Dynamic and probabilistic material flow analysis for circular economy strategies in the photovoltaic sector

The rapid expansion of solar photovoltaic (SPV) systems poses critical challenges to material supply security and waste management. Addressing these challenges require integrating circular economy strategies. This study develops a dynamic and probabilistic material flow analysis (MFA) to quantify the lifecycle material flows of crystalline silicon (c-Si) modules from 1998 to 2050, with waste projections extended to 2099. Three circular economy scenarios are evaluated, integrating the European Union Directive targets and strategies for reducing, reusing, and recycling. Uncertainty is explicitly addressed through Monte Carlo simulation, capturing variability in installed capacity projections, Weibull lifetime parameters, material composition, pre-operational losses, and recycling efficiencies. Portugal is used as a national-scale case study to demonstrate the applicability of the proposed methodology. Results indicate a cumulative material requirement of approximately 1.46 Mt by 2050 without circular strategies. Across low-, medium-, and high-circularity scenarios, both total material demand and the share of primary versus secondary raw materials vary substantially. Notably, scenarios incorporating reuse may increase primary material extraction due to reduced availability of secondary materials for manufacturing. Deterministic analysis suggests that full c-Si loop closure can be achieved between 2039 and 2041, depending on the scenario. However, probabilistic results reveal substantial uncertainty, with the probability of 100% Circular Material Use Rate (CMUR) in the period 2030–2050 among 53.7%, 43.6% and 68.6% under low, medium, and high circularity respectively. Sensitivity analysis identifies future c-Si’s deployment and lifetimes as the dominant drivers of circularity outcomes. This probabilistic MFA contributes with robust evidence to support circular economy policy design and infrastructure planning while opening avenues for further research.