Sustainability of photovoltaic technologies in future net-zero emissions scenarios

Photovoltaic installed cumulative capacity reached 849.5 GW worldwide at the end of 2021, and it is expected to rise to 5 TW by 2030. The sustainability of this massive deployment of photovoltaic modules is analysed in this article. A literature review, completed with our own research for emerging technologies has been carried out following life cycle assessment (LCA) methodology complying with ISO 14040 and ISO 14044 standards. Different impact categories have been analysed for five commercial photovoltaic technologies comprising more than 99% of current market (crystalline silicon ~94% and thin film ~6%) and a representative of an emerging technology (hybrid perovskite). By using data from LCA inventories, a quantitative result for 15 impact categories has been calculated at midpoint and then aggregated in four endpoint categories of damage following ReCiPe pathways (global warming potential, human health damage, ecosystems damage and resources depletion) in order to enable a comparison to other renewable, fossil fuel and nuclear electricity production. In all categories, solar electricity has much lower impacts than fossil fuel electricity. This information is complemented with an analysis of the production of minerals with data from the British Geological Survey; the ratio of world production to photovoltaic demand is calculated for 2019 and projected to 2030, thus quantifying the potential risks arising from silver scarcity for c-Si technology, from tellurium for CdTe technology and from indium for CIGS and organic or hybrid emerging technologies. Mineral scarcity may pose some risk for CdTe and CIGS technologies, while c-Si based technology is only affected by silver dependence that can be avoided with other metals replacement for electrodes. When the risks grow higher, investment in recycling should boost the recovery ratio of minerals and other components from PV module waste.