Italian researchers say removing PV module backsheets before thermal recycling keeps titanium dioxide out of recovered materials and cuts particulate emissions by over one-third, but raises propane use by about 20%.
Researchers in Italy have found that removing the backsheet from crystalline silicon PV modules before thermal recycling produces cleaner recovered materials and lowers particulate emissions, without reducing recovery yields.
The team tested a selective backsheet-removal step, patented by Italy’s National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) and Beta-Tech, upstream of the pilot-scale thermomechanical recycling process developed by Venice-based startup 9-Tech.
The scientists compared modules processed with and without their backsheets on material recovery, energy demand, the composition of recovered fractions and flue-gas emissions.
They said that removing the backsheet did not adversely affect recovery yields for the main materials. It also kept titanium dioxide, a white pigment used in PET-based backsheets, out of the recovered glass, silicon-rich, metallic and fine fractions. The researchers noted that titanium dioxide transferred into recycled fractions can reduce their quality, particularly in silicon recovery.
Particulate emissions fell from 69.0 mg/Nm³ to 44.1 mg/Nm³. The process also allows the polymer backsheet to be recovered separately rather than burned.
Energy penalty
The scientists said that the trade-off was a roughly 20% increase in external propane demand, because the feed contained less combustible polymer once the backsheet was removed. Electricity consumption was unchanged.
The tested modules, Trina Solar TSM-230PC05 panels, had a non-fluorinated PET-based backsheet, so hydrogen fluoride stayed below detection limits in both configurations. The researchers said removing fluorinated backsheets before thermal treatment would be expected to prevent their contribution to hydrogen fluoride formation, but they did not test this.
The researchers said that 9-Tech’s process thermally removes organic components and then mechanically separates glass, copper ribbons and silicon-rich fractions. The pilot plant, in Porto Marghera near Venice, has a capacity of 30 kg per hour. The work was carried out under the Horizon Europe EVERPV project, which is developing delamination technologies for end-of-life panels. Two of the authors have financial ties to 9-Tech, and a third holds the backsheet-removal patent.
The scientists described their findings in “Early backsheet removal as a strategy to optimize photovoltaic panel recycling by thermal treatment,” which was recently published in Waste Management.
In 2024, 9-Tech said that its pilot line had recovered 87% of the material in the end-of-life modules it processed. The company is also developing an industrial-scale plant in Porto Marghera with local utility Veritas.
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