Recycling of solar panels? Not yet. A new technology from Brno University of Technology offers a solution
Silver, silicon, tin, and zinc—wafers from decommissioned solar panels contain a range of metals that would be useful to separate or reuse in new alloys. Until now, however, no technology has existed that would allow for their ecological and economically viable recycling. Researchers from the Materials Research Centre at the Faculty of Chemistry, Brno University of Technology, have now come up with a solution.
Pressed tablet containing aluminum shavings and a silicon wafer from photovoltaic panels | Author: Václav Koníček
The number of solar panels in recycling company storage is growing—according to data from VIA ALTA, 3–4 tons must currently be disposed of *daily* in the Czech Republic. This number is expected to grow significantly, as the solar panel boom began in 2010, and their lifespan, depending on the technology, ranges from 10 to 25 years.
This issue is not limited to the Czech Republic; other European countries face it too. Chemists at the CMV (Materials Research Centre) at BUT were therefore tasked by VIA ALTA experts with a difficult challenge: to develop a functional model of a technology that would enable the ecological and economically viable processing of tons of waste.
Jaromír Wasserbauer and Matěj Březina from the Laboratory of Metals and Corrosion | Author: Václav Koníček
“Manufacturers usually claim that their solar panels are fully recyclable. But that’s not true. About 90% of the panels are recycled, which meets legal requirements—they remove the massive glass and the aluminum frame that holds the structure together. But a smaller conductive part remains, called the wafer, which is sealed in polymer. It contains silver and other interesting metals,” explains project lead Jaromír Wasserbauer from the Laboratory of Metals and Corrosion at CMV.
During the three-year project, researchers had to abandon their original plan to separate individual metals. “Burning the material is an environmental disaster due to the fluorinated polymers used. So we tested a chemical process that's ideal for extracting metals from mobile phones containing gold,” explains Matěj Březina, head of the research section.
They placed the polymer from the solar panel into a solvent and successfully extracted individual metals. However, the process was not only slow but also expensive. “Silver is many times cheaper than gold, and solar panels contain only a trace of it, so the recycling technology wouldn’t pay for itself,” Březina notes, listing the dead ends they encountered during the project.
Ultimately, the researchers opted for the opposite strategy—instead of separating the metals, they added aluminum machining shavings to the crushed wafer.
They pressed the two types of waste from different sources into aluminum pucks that can be used in foundry production. “We realized that all the metals contained in the wafers can be used to improve the properties of aluminum alloys. Foundries can melt the pucks in the right ratio with aluminum and start producing,” concludes Wasserbauer. Thus, a piece of a discarded solar panel can be transformed into a new engine or gearbox block.
Currently, CMV researchers want to focus on recycling technologies for other types of solar panels. Newer solar panels may no longer contain silver but include a wide range of other interesting elements—such as copper, indium, gallium, selenium, sulfur, zinc, or cadmium.
The research project was supported by the Technology Agency of the Czech Republic under the TREND 1 program.
