Researchers at the National Renewable Energy Laboratory (NREL) in the US have conducted the first global assessment for solar panel recycling.
Photovoltaic (PV) modules in solar panels have a 30-year lifespan but there is currently no plan for how to manage this at end of their lifespan. The volume of modules no longer needed could total 80 million metric tons by 2050. The nature of the waste also poses challenges. PV modules are made of valuable, precious, critical, and toxic materials. There is currently no standard for how to recycle the valuable ones and mitigate the toxic ones.
“PV is a major part of the energy transition,” said Garvin Heath, a senior scientist at NREL who specializes in sustainability science. “We must be good stewards of these materials and develop a circular economy for PV modules.”
The paper on “Research and development priorities for silicon photovoltaic module recycling supporting a circular economy” appears in the journal Nature Energy.
“It provides a succinct, in-depth synthesis of where we should and should not steer our focus as researchers, investors, and policymakers,” said Heath.
The report looks at the recycling of crystalline silicon, which is used in more than 90 percent of installed PV systems today. It accounts for about half of the energy, carbon footprint, and cost to produce PV modules, but only a small portion of their mass.
“It takes a lot of investment to make silicon pure,” said Timothy Silverman, a PV solar panel hardware expert at NREL. “For a PV module, you take these silicon cells, seal them up in a weatherproof package where they’re touching other materials, and wait 20 to 30 years—all the while, PV technology is improving. How can we get back that energy and material investment in the best way for the environment?”
Some countries have PV recycling regulations in place, while others are just beginning to consider solutions. Currently, there is only one crystalline silicon PV-dedicated recycling facility in the world due to the limited amount of waste being produced today.
The FRELP project (Full Recovery End of Life Photovoltaic) was part of the European “LIFE” programme to develop techniques to recover waste crystalline-silicon PV solar panels, recovering glass, aluminium, silicon, copper and silver, recovering 908 kg out of each 1000 kg load. This was handled by PC Cycle in Italy in 2016.
Based on their findings, the authors recommend research and development to reduce recycling costs and environmental impacts, while maximizing material recovery. They suggest focusing on high-value silicon versus intact silicon wafers. This will need research and development into silicon purification processes.
“We need research and development because the accumulation of waste will sneak up on us,” said Silverman. “Much like the exponential growth of PV installations, it will seem to move slowly and then rapidly accelerate. By the time there’s enough waste to open a PV-dedicated facility, we need to have already studied the proper process.”
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