Sustainability evaluations on material consumption for terawatt-scale manufacturing of silicon-based tandem solar cells

High-efficiency silicon-based tandem solar cells will likely drive the push towards terawatt (TW) scale PV manufacturing on the pathway to net zero emissions by 2050. In this work, we provide a comprehensive analysis of material consumption and sustainability issues for future tandem solar cells. First, we analyse the material consumption and sustainable manufacturing capacity of a variety of potential candidates for the top cell in a silicon-based tandem cell. We show that III-V, CIGS and CdTe are not suitable to support TW-scale manufacturing. Perovskites thus present the most sustainable approach, as long as indium is not required in the cell structure. Next, we turn our attention to the silicon bottom cell architecture by comparing PERC, TOPCon and SHJ. Although tandem cells can generally reduce silver consumption relative to single junction silicon cells due to the more favourable J(MP)/V-MP ratio, the PERC cell architecture could allow for significantly reduced Ag consumption compared with both TOPCon and SHJ by relying on Al for the rear p-type contact. In order to drive a rapid shift towards TW-scale manufacturing, a rapid upscaling compared with the current production capacity is needed. The results presented herein highlight the need for careful consideration of sustainability issues when designing future high-efficiency tandem cells that will help the world mitigate the dangers of climate change.