Pollutant payback time and environmental impact of Chinese multi-crystalline photovoltaic production based on life cycle assessment

A Life Cycle Assessment (LCA), using the end-point damage model (CEDM) of impact assessment, was conducted, to analyse the environmental impacts and pollutant payback times of photovoltaic production, including solar-grade silicon, silicon wafers, silicon solar cells and photovoltaic panels, in China. The inputs and outputs were obtained using site investigation, questionnaires, and field monitoring, and a method of aggregating the data into an industry-level database was established. The production yield of the studied samples accounted for an average 66% of the national yield in 2013. The results showed that the respiratory-inorganics and fossil-fuel categories contributed the most impact, because of the large electricity consumption required. Recent technological advances in raw material reduction and energy savings are the primary pathways to decreasing the environmental impacts. The environmental impact of a photovoltaic system is equivalent to 4.5% of that of the impact of the current coal-based electrical power system in China. The pollutant payback times of chemical oxygen demand, chloride, fluoride, ammonia gas, nitric oxide, sulfur dioxide, hydrogen chloride, hydrogen fluoride and carbon dioxide are 5.11, 1.02, 25.1, 8.01, 0.831, 0.784, 0.716, 1.12 and 0.884 years, respectively, indicating that most of the pollutants could be paid back within the expected lifetime of a photovoltaic system. Therefore, installing photovoltaic systems could reduce not only the consumption of non-renewable energy, but also the emitted pollutants, decreasing the environmental impacts of electricity generation.