Using laser ablation to extract silver from old solar panels

The growth of the photovoltaic sector has stood out among renewable energy sources thanks to technological innovations that have reduced costs. The average panel of about 2 square meters can use up to 20 grams of silver, which is the most efficient and cost-effective electrical and thermal conductor in the world.

A research project at the University of Virginia aims to prove there’s a better way to extract silver from old solar panels to put the valuable material back into new solar panels, biomedical devices and other uses. productive.

The majority of photovoltaic solar cell manufacturing uses thick-film screen printing metallization with a silver-containing paste to produce solar cells. The pastes mainly used include rear silver, rear aluminum and front silver. Manufacturers then use the screen printing process and high temperatures to achieve the thin silver lines visible on the outside of the panels’ photovoltaic cells.

For silver recovery, the researchers will use a new method called laser ablation on PV cells, converting the silver electrical contact material into nanoparticles. After extraction, the silver will no longer need to be refined before it can be used in new silicon modules. The recovered silver could also be purified for other uses.

UVA engineering professor Mool Gupta is the principal investigator for the project, which received a one-year, $250,000 grant from the Department of Energy in June. The project is part of a $6 million overall effort by the DOE’s Office of Solar Energy Technologies to initiate small, innovative projects in photovoltaic and solar thermal technologies.

The patent-pending technology will be a greener approach to the existing silver mining method, which uses nitric acid to recover silver from old or broken silicon solar cells – the technique which can be harmful environmentally and inefficient. According to Professor Gupta, if their process can be perfected, solar panel manufacturers and recycling companies would have an incentive to take back old panels and get more out of them, to the benefit of consumers and the environment.

Solar panels have a useful life of up to 25 years. Manufacturers don’t tend to refurbish panels after that because of the cost. The main avenue for the reuse of old panels has therefore been through glass recycling facilities, where the glass and sometimes the frames are recovered before the other elements are burned or otherwise disposed of. By 2050, solar module waste is expected to reach 78 million tonnes.

“It’s hard to compete with the low-cost, environmentally-unfriendly landfill approach,” Gupta said. But he and his team are convinced that the new technology can.

“Professor Gupta’s advances in research and innovative use of laser ablation represent a key step in realizing clean, sustainable and inexpensive energy sources for the future,” Professor Scott Acton, chair of the Department of Electrical and Computer Engineering, said.

meta: Researchers are using laser ablation to extract silver from old solar panels to put the valuable material back into new solar panels and biomedical devices.