Life-cycle assessment of multi-crystalline photovoltaic (PV) systems in China

Abstract

This study performs a life-cycle assessment for a photovoltaic (PV) system with multi-crystalline silicon (multi-Si) modules in China. It considers the primary energy demand, energy payback time (EPBT), and environmental impacts, such as global warming potential and eutrophication, over the entire life cycle of the PV system, including the upstream process, ranging from silica extraction to the multi-Si purification, the midstream process, involving crystalline silicon ingot growth and wafering; and the downstream process, consisting of cell and module fabrication. The data were collected with recommendations provided by the ISO norms and acquired from typical PV companies in China. The results show that the most critical phase of life cycle of Chinese PV system was the transformation of metallic silicon into solar silicon, which was characterized by high electricity consumption, representing most of the environmental impact. The other electricity generation systems were compared to PV. Considering that Chinese electricity is mainly produced by coal-fired power plants, the installation of multi-Si PV systems is recommended over exporting them from China. Furthermore, being higher solar radiation areas, areas in western China, such as the Tibet Autonomous Region, northeastern Qinghai, and the western borders of Gansu, are best suited for the installation of the PV systems even if the long distance of transportation. Finally, recommendations were provided with respect to the sustainable development of the Chinese PV industry and environmental protection.