Are Solar Panels Toxic? What's in Them — and What Happens When They Wear Out

At county hearings from Ohio to Alabama, the claim arrives on schedule: solar panels are full of toxic chemicals that will leach into the groundwater and poison the wells. It is one of the most repeated arguments against utility-scale solar — and one of the most answerable. A solar panel is, by weight, overwhelmingly glass and aluminum wrapped around a wafer of silicon, the second most abundant element in the Earth's crust. The toxicity question is really about trace materials measured in fractions of a percent — and there is real testing data on exactly what those traces do.

The Quick Answer

• About 95% of solar panels installed worldwide are crystalline silicon: glass, aluminum frame, silicon cells, copper wiring, a small amount of silver, and less than 0.1% lead in the solder, sealed inside laminated glass. No cadmium.
• The remaining ~5% are cadmium telluride thin-film panels, which do contain a cadmium compound — encapsulated between glass sheets, and their main US manufacturer operates its own takeback recycling program.
• Under the EPA's leaching test — panels crushed, soaked in acid, and agitated, a deliberately worst-case procedure — most panels test as non-hazardous. Results are not uniform: some panels have exceeded limits for lead or cadmium, sometimes varying within the same model line.
• An intact, operating panel emits nothing. The meaningful questions are about breakage and disposal, which is why decommissioning terms — not chemistry — are where county negotiations actually land.
• Recycling now recovers up to 95% of a panel's materials at scale; the largest US recycler processed over a million panels in 2025. The barrier is economics, not technology: recycling runs $20–30 per panel against $1–2 for landfill.

What's Actually in a Solar Panel

A standard crystalline silicon module is roughly three-quarters glass by weight, with an aluminum frame, a plastic backsheet and encapsulant, silicon cells, copper wiring, and silver contact lines. The trace material that drives most toxicity discussion is lead — used in solder at less than 0.1% of panel weight — comparable to the solder in consumer electronics, and laminated inside glass rather than exposed to weather.

Cadmium enters the conversation because of a different technology: cadmium telluride (CdTe) thin-film panels, roughly 5% of the market and used mainly in large utility projects. CdTe is a stable compound sealed between glass layers, not loose cadmium metal, and First Solar — the dominant CdTe manufacturer — runs a takeback and recycling program for its own modules. Conflating the two panel types is the most common factual error in hearing-room testimony, in both directions.

What the Leaching Tests Show

The federal standard is the Toxicity Characteristic Leaching Procedure (TCLP): the panel is crushed, bathed in an acidic solution, and agitated — simulating decades in an unlined landfill, not a hailstorm in a field. Panels are consistently characterized as non-hazardous under this procedure in most published testing.

The honest caveat: results vary. Peer-reviewed reviews of PV toxicity testing report that some panels have exceeded TCLP limits for lead or cadmium — occasionally with different results from the same manufacturer and model line. That variability is why end-of-life panels are regulated and tested rather than waved through, and it is a fair point for a county to raise. What it does not support is the groundwater-poisoning claim: the failure mode being tested is a crushed panel sitting in landfill acid, not an intact panel standing on racking. A panel in a field that cracks gets detected by monitoring, de-energized, and replaced — its economics guarantee that, since a broken panel produces no revenue.

What Happens When Panels Wear Out

Panels degrade slowly — typically well under 1% of output per year — and carry 25- to 30-year warranties, with many expected to produce beyond that. Most panels retired today come out early, from storm damage or repowering, not old age.

The recycling industry that barely existed five years ago is now real. Solarcycle, the largest US dedicated recycler, achieves roughly 95% material recovery and processed more than one million panels in 2025, with plans to double that in 2026. Recovered glass, aluminum, silicon, silver, and copper feed back into manufacturing; the Department of Energy puts the cumulative value of recoverable materials at about $450 million globally by 2030.

The obstacle is price, not physics: recycling a panel costs roughly $20–30 versus $1–2 for landfill disposal. That gap is closing as volumes rise and recovered-material markets mature, and several states now restrict landfilling panels outright. Until the economics fully flip, the mechanism that actually guarantees responsible disposal is contractual — which brings the question back to the county negotiating table.

Decommissioning: Where the Real Protection Lives

Modern county ordinances — including many logged in our Opposition Tracker — require decommissioning plans backed by bonds or escrow before a project is approved: the developer posts financial security sufficient to remove every panel, post, and cable and restore the land, priced by an independent engineer and revisited on a schedule. Utility-scale solar sits on driven piles rather than deep foundations, so restoration is genuinely feasible in a way it rarely is for heavier industry.

For residents worried about end-of-life outcomes, the productive hearing-room question is not "are panels toxic?" — it is "what does the decommissioning bond cover, who holds it, and how often is it re-priced?" Those terms, not chemistry claims, determine what a county is left with in 2055. See our moratorium explainer and state-by-state restriction data for how these conditions are being written across the country.

Frequently Asked Questions

Do solar panels contain cadmium?

About 95% of panels — the crystalline silicon type — contain no cadmium. The roughly 5% that do (cadmium telluride thin-film, used mostly in utility projects) hold it as a stable compound sealed between glass sheets, and the dominant manufacturer operates a takeback recycling program.

Can solar panels leach chemicals into groundwater?

An intact panel emits and leaches nothing in operation. The EPA's worst-case leaching test — crushing panels and soaking them in acid — finds most panels non-hazardous, though published results vary and some panels have exceeded lead or cadmium limits. The scenario that test simulates is landfill disposal, which is exactly what decommissioning bonds and state disposal rules exist to manage.

Can solar panels be recycled?

Yes — up to about 95% of a panel's material by weight is recoverable at commercial scale, and the largest US recycler processed over a million panels in 2025. Recycling still costs more than landfilling ($20–30 versus $1–2 per panel), which is why contractual decommissioning requirements matter until the economics close the gap.

Sources: US EPA (end-of-life solar panel regulations, recycling, and FAQ pages); US Department of Energy Solar Energy Technologies Office; peer-reviewed toxicity-testing reviews in Waste Management (2023); Solarcycle; NREL cost analyses. Facts verified July 27, 2026. Free to cite with attribution and a link. Terms explained in our Clean Energy Glossary.