Researchers led by the University of Glasgow in Scotland have developed a laser-induced delamination method for recycling aged crystalline silicon solar modules. The process separates the ethylene-vinyl acetate (EVA) encapsulant from the silicon cells, producing cleaner material streams for the subsequent selective recovery of silver and aluminum.
“End-of-life crystalline-silicon photovoltaic modules remain difficult to recycle because EVA adheres strongly to cell interfaces, and dominant routes rely on shredding or bulk thermal treatment, generating mixed fractions,” the researchers said. “This study demonstrates that laser-induced delamination provides a selective, dry pathway for removing EVA from aged c-Si PV laminates by targeting the EVA–Si interface, thus reducing the intermixing of materials.”
The researchers combined hot-knife glass removal with laser-induced delamination to separate aged PV laminates into three material streams: largely intact EVA films containing trace metal residues, isolated busbars, and silicon-rich cell powder. They tested two types of modules aged approximately 10 to 13 years, using a 1,064 nm fiber laser to target the EVA-silicon interface.
The experiments involved laser powers ranging from 9 W to 27 W at pulse frequencies of 30 kHz, 40 kHz, and 50 kHz on 20 mm × 20 mm samples, with additional tests conducted on larger specimens.
The researchers subjected the resulting powder to sequential leaching with 1 M sodium hydroxide to remove aluminum, followed by an iron(III) chloride-choline chloride brine to extract silver, leaving crystalline silicon. They compared the extraction results with a nitric acid benchmark and assessed the separation process using sample weighing, microscopy, spectroscopy, thermal analysis, and X-ray diffraction.
The tests showed that EVA separation began at approximately 12 W to 14 W, with nearly complete separation achieved at around 18 W to 20 W and higher. The process produced largely intact EVA films, isolated busbars, and silicon-rich powder with negligible polymer contamination.
Sequential leaching achieved silver extraction selectivity of more than 95% for both module types, exceeding 99% in one case. Extracted silver accounted for 1.08% to 1.38% of the powder mass, while aluminum removal ranged from 7.79% to 8.54%.
X-ray diffraction confirmed that crystalline silicon remained after treatment, while diffraction peaks associated with silver and aluminum disappeared. Small amounts of metal residues remained in the EVA, particularly around busbar contact regions, suggesting potential for further recovery.
“To the best of our knowledge, this is the most selective silver extraction reported for aged panels,” the researchers concluded. “Because the laser targets only the EVA–silicon interface, not the bulk laminate, the hot-knife plus laser route should need less energy than pyrolysis or thermo-solvent treatment, lowering process intensity while improving chemical tractability for selective metals recovery.”
The researchers presented their findings in “Laser-induced delamination of aged silicon photovoltaic modules to achieve >95% selective silver recovery,” which was recently published in Communications Materials. The research team included scientists from Saudi Arabia’s Princess Nourah bint Abdulrahman University and Germany’s Fraunhofer Center for Silicon Photovoltaics (CSP).
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