Study finds tandem PV has 30% lower environmental impact than crystalline silicon

A Spanish research team has found that perovskite-silicon tandem photovoltaic systems can reduce environmental impacts by approximately 30% compared to traditional silicon-based PV panels, according to their recent study. This development could influence future PV technology choices, provided challenges related to stability and lifetime are addressed.

The study, conducted by a group from Universitat Politècnica de Catalunya, assessed eight PV technologies across three generations, focusing on cradle-to-gate life cycle impacts. It found that tandem PV modules, which combine perovskite and silicon layers, demonstrate improved environmental performance mainly due to higher efficiencies, with lab-scale conversion efficiencies over 30%. However, these systems currently require long operational lifetimes—more than 15 years—to outperform traditional silicon panels environmentally.

While tandem PV systems show lower impacts per kilowatt-hour due to their higher efficiency, their performance is highly sensitive to degradation rates and stability issues. The research also indicates that thin-film technologies, such as cadmium telluride (CdTe), still have the lowest overall environmental impacts, driven by their minimal material and energy requirements. The study highlights that recycling processes for tandem panels are more complex, with material separation posing a challenge, and that current lead-based perovskites raise toxicity concerns.

Implications for Future Solar PV Development

This research underscores the potential of tandem PV technologies to reduce environmental impacts of solar energy, supporting efforts to make solar power more sustainable. However, the need for enhanced stability, longer lifespans, and improved recycling methods indicates that tandem systems are not yet ready for widespread deployment. The findings may influence research priorities and policy decisions aimed at advancing high-efficiency, low-impact solar solutions.

Background on PV Technologies and Environmental Assessments

The assessment builds on previous evaluations of PV technologies, including first-generation silicon-based modules like PERC, second-generation thin films such as CdTe, and emerging third-generation tandem systems. The study follows ISO standards for life cycle analysis, considering raw materials, manufacturing, and module production impacts. Prior research has shown that thin-film technologies like CdTe have the lowest environmental footprints, but tandem systems are gaining attention for their higher efficiencies. The study’s focus on cradle-to-gate impacts provides a comprehensive view of environmental hotspots, including silicon wafer production and material scarcity issues.

“Perovskite-silicon tandem technologies have shown a reduced environmental impact compared to current dominant silicon-based cells.”

— Julia Otero

Uncertainties Surrounding Tandem PV Stability and Recycling

It is not yet clear how long tandem PV systems can reliably operate at high efficiency, as current stability issues related to perovskite materials may limit lifespan. The environmental benefits are highly sensitive to degradation rates, and recycling processes for tandem modules are still under development, posing potential bottlenecks for large-scale deployment.

Next Steps for Tandem PV Research and Deployment

Further research is needed to improve the stability and lifespan of tandem PV modules, particularly addressing perovskite stability and encapsulation techniques. Advances in recycling methods are also crucial to maximize environmental benefits. Monitoring real-world operational data will help validate laboratory findings and inform industry standards. Policy and investment decisions may shift to support these improvements, potentially accelerating commercial adoption of tandem PV technology.

Key Questions

How much lower is the environmental impact of tandem PV compared to silicon?

The study estimates that tandem PV systems can have approximately 30% lower environmental impacts than traditional silicon-based panels, mainly due to higher efficiency and lower material use in thin-film layers.

What are the main challenges for tandem PV to become more sustainable?

The primary challenges include improving the stability and operational lifetime of perovskite layers, addressing toxicity concerns related to lead-based perovskites, and developing effective recycling processes for tandem modules.

Are tandem PV systems currently commercially available?

While laboratory efficiencies exceed 30%, commercial production of stable, long-lasting tandem PV modules is still under development. Most current systems are in research or pilot phases.

How does the environmental impact of tandem PV compare to thin-film technologies like CdTe?

According to the study, CdTe thin-film panels currently have the lowest overall environmental impacts, driven by minimal material and energy requirements, but tandem PV offers higher efficiencies which could translate into lower impacts per unit of energy produced if stability issues are resolved.

Source: PV Magazine