Carbon offset potential of rooftop photovoltaic systems in China

As a promising tool for mitigating carbon emission, rooftop photovoltaics have attracted worldwide attention. This study examines the carbon offset potential of rooftop photovoltaics in 31 provinces in China. The future trends of carbon offset potentials over the lifetime of rooftop photovoltaic systems are investigated. The findings reveal that the carbon offset potentials vary significantly across different regions in China due to the combined effects of variations in climate conditions and the energy mix for electricity generation. The northern regions possess significantly higher carbon offset potentials than the southwestern areas. In 2021, the annual total carbon offset potential ranged from the lowest at −2.0 kg CO2/m2 in Tibet to the highest at 169.3 kg CO2/m2 in Beijing. The projected future trends indicate that Beijing and Tibet will respectively maintain their highest and lowest carbon offset potential rankings. Most provinces are projected to witness decreasing carbon offset potentials. In terms of the carbon offset potential over the lifetime of rooftop photovoltaics, the northern regions − Beijing, Tianjin and Inner Mongolia − rank the top three. Not only can these findings serve as reference for developing targeted policies for carbon mitigation in China, the methodology of this study can also be applied in other places to determine their carbon offset potentials of rooftop photovoltaics.