Researchers at the Fraunhofer Institute for Solar Energy Systems in Germany have developed a process that uses 100% recycled silicon from solar photovoltaic models to produce new PERC solar cells.
More than a million tonnes of solar panels end up in landfill
The average service life of a solar panel is between 15 to 25 years. Researchers from Deakin’s Institute for Frontier Materials advise that, without a silicon recycling process, by 2050 there will be around one point five million tonnes of solar panel waste in landfill – the equivalent of around 100,000 small cars.
Already, the aluminium, glass, and copper from these discarded solar PV modules are recovered, but the same has not been true for silicon.
The solar panel recycling process
The Fraunhofer ISE silicon recycling process sees solar cell fragments separated from by-products of the mechanical recycling process – a process which already exists in manufacturing – and frees the silicon cell fragments from the glass and plastic.
Silicon cleaned in this way is processed into monocrystalline or quasi-monocrystalline ingots in standard processes and then into wafers. The crystallisation is carried out with 100% recycled silicon without adding commercial ultrapure silicon. Wafers of recycled silicon were fabricated into passivated emitter and rear contact (perc) cells. In the first trial, the conversion efficiency was 19.7%.
“This is below the efficiency of today’s premium perc cells, which have an efficiency of around 22.2% but it is certainly above that of the cells in old, discarded modules,” says Professor Peter Dold, project manager at Fraunhofer. “It was important for us to develop a scalable process that makes economic sense. A lot is possible in the lab but our new process should prove itself in the practice for the recycling industry.”