In the United States, solar is the fastest growing source of energy, with an estimated 49% increase in capacity by 2027 from 2025. According to a report published in March 2026 by the Solar Energy Industries Association, in 2025 solar installations accounted for 54% of all new electricity-generating capacity added to the U.S. grid. 

As more and more solar panels are coming online, another question is being raised: What happens when they are retired? Solar panels have a lifetime of about 20 to 30 years, after which a majority end up in landfills. With large-scale solar panel installations set to increase and early solar installations reaching retirement, the question of what to do with these solar panels is becoming hard to ignore. 

One group of master’s students at the University of Michigan School for Environment and Sustainability (SEAS) advised by Geoff Lewis, research area specialist lead and adjunct lecturer, worked with the National Renewable Energy Laboratory to address this question. Megan DiFranco (MS ’26), Kade Phoonsiri (MS ’26), Edgar Venegas (MS ’26) and Jianshen Yu (MS ’26) researched the policy, industry and community conditions needed for a circular economy for solar panels in the United States as part of their project, “Enabling a Circular Economy for Solar Photovoltaics and Battery Energy Storage.”

“There’s very little information out there on solar panel decommissioning,” said DiFranco. “We wanted to contribute to that conversation.”

Solar panel decommissioning refers to how solar panels are retired once they have reached the end of their usable lifetime. In a circular economy, solar panels and their materials would be recovered and recycled. “It decreases our dependency on virgin materials to create clean energy solutions,” said Venegas.

The team divided their research so that each member utilized their strengths and interests. DiFranco led efforts to look at state-level policies on solar panel decommissioning. Surveying policies across all 50 states, she has found that since 2017, there has been an uptick in solar panel decommissioning policies. However, a majority of these policies focus on requiring studies that will make recommendations towards decommissioning. A few states have gone further, such as California, allowing solar panels to be treated as universal waste, reducing the regulatory burden on disposal. For the team, these states could be a blueprint for solar decommissioning policies. 

Venegas investigated circular economies in other industries already functioning at scale to learn what can be replicated. He found that the lead-acid battery industry has a 99.9% recycling rate through a national take-back program. “As more networks are connected, the circularity of these panels becomes feasible,” Venegas said.

Yu focused on the chemistry and potential toxicity of solar panels. Solar panels contain several potentially hazardous elements, and regulations focus on leaching as the primary environmental risk. The problem, he explains, is that “it’s hard for solar panels to leach anything out” under normal circumstances, making the testing method a poor fit for the material. Yu argues there should be alternative screening methods to accurately characterize risk.

Phoonsiri led the team on researching how communities understand and respond to solar developments. She found that since 2021, fear of toxic chemicals has driven increasing opposition towards solar panels. The team hopes their research can debunk the fear of toxins. “People still refuse to believe it’s hard for solar panels to leach [contaminants],” she says. The policy implications are real: As DiFranco noted, decommissioning regulations do little if communities block projects from being built in the first place.

The team hopes their findings, which will be combined into a publicly available final report, will be used to help guide future decisions and policies on solar panels to support a circular economy. Project advisor Lewis adds that “this team has provided a great example of the application of life cycle assessment and material circularity concepts to guide real-world policy creation and decision-making.” By bridging knowledge gaps, the team believes their research can help ensure that the future of solar energy is shaped not just by policy and industry, but by the communities that host it.