Comparison of the environmental impacts of perovskite/silicon tandem and silicon heterojunction photovoltaic modules using a parameterised approach

Photovoltaic technology is pivotal in the global energy transition, and while emerging technologies promise better performance, their environmental impacts must be carefully evaluated. Among these, perovskite/silicon (PSK/Si) tandem technology has garnered significant attention. However, existing Life Cycle Assessment studies on PSK/Si tandems exhibit significant uncertainty, complicating comparisons of environmental performance across different technologies. This study offers a comparative analysis of the environmental impacts of different PSK/Si tandem modules and silicon heterojunction (SHJ) modules, explicitly incorporating multiple sources of uncertainty to ensure a more comprehensive and reliable comparison. Uncertainty sources include uncertainty in 21 variable parameters (e.g., lifetime and power conversion efficiency), differences between two-terminal and four-terminal tandem architectures, and alternative degradation scenarios of tandem modules. Propagating these uncertainties through parameterised models allows for a direct comparison of the resulting distributions of environmental impacts for tandem and SHJ modules. For example, in the case of modules manufactured in France, PSK/Si tandems show climate change impacts ranging from 5.5 to 8.7 g CO 2 eq/kWh, whereas SHJ modules range from 6.3 to 9.4 g CO 2 eq/kWh. To streamline comparisons, global sensitivity analysis identifies the key parameters contributing most significantly to output uncertainty. These insights inform the development of simplified arithmetic models that require only a limited set of key inputs. Such models enable rapid, accurate estimation of environmental impacts for both PSK/Si tandem and SHJ modules, facilitating efficient and reliable comparisons. Overall, this work enhances understanding of the environmental performance of PSK/Si tandem and SHJ modules and supports strategies to improve their sustainability, thereby guiding strategic decision-making in the renewable energy sector.