Life Cycle Analysis of Metals in Emerging Photovoltaic (PV) Technologies

The potential release of toxic metals used in emerging photovoltaic (PV) technologies has raised concerns about the safe use of these new types of solar cells. In this study, we address this concern by a life cycle toxicity... [ view full abstract ]

The potential release of toxic metals used in emerging photovoltaic (PV) technologies has raised concerns about the safe use of these new types of solar cells. In this study, we address this concern by a life cycle toxicity analysis of six metals (Cd, Cu, Pb, Ni, Sn and Zn) that are commonly used in emerging PV cells. To estimate the potential metal release from damaged cells we introduce a new model that incorporates field conditions (crack size, time, thickness of top encapsulation glass), and physiochemical properties (diffusion coefficient and solubility product) of metal compounds. The results show that the use phase toxicity of Cu and Pb can be higher than that of the extraction phase. Thus, we propose precautionary metal loss limits for the design of emerging PVs to control toxic impacts during the use of PVs.  In addition, we analysed a case study to reduce the metal toxicity in emerging PV technologies such as perovskite, copper zinc tin sulphide, and quantum dot solar cells. We found that CdS (compared to ZnO and SnO₂) and PbS (compared to MAPbI₂ and CZTS) are less toxic alternatives for electron selective layer and light absorber, respectively. Finally, in comparing the toxicity of the emerging PV devices to today’s coal power plants, we found the metal emissions from solar PV to be several orders of magnitude less than the emissions from coal.