University of Newcastle researchers have taken a significant step toward making solar panel recycling profitable, successfully scaling up a process that recovers nearly all of the silver locked inside end-of-life panels.
The team ran the world’s first continuous pilot-scale flotation trial for solar panel recycling, processing 22 kilograms of solar-cell material recovered from about 460 kilograms of retired panels, roughly the equivalent of 23 residential solar panels.
The trial achieved close to 100 per cent silver recovery, concentrating the metal into a high-value product that made up just 1.25 per cent of the original material but contained more than 80 times the silver concentration of the untreated solar-cell material.
The process builds on earlier research from the university’s Centre for Critical Minerals and Urban Mining, known as CRITIUM, which showed that froth flotation, a mineral-processing method long used in mining, could extract silver from solar waste without acid.
Associate Professor Mahshid Firouzi, Deputy Director of CRITIUM, said the latest results show the technique can work continuously at a much larger scale.
Instead of the large volumes of acid used in conventional recovery methods, the university’s approach relies on water, air and small amounts of chemicals that cause silver particles to attach to air bubbles, allowing them to be separated out and collected.
According to the research team’s preliminary economic modelling, the flotation-based method could end up three to five times cheaper than conventional acid-leaching processes, which become costly at scale because of their chemical use and the hazardous waste they generate.
That matters because recycling a solar panel currently costs about $10 to $15, compared with just a few dollars to send it to landfill, a gap that has made recycling a hard sell despite the growing waste problem.
“Silver is the highest-value material in a solar cell. Recovering it has the potential to make solar-panel recycling far more financially attractive,” said Associate Professor Firouzi.
The scale of the challenge is considerable. Australia is projected to generate more than one million tonnes of waste solar panels by 2050, a stream expected to contain between 300 and 500 tonnes of silver.
While glass and aluminium from old panels are already routinely recovered, the silver embedded in solar cells has largely been left to end up in landfill.
Associate Professor Firouzi said recovering critical minerals from renewable energy waste will only grow in importance as Australia’s transition continues, and that building a genuine circular economy means thinking beyond generating clean energy to also recovering the materials that make the technology possible.
The research team, based at the university’s Newcastle Institute for Energy and Resources, includes PhD candidate Hamidreza Saffarian from the ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, along with Centre Director Laureate Professor Kevin Galvin.
The group is now exploring whether the same flotation technology could be applied to other waste streams, including printed circuit boards from decommissioned data centre equipment and broader categories of electronic waste.
The findings have been released as a preprint on ChemRxiv, ahead of formal peer review.