CdTe in thin film photovoltaic cells: Interventions to protect drinking water in production and end-of-life

Solar energy harvesting is a crucial technology in the transition away from fossil fuels. However, in order to make a renewable energy source truly sustainable, it is necessary to understand and mitigate broader impacts. At the Water-Energy Nexus lies the question of trade-offs between energy sources in terms of their water footprint, through water use or water contamination. The purpose of this work is to analyze CdTe thin film photovoltaic cells to evaluate interventions that can prevent contamination of drinking water. We focus on drinking water because of its relevance to the United Nation’s Sustainable Development Goal 6: clean water and sanitation. Thin-film PV cells use CdTe as a semiconductor material because of its advantageous band gap and high solar absorption efficiency. However, CdTe as well as cadmium and tellurium species can be toxic to aquatic and terrestrial ecosystems and pose serious health hazards to humans when present in drinking water. We propose a multiple criteria decision analysis (MCDA) that can be used by business leaders and politicians to aid in decision-making in regards to new interventions to protect drinking water. In this article we use a case study to demonstrate the use of the MCDA framework. The interventions analyzed in this review are regulation of recycling and disposal, bioreactors, and dye-sensitized solar cells. Protecting water supplies while increasing access to reliable electricity through low-cost solar is a critical path to meeting the UN Sustainable Development Goals as this renewable energy technology evolves.