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U.S. researchers at the Department of Energys National Renewable Energy Laboratory used a circular economy framework to determine how to scale, deploy and design perovskite metal halide solar panels so that they are easily recyclable in the future.
Researchers at the U.S. Department of Energys National Renewable Energy Laboratory (NREL) used a circular economy framework to determine how to scale, deploy, and design future metal halide perovskite solar panels to be easily recyclable.
As efforts to commercialize metal halide perovskite (MHP) solar technology are underway, especially efforts to ensure long-lasting performance in the field, NREL researchers initiated a study of sustainability design factors as another important aspect of commercialization.
“Our goal with this perspective paper was to point out that existing technology does not prioritize building products with sustainability and circularity up front. It was not specifically developed to minimize waste or utilize the lowest energy processing steps,” Joey Luther, corresponding author of the research, told pv magazine . “However, since PV is inherently a sustainable technology, now is the time to start evaluating how we can develop the commercialization of MHPs with sustainability in mind.”
The group performed the evaluation based on a prototypical single-junction MHP module close to commercial designs, framed with mounting rails in a glass module configuration with polymeric encapsulants and edge sealing typical of silicon and cadmium telluride panels. Individual PV cells are integrated by scribing and include front glass coated with a transparent conductor, the MHP layer sandwiched between electron and hole transport materials, and a back electrode.
In addition, the team delved deeper into the chemical components, molecules and materials typically used in the A, B and X sites of perovskite.
For all of them, sustainability aspects were evaluated, such as energy intensity of manufacturing, carbon intensity, extraction of rare minerals, recyclability, land abundance, cost, fossil fuel derivatives, fail-safe encapsulation, health risks and flammability, among others.
The prototype was further evaluated for critical materials, embodied energy, carbon footprint, and circular supply chain processes. The analysis included the frame, rail materials, front and back glass, encapsulation polymers, solvents, electron and hole transport materials, and electrode materials.
In a table packed with information, the team detailed how the eleven “Rs” of circularity for photovoltaics can offer opportunities and advantages within sustainable manufacturing. It is an adaptation of the concept “reduce, reuse, recycle”, and some of the “Rs” that are analyzed are the following: reject fossil fuels and carbon-intensive materials; reduce energy, materials and carbon consumption; repair or design to repair, reuse, repower, restore and recover energy.
As for recycling, the researchers noted that “recycling” includes both “downcycling” and “recycling” into lower value or quality products. They explained that recycling is beneficial when recovered raw materials replace virgin materials, which require energy-intensive refining. There is room for improvement. For example, they noted that photovoltaic glass manufacturing continues to use virgin sources in new photovoltaic glass products and not post-consumer photovoltaic glass chips.
The team identified five key areas and opportunities. The first is to improve the reliability of MHP modules to meet current commercial PV lifetime standards. Second, investigate the supply chain for low-volume commodity feedstocks such as cesium and ensure adequate accessibility for sustainable scaling up of a given MHP composition, or focus research on its reduction or substitution. Third, look for alternatives to indium. Fourth, explore how to accelerate recycling of PV glass without reducing it. And fifth, continue to improve module remanufacturing processes.
“A reasonable combination of these solutions would enable MHP-PV to make a significant and sustainable contribution to the energy transition,” the team stresses.
The scientists stated that “circularisation of the PV supply chain, particularly through glass recycling and remanufacturing,” offers opportunities to reduce the embodied energy and carbon of MHP-PVs. “Improvements in lifetime and reliability remain paramount to the energy transition and provide the greatest benefits,” they concluded.
The outlook is detailed in “ Sustainability pathways for perovskite photovoltaics,” published by Nature Materials . |
