A comparative life cycle assessment of silicon PV modules: Impact of module design, manufacturing location and inventory

Abstract

Life Cycle Assessments (LCA) of single-crystalline silicon (sc-Si) photovoltaic (PV) systems often disregard novel module designs (e.g. glass-glass modules) and the fast pace of improvements in production. This study closes this research gap by comparing the environmental impacts of sc-Si glass-backsheet and glass-glass modules produced in China, Germany and the European Union (EU), using current inventory data. Results show lower potential environmental impacts for glass-glass compared to glass-backsheet modules and lower impacts for production in the EU and Germany compared to China for most impact categories. Concerning climate change, glass-backsheet (glass-glass) modules produced in China, Germany or the EU are linked to emissions of 810 (750), 580 (520) and 480 (420) kg CO2-eq/kWp, respectively. This corresponds to CO2-eq emission reductions of 30% for German and 40% for European production compared to Chinese production, and 8–12.5% reduction in glass-glass compared to glass-backsheet modules. Carbon intensity of produced electricity, excluding balance of system (BOS), amounts to 13–30 g CO2-eq/kWh, depending on production location and electricity yield calculation method. A warranty-based yield calculation method shows the influence of different lifetime electricity yields of glass-glass and glass-backsheet modules on the potential environmental impacts. This study identifies module efficiency, energy requirements, silicon consumption and carbon-intensity of electricity during production as significant levers for future reductions of environmental impacts. It emphasizes the importance of up-to-date inventories and current modelling of electricity mixes for representative LCA results of PV modules. Lastly, this paper argues that more differentiated methodological guidelines are needed to incentivize the development of sustainable module designs.