens, such as resource use, minerals and metals (ADP-ultimate) during the manufacturing phase, are also warrant attention. A dedicated review of solar PV deployment in rail systems-rarely addressed in LCA literature-provides actionable insights for policymakers and urban planners, reinforcing the interdisciplinary relevance of the findings.