The transition to renewable energies in an effort to mitigate the effects of climate change will mean plenty more investment in solar power from California to Rajasthan. There’s a bit of a problem, though: nothing lasts forever and that includes solar panels. Disposing of old and outdated solar panels after they have been replaced with new ones can be a challenge.
The German engineering firm Geltz Umwelt-Technologie has a solution, however. In an EU-funded project, the company has constructed a waste treatment facility at a large disposal firm with the aim of retrieving reusable materials from solar modules so that they do not end up in landfills. For now the pilot project remains a work in progress, but it can already tackle the recycling of the modules’ aluminum frames and cover glasses.
“Solar module layers are bonded together with polymers that make mechanical separation and treatment of solar module components almost impossible,” an employee of the company, Fabian Geltz, notes. “Up until now, there has not been any technical solution to recycle and separate the valuable materials from the mixed scrap. The critical step in the recycling process is therefore the destruction of the polymer layers.”
Solar panels regularly contain lead, cadmium, and other toxic chemicals that can only be removed by taking apart the panels. “Approximately 90% of most PV modules are made up of glass,” explains Dustin Mulvaney, an associate professor of Environmental Studies at San Jose State University in the US. “However, this glass often cannot be recycled as float glass due to impurities. Common problematic impurities in glass include plastics, lead, cadmium and antimony.”
The new process relies on energy-efficient pyrolysis whereby undesired polymer layers are dissolved so that the glass in panels can be retrieved. During the process components made from aluminum, glass, silver, copper, tin and silicon can then be isolated and separated. “Thanks to the successful recovery of materials and components, the unusable solar module can become a valuable source of raw materials for the future,” Geltz says.
Once the project becomes fully operational, it could process as many as 50,000 solar modules a year. One cycle of the pyrolysis process should treat 1 metric ton of solar module waste while the project’s recovery methods should yield over 95% of recycled material.
This project could be a huge step forward for waste disposal in the field of solar power, which is bound to produce vast amounts of waste in coming decades. According to the International Renewable Energy Agency, in 2016 alone there was some 250,000 metric tons of solar panel waste produced worldwide. By 2050, that sum could reach 78 million metric tons.