For now, though, solar recyclers face significant economic, technical and regulatory challenges. Part of the problem, says NREL’s Curtis, is a lack of data on panel recycling rates, which hampers potential policy responses that could provide solar farm operators with more incentives to recycle end-of-life panels rather than throw them away.
Another problem is that the Toxicity Profile Leaching Procedure — an EPA-approved method for determining whether a product or material contains hazardous elements that could leach into the environment — is known to be flawed. As a result, some solar farm owners end up “overmanaging” their panels as hazardous without making a formal hazardous waste determination, Curtis said. They end up paying more to dispose of them in landfills that allow them to dispose of hazardous waste or recycle them.
The IEA assessed whether solar panels containing lead, cadmium and selenium could affect human health if dumped in hazardous waste or municipal landfills and determined the risk was low. Still, the agency said in a 2020 report that its findings did not constitute an endorsement of landfills: Recycling would “further alleviate” environmental concerns, it said.
NREL is currently investigating an alternative process for determining whether a panel is hazardous. “We need to figure this out because it definitely impacts liability and cost, making recycling more competitive,” Curtis said.
Despite these uncertainties, four states have recently enacted laws addressing PV module recycling. California, which has the most solar installations, allows the panels to be dumped in landfills, but only if they are certified harmless by a designated lab, which can cost upwards of $1,500. As of July 2022, only one recycling plant in California will accept solar panels.
In Washington state, a law aimed at providing an environmentally friendly way to recycle photovoltaic panels is due to go into effect in July 2025; New Jersey officials are expected to release a report on managing photovoltaic waste this spring, and North Carolina has directed state Environmental officials study decommissioning of utility-scale solar projects. (North Carolina currently requires solar panels to be disposed of as hazardous waste if they contain heavy metals such as silver or, in the case of old panels, hexavalent chromium, lead, cadmium and arsenic.)
In the European Union, since 2012, end-of-life photovoltaic panels are considered electronic waste under the European Union’s Waste Electrical and Electronic Equipment Directive (known as WEEE). The directive requires all member states to adhere to minimum standards, but actual e-waste recycling rates vary by country, said Marius Mordal Bakke, senior analyst for solar supplier research at Oslo, Norway-based research firm Rystad Energy. Despite the law, PV recycling rates in the EU are no better than in the US — about 10 percent — largely because of the difficulty of extracting valuable materials from panels, Bakke said.
But he predicts recycling will become more common when the volume of scrapped panels increases to the point where it presents a business opportunity, providing recyclers with valuable material they can sell. He added that the government could help speed up the transition by banning the disposal of photovoltaic panels in landfill and offering incentives such as tax breaks to anyone who uses solar panels.
“At some point in the future, you’re going to see enough panels being retired that you have to start recycling,” Bakke said. “It’s going to be self-profitable regardless of commodity prices.”