Sustainability outlook for leading silicon photovoltaic technologies from 2023–2034 in Europe

As Europe progresses toward a greener future, the years ahead bring expectations of widespread, large-scale photovoltaic (PV) deployment. Presently, mainstream silicon PV is transitioning away from the passivated emitter rear cell (PERC) architecture towards higher efficiency cell designs: tunnel oxide passivated contact (TOPCon) and silicon heterojunction (SHJ). With net-zero deadlines looming, there is an urgent need for comprehensive sustainability investigations into minimizing the environmental impact of large-scale actions before suffering avoidable consequences. Using life cycle assessment, these three silicon technologies are investigated and compared, finding SHJ to have the lowest global impact, closely followed by TOPCon. Both have lower impacts than PERC for 15 of 16 investigated environmental impact categories, including climate change (−9.9% and −12.1%, respectively), but increased metal use (+29.5% and +13.0%, respectively). A hotspot analysis identifies research opportunities for reducing environmental impacts such as material innovation through substituting silver (metallization) and ethylene vinyl acetate (encapsulant), or, more broadly, improving process efficiency and integrating more renewables into the electricity mix. The environmental impact is further evaluated to consider technological developments and evolving electricity mixes to the year 2034, showing the impacts of SHJ and TOPCon are reduced by >10% for all six identified high-value impact categories. These are then used to model European PV deployment between 2023 and 2034, considering various manufacturing scenarios, which show that this could result in climate change emissions of <0.41 Gt CO2 eq., though implementation of the Net-Zero Industry Act could reduce this to 0.31 Gt CO2 eq. Finally, sensitivity analysis is conducted to investigate uncertainty associated with modeling future impacts, comparing the 2024 and 2025 International Technology Roadmap for Photovoltaics. The sensitivity analysis results provide additional confidence in the findings of the initial comparison and support the conclusion that SHJ technology has, and will continue to have, the lowest environmental impact of the three investigated technologies.