Carbon footprints of solar panels in China provinces based on different production and waste treatment scenarios

The ambitious goal of reaching net-zero worldwide has promoted the development of renewable energy, but the seemingly green energy also requires massive resource and energy consumption during its lifecycle. Especially for China, the top solar panel manufacturer and user, the environmental impacts of solar systems should be concerned in the long-term, particularly in the field of retired photovoltaic (PV) recycling. However, provincial carbon footprints of solar panels based on different production and waste treatment techniques have not been estimated before, including the accumulated and potentially reduced amount of carbon footprints (compared with designed optimal scenarios) in China. This research aims to calculate the total and reduced carbon footprints of solar panels by using the provincial electricity generation data of PVs in China. Results show that the national accumulated carbon emissions of installed panels from 2011 to 2035 would exceed 5 Gt CO2eq by 2060. With advanced production technology and efficient waste treatment, the emissions could be significantly reduced by 50% for the whole lifecycle and 36% for recycling. Although large emission variations existed among provinces, the dominant emission sources shifted from the northwest to eastern regions of China in recent years. Our study provides fundamental guidance to the governmental regulations of waste PVs as well as technological development of recycling treatment scenarios.