Material intensity and carbon footprint of crystalline silicon module assembly over time

Abstract

The growing solar photovoltaic (PV) installations have raised concerns about the life cycle carbon impact of PV manufacturing. While silicon PV modules share a similar framed glass-backsheet structure, the material consumption varies depending on module design, manufacturer, and manufacturing year, leading to varying carbon emissions. However, current life cycle assessment (LCA) studies and public inventory databases of silicon PVs lack an assessment of the variability in commercialized solar module designs and their potential impact on module reliability and carbon footprint. The present study aims to address this research gap by providing a temporal analysis of aluminum and glass intensity in crystalline silicon modules produced from 2006 to 2021. The material inventory data is obtained from specification sheets of 167 crystalline silicon modules produced by 31 manufacturers. Subsequently, we use the collected material inventory to estimate the carbon footprint of manufacturing silicon modules in multiple countries over the past decade. The results reveal a 30% reduction in the aluminum intensity used for frames from 2010 to 2021, while the solar glass thickness remains relatively constant. Additionally, the comparison among manufacturer tiers indicates that more reliable modules tend to use more materials for module production. Moreover, the comparative life cycle assessment of modules manufactured in various countries demonstrates a significant impact of local electricity mixes on the carbon footprint of module manufacturing. Modules manufactured in China exhibit the highest carbon emissions, followed by Malaysia (4–9% lower than China), South Korea (15–16% lower than China), the US (17–18% lower than China), Thailand (19–21% lower than China), Turkey (18–21% lower than China), and Vietnam (25–30% lower than China). Overall, the present study highlights the importance of up-to-date data on material inventory and local electricity mixes in evaluating the environmental impacts associated with PV manufacturing. Lastly, we advocate for integrating the variability of module designs and manufacturing locations within low-carbon solar module criteria and guidelines, recognizing the importance of adaptability in achieving sustainable solar manufacturing.