Model-based province-level projections of residential PV lifecycle emissions under trade-old-for-new policies in China (2020–2050)

Residential photovoltaic (PV) systems are central to China's decarbonization, yet aging assets threaten long-term mitigation. This study quantifies the impact of Trade-Old-for-New (TON) policies on the lifecycle carbon outcomes of residential photovoltaic systems across China from 2020 to 2050. A province-level modeling framework is employed, projecting PV adoption, tracking retirements via Weibull lifetimes, and computing lifecycle emissions with dynamic emission factors and recycling credits, spatial dynamics are summarized with standard deviational ellipse metrics, and scenarios compare complete replacement, progressive replacement, and static retirement. Results reveal pronounced heterogeneity, eastern provinces contribute over 60 % of cumulative reductions; Hebei and Shandong achieve up to 789 % and 232 % greater reductions under complete replacement versus a static retirement baseline, and spatial coverage expands by 134.6 % by 2050 as TON diffuses westward. Recycling accounts for 30–35 % of lifecycle savings under TON, while its absence would lower national mitigation by over 30 %. The novelty lies in endogenizing TON with certified recycling within the lifecycle boundary, delivering spatiotemporal trajectories that isolate the incremental mitigation from replacement policy. The findings prioritize provinces with aging fleets and high grid-emission factors and suggest allocating about a significant portion of policy support to certified recycling, providing actionable levers for carbon neutrality pathway.