Energy and Environmental Sustainability Assessment of Photovoltaics Transition toward Perovskite–Perovskite Tandems from the Attributional and Consequential Perspectives
Xueyu Tian, Fengqi You
Abstract
In pursuit of photovoltaic (PV) technologies of high-efficiency and low production cost, all-perovskite tandem solar modules have been gauged with a great potential for widespread PV deployment. In this study, we conduct a holistic life cycle assessment (LCA) using both attributional and consequential approaches. The attributional LCA results show substantial decreases in both cumulative energy demand and greenhouse gas emissions for the shift from benchmark silicon PVs to the emerging yet promising perovskite–perovskite tandems. From a consequential perspective, much silicon metal is avoided due to the transition, of which the indirect consequences dominate the consequential environmental impacts. Attributional LCA helps identify the hotspot components throughout life cycle stages, the market changes of which are likely to dominate the consequential life cycle environmental impacts as well. However, consequential LCA provides complementary insights that cannot be gained in attributional LCA, despite the obstacle in data acquisition and relatively low data quality. The benchmark silicon PV demonstrates higher global warming potential and cumulative energy demand than the tandem stack by a factor of around three. Silicon is identified as a hotspot in the fabrication of benchmark silicon PVs in attributional LCA, and we find that the activities associated with its market, including the domestic production and importation of aluminum alloy, contribute up to 90% share of the consequential environmental scores. In addition, the price elasticity of supply and demand in the silicon metal market is identified as the most influential factor for both GWP and ReCiPe end-point environmental scores, resulting in up to 37.6 and 26.6% deviations from the corresponding values.