Energies Media
The bogs of southeastern Massachusetts have produced cranberries for more than two centuries, and the Weweantic River still threads between them the way it always has.
In recent years something new has appeared above the waterlogged soil: row after row of ground-mounted solar panels, their dark faces tilted toward the sky.
They look clean.
They are sold as clean.
But on the underside of each panel, facing the ground and the water below, sits a thin plastic layer most buyers never see and most installers never mention.
Scientists just spent the better part of a year trying to understand what that layer is made of, and their answer turned out to be more complicated than anyone expected.
Flip a solar panel over and you will find its backsheet, a laminated layer meant to protect the electronics from rain, heat and decades of weather.
Durability is the whole point.
To get it, some manufacturers reach for a family of synthetic chemicals called fluoropolymers, a cousin of the larger class of compounds the public knows as PFAS, or forever chemicals.
PFAS get their name from an almost unbreakable carbon fluorine bond.
They are a broad class of thousands of synthetic compounds, highly persistent in the environment and resistant to natural degradation.
That bond is exactly what makes them useful in a backsheet meant to survive thirty years of rain.
It is also exactly what makes them troubling if they ever reach the water table below a bog.
The solar industry does not make it easy to find out what a backsheet contains.
When researchers polled manufacturers and academic experts, the answers were fragmentary at best.
Fifty-four percent of survey respondents selected the backsheet as a component of concern, and 39 percent chose the solar glass coatings.
One researcher noted that “while many experts suspect PFAS involvement, there is no clear, shared understanding or publicly accessible knowledge base.”
That opacity has real consequences in places like Carver and Wareham, Massachusetts, where solar arrays now sit alongside the Weweantic and its bordering wetlands.
Rain falls on panels.
Runoff moves downhill toward shallow groundwater.
The distance between a backsheet and a cranberry bog is sometimes measured in feet, not miles.
State regulators and local conservation boards have begun asking exactly what chemicals those panels carry.
The answer from industry is not reassuring, not because the answer is bad, but because in many cases no answer exists.
The proprietary nature of some fluoropolymer manufacturing processes means it is not clear whether PFAS are involved at all.
Community groups near the Weweantic have pointed out that getting that answer wrong after hundreds of acres are already installed could be severe.
The United States Environmental Protection Agency plans to propose new rules in 2025 to add solar panels to the universal waste regulations, with a proposed final rule at the end of 2026.
The bogs are not waiting for a final rule.
The clearest look yet at the question came in April 2026, when researchers from Michigan State University and Oak Ridge National Laboratory published a perspective in MRS Energy and Sustainability.
They found that while fluoropolymers may be used in limited components like backsheets or coatings, there is no confirmed evidence of PFAS leaching from commercially deployed solar modules.
The study also highlights widespread confusion between different PFAS types and emphasizes the need for transparency around fluoropolymer use in solar technology.
But the researchers were careful about what they were not saying.
The industry is already moving toward bifacial modules with glass on both sides, eliminating the need for backsheets altogether.
Older installed panels are not moving anywhere, and the community solar projects multiplying across the northeastern United States often use conventional module designs that still carry backsheets.
The Weweantic River does not need a final answer about chemistry to keep flowing.
But the cranberry farmers and conservation commissions who watch over its banks do need one thing the April 2026 study identified as still missing: transparency.
The work highlights that fluoropolymers are often not appropriately differentiated from more hazardous PFAS, and that mischaracterizing them may lead to misleading conclusions about the environmental sustainability of solar technology.
Industry experts say most newer solar panels are being made with PFAS substitutes, though that shift has not yet reached batteries, electrolyzers or inverters.
Canal top and wetland adjacent installations are among the sites where that shift matters most.
The bog will keep producing cranberries.
The panels will keep producing power.
And the thin plastic layer between them and the water below is finally, for the first time, something scientists are watching closely.
Hugo is an engineer with strong technical expertise and deep knowledge of the space industry. Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.
Hugo is an engineer with strong technical expertise and deep knowledge of the space industry. Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.
Hugo is an engineer with strong technical expertise and deep knowledge of the space industry. Multilingual from an early age, his writing combines technical clarity with a strong interest in science and energy.

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