Potential for Recycled Silicon Solar Cells as Feedstock for New Ingot Growth

ABSTRACT This paper investigates, by modeling, the potential for high‐value recycling of silicon wafers recovered from end‐of‐life PV modules. Technology for PV module recycling is making steady progress, both at recycling companies and R&D institutes, and it is possible that as a result, soon a stream of wafers or wafer fragments recovered from waste modules will become commercially available. Recycling the silicon for manufacturing of new PV modules is an opportunity both for reduction of cost and reduction of environmental footprint of PV. In this paper, we analyze possibilities for recycling of wafer fragments as feedstock for new silicon ingot growth . This could save up to about 0.16 kWh/Wp energy for production of the new PV system. Compared with lower value applications of the recovered silicon, the potential value and energy savings when used as feedstock for ingot growth are considerably higher. This paper presents the possibilities and challenges for recycling wafer fragments from the point of view of dopant type and resistivity control, and mitigation of the impact of recombination activity from possible increased impurity levels or related to boron. Because in current PV production a rapid transition to n‐type wafer doping is taking place, the paper also considers the question what can be done with p‐type doped recycled wafer material. We illustrate how application for perovskite–silicon tandem cells helps to mitigate possible performance loss from metallic impurities or boron. The application in tandem cells is perhaps the only realistic approach to make economically worthwhile use of recycled B‐doped silicon as feedstock for silicon ingot growth.