Beyond static cross-sectional views: unraveling the spatiotemporal evolution of the carbon footprints of China's mainstream photovoltaic systems

Conventional life cycle assessments often lack temporal dimension and spatial variation. This study incorporates temporal dynamics, spatial heterogeneity, and technological diversity to reveal the spatiotemporal evolution of the carbon footprints of China's PV systems, quantify the mitigation effects of key drivers, and assess the PV systems' cumulative net emission reduction benefits. The results show that the carbon footprint of 1 kWp annually installed PV system declined from 1481.34–1837.15 kg CO 2 -eq in 2011 to 1060.98–1271.45 kg CO 2 -eq in 2022. Technological progress contributed almost three times that of grid decarbonization to carbon mitigation in the module manufacturing stage. Over the same period, the life cycle carbon emission per kWh generated from annually installed PV also decreased, from 70.53–75.39 g CO 2 -eq to 50.52–52.17 g CO 2 -eq, with substantial inter-provincial variation. Due to the continued influence of legacy systems installed in earlier years with higher embodied emissions, the average carbon intensity of the in-operation PV fleet remained higher than that of newly installed systems. In terms of net mitigation performance, China's operating PV fleet reached a structural turning point in 2017, when cumulative emission reductions first exceeded cumulative emissions. Scenario analysis indicates that a synergistic pathway combining efficiency improvements with grid decarbonization is critical for optimal mitigation outcomes. These results highlight the need for China to boost PV manufacturing and generation efficiency while optimizing their spatial layout. The framework developed herein can offer multi-dimensional, dynamic perspectives to underpin differentiated policy design.