A research group from Universitat Politècnica de Catalunya (UPC) in Spain has conducted conducted a cradle-to-gate life cycle assessment (LCA) of eight PV panel types across three generations and has found that tandem technologies demonstrate improved environmental performance over silicon-based systems, although they require long lifetimes and low degradation to deliver clear sustainability advantages.

“Perovskite-silicon tandem technologies have shown a reduced environmental impact compared to current dominant silicon-based cells,” corresponding author Julia Otero told pv magazine. “Conversion efficiencies over 30% in lab-scale, though not yet achieved at an industrial scale, significantly contribute to these positive environmental impacts. However, when compared to thin-film technologies such as cadmium telluride (CdTe) and copper, indium, gallium and selenide (CIGS), these tandem models show a higher environmental footprint. On this point, we highlight that the absorber layers of thin-films feature a 20 to 80 times lower thickness than traditional silicon wafers. This low material consumption directly drives the environmental performance of thin-films.”

The harmonized life cycle assessment (LCA) was conducted following ISO 14040 and ISO 14044 standards. It focused on representative commercial systems: PERC for the first generation, CdTe for the second generation, and tandem technologies for the third generation. System boundaries include raw material extraction, manufacturing, and module production. Six environmental impact categories are assessed, including global warming, resource scarcity, water consumption, land use, and ecotoxicity-related indicators.

The scientists also conducted sensitivity analysis to assess how degradation rate and service lifetime affect the environmental performance of PV panels and the competitiveness of tandem technologies. Degradation rates were used to reflect annual power losses, with higher values mainly associated with tandem PV due to perovskite stability issues. Service lifetime was varied between 15 and 35 years to capture differences between emerging tandem systems and mature silicon-based technologies. Energy payback time (EPBT) was also calculated to evaluate how long each PV technology takes to generate the energy required for its production.

The analysis showed that CdTe thin-film panels show the lowest environmental impacts overall, driven by their very low material and energy requirements compared to silicon-based and tandem systems. In contrast, first-generation silicon technologies such as Al-BSF, PERC, TOPCon, and heterojunction (HJT) exhibit higher impacts, although efficiency improvements significantly reduce emissions across successive designs. Tandem PV modules, meanwhile were found to offer lower impacts per kWh due to higher conversion efficiency, but their performance is highly sensitive to degradation rates and operational lifetime.

The research group also explained that key environmental hotspots include silicon wafer production, aluminium encapsulation, and energy-intensive manufacturing processes, while material scarcity impacts are strongly influenced by the use of aluminium, copper, and rare elements such as selenium and molybdenum, particularly in thin-film technologies.

The academics also found that recycling potential is highest for CdTe, while silicon-based systems face economic limitations despite large-scale deployment potential.

Sensitivity analysis also showed that high degradation rates can offset the environmental benefits of tandem technologies. “Our model considered the lead-based perovskites, which are the most studied on lab research due to the high efficiencies shown in laboratory tests,” Otero emphasized. “Firstly, the toxicity
aligned with the lead component appears as a relevant concern regarding the possibility of toxicity contamination. Researches have been developing other
perovskites substituting the lead component, such as tin; however, it has not yet surpassed the lead-based perovskites in terms of efficiency.”

“Other important points are related to the special challenges that tandem models impose on recycling, as the separation of both materials hinders the process and represents a new bottleneck for recycling,” she added.

The researchers also ascertained that a minimum operational lifetime of over 15 years is required for tandem systems to outperform conventional silicon panels environmentally, with EPBT results confirming CdTe as the fastest to recover embodied energy, followed by tandem systems and then silicon-based technologies.

These results suggest that tandem models could represent a significant advancement in solar PV technologies, enabling higher electricity output with lower environmental impacts,” the academics concluded. “However, the sensitivity analysis also indicated that technological improvements are required for tandem panels to achieve environmental performance comparable to first- and second-generation technologies, including further innovations to enhance perovskite stability and improve encapsulation techniques.”

Their findings are available in the study “Environmental performance of solar photovoltaics across three generations: A cradle-to-gate comparison,” published in Energy Conversion and Management.