Researchers Develop Acid-Free Technology to Recover 97 Percent Silver from End-of-Life Solar Panels

Researchers at the University of Newcastle have developed a fast, safe and acid-free method to recover over 97 per cent of silver from end-of-life solar panels, marking a major breakthrough in solar waste recycling and critical minerals recovery.

The new technique retrieves high-grade silver from discarded photovoltaic (PV) panels in just a few minutes, using a physical separation process rather than chemical-intensive methods that typically take hours and pose environmental and safety risks.

The research was led by Associate Professor Mahshid Firouzi from the University’s Centre for Critical Minerals and Urban Mining (CRITIUM).

“Solar panels and the valuable minerals they contain do not need to end their life as waste,” Associate Professor Firouzi said. “By using flotation, a fast and well-established mineral beneficiation technique — we can recover almost all of the silver in an end-of-life solar panel without using any acid,"  said Firouzi.

The method combines comminution, where panels are mechanically crushed into fine particles, with froth flotation, a separation process that uses water, air bubbles and small amounts of standard flotation reagents. Valuable metals float to the surface while waste materials sink.

While froth flotation is widely used in mining, this is believed to be the first successful demonstration of its use for recovering metallic silver from recycled solar panels.

“Many in the field believed this wasn’t feasible,”  she added. “Our results prove otherwise, noted Firouzi.

End-of-life PV panels contain 300–500 parts per million (ppm) of silver, comparable to, and in some cases exceeding, the cut-off grade of primary silver mines.

Australia, which has the highest solar capacity per capita globally, is expected to generate over one million tonnes of solar panel waste by 2050, containing an estimated 300–500 tonnes of silver.

The 18-month study involved collaboration between two University of Newcastle research centres based at the Newcastle Institute for Energy and Resources (NIER). The team included PhD candidate Hamidreza Saffarian and Laureate Professor Kevin Galvin, Director of both research centres.

End-of-life PV samples were supplied by industry partner Circular Solar Solutions, with additional support from KGM Services Pty Ltd / The Solar Professionals under a Cooperative Research Centres Projects grant.

Jeremy Grant of The Solar Professionals said  that the results exceeded expectations, as he pointed out, “We’re excited about the opportunity to further refine and apply these techniques to advance metal recovery from end-of-life PVs. This is exactly the kind of innovation the sector needs.”

The research team is now investigating silicon recovery, which makes up nearly 90 per cent of the weight of crystalline solar cells and is critical to global solar manufacturing.

“Silver is just the beginning,” Firouzi said. “There are billions of dollars’ worth of valuable metals locked inside urban and industrial waste. We simply cannot afford to let them go to landfill," she added.

The project ultimately aims to commercialise sustainable end-of-life solutions for solar panels, supporting a circular economy, reducing environmental impact, and creating new jobs in resource recovery and advanced manufacturing.