Most solar panels contain no cadmium at all. Cadmium lives in cadmium telluride (CdTe) thin-film modules, while crystalline silicon modules, which account for the large majority of installed capacity, carry lead in their solder instead. Get that one fork wrong and everything downstream goes wrong with it: the sampling plan, the transport paperwork, the receiving facility, the cost. The volume behind the question keeps growing.
This guide is written for the people who actually have to make the call: EPC contractors closing out a repower, O&M teams clearing a laydown yard, utility asset managers signing a decommissioning scope. It covers which modules contain cadmium, how a hazardous waste determination gets made, how the semiconductor film is actually recovered, what worker exposure looks like in practice, and which rules apply in which jurisdiction. Recycling cadmium from solar panels is a narrow technical problem wrapped inside a much broader compliance problem, and the two are usually confused.
The terms you need before anything else
Anyone reading a quote for cadmium solar panel recycling or a letter from a state agency runs into the same dozen terms. Here they are, defined so each one stands on its own.
Cadmium telluride (CdTe). A compound semiconductor made of cadmium and tellurium, used as the light-absorbing layer in one family of thin-film modules. The film is only a few micrometers thick and sits sealed between two sheets of glass. It is a stable crystalline compound, not loose cadmium metal.
Crystalline silicon (c-Si). The dominant module technology, built from wafer-based silicon cells connected by soldered ribbon. A c-Si module contains glass, an aluminum frame, silicon, copper, silver and a small quantity of lead in the solder. It does not contain cadmium.
Thin-film module. A module in which the active semiconductor is deposited as a thin coating on glass or a flexible substrate rather than cut from a wafer. CdTe and CIGS are the two commercially significant chemistries.
CIGS (copper indium gallium selenide). The other commercial thin-film chemistry. Some CIGS devices, and some older CdTe designs, include a very thin cadmium sulfide layer in the stack, which is why CIGS cannot be waved through as cadmium-free without checking the datasheet.
Cadmium sulfide (CdS) buffer layer. A nanometer-scale window layer that sits between the transparent conductive oxide and the absorber. NREL describes intermediate layers such as CdS as helping “both the growth and electrical properties between the TCO and CdTe.” Many current products have moved to cadmium-free buffers, so this is a per-model question.
EVA encapsulant. Ethylene vinyl acetate, the polymer that laminates the cell stack between glass and backsheet. It is engineered to survive 25 years of weather, which is exactly why it resists separation at end of life. The encapsulant is the single biggest physical obstacle in cadmium telluride recycling and in c-Si recycling alike.
TCLP. The Toxicity Characteristic Leaching Procedure, the federal laboratory test that simulates leaching in a landfill. EPA states that heavy metals like lead and cadmium “may be leachable at such concentrations that waste panels would fail the toxicity characteristic leaching procedure (TCLP), a test required under RCRA.”
RCRA D006. The federal hazardous waste code for cadmium under the toxicity characteristic. The regulatory level in 40 CFR 261.24 is 1.0 mg/L. The equivalent code for lead is D008 at 5.0 mg/L, which is why a crystalline silicon module can be a hazardous waste even though it contains no cadmium.
Universal waste. A lighter set of RCRA rules for widely generated hazardous wastes, with lighter storage, labeling and transport requirements than full hazardous waste management. Solar panels are not federally universal waste today.
Semiconductor layer recovery. The step in CdTe module recycling that strips the thin film off the glass and puts the cadmium and tellurium into solution so they can be separated and precipitated as usable compounds.
Tellurium recovery. The economic reason the semiconductor step exists. Tellurium is scarce, and the USGS reports it is recovered “principally as a byproduct of the electrolytic refining of primary copper,” with solar power cells taking an estimated 70 percent of global consumption in 2025.
WEEE Directive. The EU framework for waste electrical and electronic equipment. Photovoltaic panels are named explicitly in its categories and are flagged in Article 5 as a priority stream for separate collection.
Which solar panels actually contain cadmium
The identification step in cadmium solar panel recycling takes ten minutes and saves weeks. Cadmium is present in CdTe thin-film modules, where it is chemically bound as cadmium telluride, and in the trace cadmium sulfide buffer used in some CIGS and older thin-film designs. It is not present in crystalline silicon modules, whether monocrystalline or polycrystalline.
Three checks settle it in practice. Read the module datasheet or nameplate, which states the cell technology. Look at the module face: a c-Si module shows discrete square or pseudo-square cells with visible busbar lines, while a CdTe module reads as a uniform dark sheet with fine scribe lines and typically no metal frame on the long edges. Then check the manufacturer, because CdTe production is concentrated in a small number of producers and First Solar is by far the largest of them.
CdTe is not a fringe technology. NREL describes CdTe cells as the largest segment of thin-film production worldwide, and CdTe modules are common in US utility-scale plants specifically. So on a large decommissioning project the honest answer is usually “some of both,” and the sort order matters more than the label.
On real sites the paperwork is rarely clean. At The Solar Recycling Company the intake for commercial panel decommissioning asks EPC and O&M teams for make, model, quantity, condition and location before anything is loaded, because thin-film solar panel recycling and crystalline silicon processing follow different downstream routes and mixed pallets are the norm rather than the exception. Where module types are unknown, they get sorted at receipt rather than guessed at in the field.
Is a cadmium-containing solar panel hazardous waste?
Sometimes. That is the accurate answer and it frustrates everyone who wants a yes or no.
EPA is unusually blunt on this point: “Some solar panels are considered hazardous waste, and some are not, even within the same model and manufacturer.” A module is a federal hazardous waste when a representative sample exceeds a toxicity characteristic regulatory level under the TCLP. For cadmium that is code D006 at 1.0 mg/L. For lead it is D008 at 5.0 mg/L. A CdTe module can fail on cadmium. A crystalline silicon module can fail on lead. Both, or neither, can pass.
The duty to decide sits with the generator, not the recycler. EPA’s guidance states that “it is the responsibility of the generator of the solar panel waste to determine if the solar panels are hazardous by performing the appropriate tests (i.e., the TCLP) or by using generator knowledge.” Generator knowledge is a legitimate route: if you already know from prior testing of the same make and model that the panels exceed the limits, you can declare them hazardous without new analysis. When knowledge is thin, EPA says “TCLP testing would be required to make the hazardous waste determination.”
What follows from a failed test is the expensive part. Generators of panels that exceed the limits must manage them under 40 CFR Parts 262 through 268 as hazardous waste, with manifests, permitted transporters and permitted receiving facilities, unless the panels are repaired, reused or recycled. That exclusion is why cadmium solar panel recycling is usually the cheaper compliance path rather than the more expensive one. Sending a failing module to a permitted hazardous waste landfill costs more, and it destroys the recoverable material at the same time.
Two practical notes. TCLP results vary with sample preparation, so ask any laboratory how the module was reduced before extraction. And a determination made on one lot does not automatically travel to another lot from a different plant or vintage.
How cadmium is recovered from solar panels, step by step
CdTe module recycling is a wet chemical process bolted onto a mechanical front end. Each step below stands alone.
- Intake and chemistry identification. Pallets arrive and every lot is identified by technology before anything is opened, because cadmium solar panel recycling and crystalline silicon processing part ways at this gate. Modules are separated into crystalline silicon and thin-film streams, and thin-film is separated again into CdTe and CIGS where the datasheet allows. Damaged and broken modules are segregated at this stage because they are handled with dust controls the intact stream does not need. Documentation for the hazardous waste determination is attached to the lot here, not later.
- Frame, junction box and cable removal. Aluminum frames, junction boxes, cabling and connectors are removed mechanically. Framed modules are de-framed on a press or a manual station; many CdTe modules are frameless glass-glass laminates and skip most of this. Aluminum and copper leave the process at this point as clean, high-value metal streams. Removing them first keeps them out of the leaching chemistry, where they would contaminate the recovery of cadmium and tellurium compounds.
- Size reduction. The laminate is crushed and then milled to a controlled particle size, usually in an enclosed circuit under negative pressure with dust capture. Size reduction serves the chemistry: it exposes the semiconductor film so leaching liquor can reach it, and it breaks the glass free of the encapsulant. This is the step where airborne particulate risk is real, which is why enclosure and extraction are not optional in hazardous material recovery from PV modules.
- Delamination and encapsulant handling. The EVA encapsulant holds the sandwich together and must be defeated thermally, mechanically or chemically. Thermal routes burn or pyrolyse the polymer, mechanical routes shear it off with the glass, and solvent routes swell and dissolve it. Each has a tradeoff between glass quality and energy use. The encapsulant is the reason thin-film solar panel recycling is more than shredding: the polymer that made the module last 25 years is what makes it hard to take apart.
- Semiconductor film leaching. The milled material is contacted with an acidic oxidising leach, commonly a sulfuric acid and hydrogen peroxide system, which dissolves the cadmium and tellurium off the glass surface into solution. Residence time, temperature and solid to liquid ratio govern how completely the film is stripped. The output of this step is a loaded liquor plus clean glass cullet, and the two are separated by filtration or settling.
- Precipitation and separation of cadmium and tellurium. The pregnant liquor is treated in stages to drop the metals out selectively. Tellurium is typically reduced and precipitated first, then cadmium is precipitated, usually as a hydroxide or carbonate, by raising pH. The precipitates are filtered, washed and dried into a saleable or further-refinable product. Cadmium telluride recycling is economically interesting because tellurium is scarce, not because cadmium is valuable.
- Glass cleaning and recovery. The stripped glass is rinsed, neutralised and screened to remove residual polymer, film and interlayer fines. Recovered cullet is the largest mass fraction of any module by a wide margin and goes to glass manufacturing, insulation or aggregate depending on residual contamination. Glass quality is where a recycling operation makes or loses money, so the cleaning stage gets more attention than the name suggests.
- Residue management and documentation. Filter cake, spent liquor, polymer residues and dust collection fines are characterised and routed to permitted downstream handlers. Nothing that carries a hazardous characteristic gets blended away. Hold any vendor to the same standard on paper: no material stream in a commercial solar panel recycling report should be described with a generic verb like “disposed of.” Ask them to name the metal, name the permitted downstream handler that received it, and hand you the record for the file.
Recovery rates: how much of a CdTe module is actually recovered
Mass and value point in different directions on a thin-film module, and quoted recovery rates mean nothing until you know which one is being measured.
By mass, glass dominates. A CdTe laminate is overwhelmingly glass, with the semiconductor film contributing a vanishingly small fraction of total weight. So a high mass recovery number is mostly a statement about glass, not about cadmium or tellurium. By value, the semiconductor film and the metals carry the load, and a process that recovers 95 percent of the mass while dumping the film has not really done cadmium telluride recycling at all.
The best-documented closed loop in this space is the manufacturer take-back route. First Solar, which is the dominant CdTe producer, states that its process recovers more than 90 percent of module materials for reuse, and it distinguishes its approach from bulk recycling by adding closed-loop semiconductor recovery for use in new modules. That distinction is the one to ask any vendor about: bulk mass recovery and semiconductor recovery are different services.
Against that, the wider US picture is far less flattering. Trade coverage of the American end-of-life problem puts the volume already heading toward retirement at an estimated one million tons of modules by 2030 and roughly ten million tons by 2050, with a large share of discarded panels still going straight to landfill. It is tough to be proud of how environmentally friendly renewable energy is if the back end of it turns into a pollution problem, and that gap between the technical capability and the actual practice is the whole reason this article exists.
Safety and worker exposure during handling
Intact modules are not an exposure hazard. The semiconductor film in a CdTe module is sealed between glass sheets, and EPA’s own guidance notes that working solar panels do not leach those toxic metals because the encapsulant protects them. Nobody standing next to an operating array is inhaling cadmium. Field crews doing removals on intact glass are in the same position.
Risk enters with breakage, grinding and heat, which is to say it enters on a CdTe module recycling line rather than on a roof. Once glass is fractured and material is milled, cadmium-bearing particulate can become airborne, and that is a regulated occupational exposure. OSHA’s cadmium standard at 29 CFR 1910.1027 sets a permissible exposure limit of 5 micrograms per cubic meter of air as an eight-hour time-weighted average, with an action level of 2.5 micrograms per cubic meter that triggers monitoring and medical surveillance obligations. Those numbers apply to a processing floor, not to a rooftop.
What that means operationally is straightforward. Handle cracked and shattered modules as a separate stream from day one and do not let a broken pallet ride with intact stock. Wrap and contain broken glass rather than sweeping it. Keep size reduction inside enclosed equipment with local exhaust ventilation and particulate capture. Run air monitoring against the action level rather than assuming compliance. Keep eating, drinking and smoking off the processing floor, since ingestion of settled dust is a real pathway. Provide and launder work clothing so cadmium dust does not leave the site on a jacket.
California’s universal waste rules for PV modules are explicit about the line between these activities, distinguishing “dismantling of PV modules without intentionally breaking the PV module glass” from “processing PV modules by intentionally breaking the PV module glass.” That is a useful mental model even outside California. The moment you intend to break glass, you are running an industrial process and the controls need to match.
The regulations that apply: federal, state and international
There is no single federal solar panel recycling law in the United States. What exists is a hazardous waste framework that catches some panels, plus a patchwork of state programs. The table below is the working set for anyone scoping cadmium telluride recycling or a mixed-technology decommissioning.
| Framework | Applies to | What it requires | Where |
|---|---|---|---|
| RCRA toxicity characteristic | Any discarded module that fails TCLP | Generator determination by testing or generator knowledge; hazardous waste management under 40 CFR 262 to 268 unless repaired, reused or recycled. Cadmium is D006 at 1.0 mg/L, lead is D008 at 5.0 mg/L | Federal, all 50 states |
| Federal universal waste | Not yet applicable to solar panels | EPA announced a rulemaking effort on 23 October 2023 to improve management of end-of-life solar panels; panels are not federally universal waste in the meantime | Federal, pending |
| State universal waste for PV modules | Discarded modules managed by a handler | Lighter storage, labeling and transport rules; the handler must still perform a hazardous waste determination when the module is discarded | California, effective 1 January 2021 |
| State universal waste for solar panels | Discarded modules | State-adopted universal waste standards for solar panels | Hawaii |
| Photovoltaic Module Stewardship and Takeback Program | Module manufacturers selling into the state | Manufacturer must have a state-approved stewardship plan; the legislature moved the deadline from 1 July 2025 to 31 January 2031 | Washington |
| WEEE Directive | Producers placing modules on the EU market | Photovoltaic panels are named in the directive’s equipment categories and flagged in Article 5 as a priority for separate collection; a 2024 amendment confirmed producers bear the cost of managing and disposing of modules placed on the market after 13 August 2012 | European Union |
| National guidance on retired equipment | Wind and PV equipment reaching end of life | State Council guidance issued 17 August 2023 lists “establishing and improving the responsibility mechanism for the disposal of decommissioned equipment” among its key tasks; this is guidance rather than a producer take-back mandate on the WEEE model | China |
Two things fall out of that table for anyone scoping commercial solar panel recycling. First, in most of the country, the only rule that bites is the federal toxicity characteristic, and the duty to apply it sits with you, the generator. Second, the state picture is moving. Washington’s stewardship deadline slid by more than five years, which means anyone still telling you that Washington mandates manufacturer take-back today is working from stale information. Verify the current date before you build a plan around it. In California, state-specific recycling requirements shape how cadmium solar panel recycling projects are staged, while in states with no dedicated program, such as our coverage across Texas, the RCRA determination is the whole of the compliance question.
Your options for a cadmium-containing module
Four routes exist. Two of them are not really routes.
Manufacturer take-back. If the modules are CdTe and the manufacturer runs a recycling program, this is often the highest-recovery form of cadmium telluride recycling available, because the semiconductor goes back into new modules. First Solar operates the best known example. Ask about geographic coverage, freight responsibility and whether the offer applies to modules the manufacturer did not sell you.
A specialist PV recycler. The route for mixed fleets, off-brand thin film, and any project where crystalline silicon and CdTe arrive on the same trucks. Ask which certifications the vendor holds, request the certificate scope and expiry in writing, ask where each material stream physically goes, and ask for the recovery split by mass and by material rather than a single headline percentage.
A universal waste handler. In California and Hawaii, a permitted handler can accept modules under the lighter universal waste standards, which simplifies storage and transport. It does not remove the determination duty when the module is finally discarded.
Curbside or landfill. Neither works. Municipal recycling programs do not accept photovoltaic modules, and dropping a pallet at a transfer station moves liability rather than resolving it. Landfilling a module that fails TCLP is a hazardous waste disposal event with the paperwork that implies.
There is a fifth option that gets skipped: do not recycle a module that still works. A great deal of what comes off a repower has years of production left, and reuse beats recovery on both economics and carbon. The Solar Recycling Company buys used and excess solar panels from EPCs, utilities and asset owners and resells inspected modules to commercial buyers, precisely so that commercial solar panel recycling is applied to the panels that genuinely need it, not to every pallet on the site.
What it costs and who pays
The cost of recycling cadmium from solar panels is driven by four things: chemistry, condition, distance and volume. Thin-film modules requiring semiconductor recovery cost more to process than plain crystalline silicon. Broken modules cost more than intact ones because they need containment. Freight is frequently the largest single line item, and it is charged by weight on a product that is mostly glass. Volume changes everything, because a full truckload amortises mobilisation across hundreds of modules.
The recycling prices we publish for commercial work run about $20 to $50 per panel plus shipping, and value recovered from resaleable equipment offsets part of that. Nobody planned for this cost when these plants were financed, which is exactly why it lands as a surprise on decommissioning budgets. The way to reduce it is not to shop for the cheapest per-panel number. It is to sort aggressively at the site so that resale, standard recycling and hazardous handling each get only the modules that belong in them.
On who pays for recycling cadmium telluride panels: in the United States, absent a state stewardship program, the asset owner pays. Under the EU WEEE model, producers carry the financing obligation. That difference is the single biggest structural gap between the two markets.
Frequently asked questions
Do all solar panels contain cadmium?
No. Cadmium is present in cadmium telluride thin-film modules and in the trace cadmium sulfide buffer layer used in some CIGS and older thin-film designs. Crystalline silicon modules, which make up the large majority of installed capacity, contain no cadmium; their regulated metal is lead in the solder, which is why commercial solar panel recycling has to sort by technology before it sorts by anything else.
Are solar panels toxic if they break?
A broken module sitting in a yard is not releasing meaningful cadmium into the air. EPA notes that working panels do not leach their toxic metals because the encapsulant protects them. The exposure risk appears when glass is deliberately broken, milled or heated, which is why processing facilities run enclosed equipment and monitor against OSHA’s cadmium action level.
Can I put solar panels in curbside recycling?
No. Curbside and municipal recycling programs do not accept photovoltaic modules. Commercial solar panel recycling volumes go to a specialist recycler, a manufacturer take-back program, or a universal waste handler in states that allow it.
How do I document a hazardous waste determination for a batch of thin-film modules?
Write it down before the pallets move. A defensible file has four parts: the module inventory, meaning make, model, quantity and condition; the basis of the determination, either TCLP results from an accredited lab on a representative sample or generator knowledge backed by the manufacturer’s own material information; the resulting waste codes, or the reasoned finding that no toxicity characteristic applies; and the date and the name of whoever made the call. Keep the sampling plan with it, because on a mixed thin-film load the first thing anyone asks is how the sample represented the batch. If you are relying on generator knowledge for cadmium solar panel recycling, hold the manufacturer document that supports it rather than a link to a page that can change.
Does First Solar recycle its own panels?
Yes. First Solar, the dominant CdTe manufacturer, runs dedicated recycling operations for its own thin-film modules and states that the process recovers more than 90 percent of module materials for reuse, including closed-loop semiconductor recovery. Coverage and commercial terms vary by region, so confirm both before planning around it.
Is cadmium telluride the same as cadmium metal?
No, and the distinction matters. Cadmium telluride is a stable crystalline compound with different physical and toxicological properties from elemental cadmium, and in a module it is sealed between glass. Regulatory tests such as the TCLP measure what leaches under defined conditions, not how much cadmium is present, which is why two modules with identical cadmium content can produce different results.
What happens to the recovered cadmium?
At the end of cadmium telluride recycling, the cadmium is precipitated out of solution as a compound, filtered, washed and dried, then sold or sent for further refining. Recovered tellurium goes back toward semiconductor feedstock. Any fraction that cannot be refined is characterised and routed to a permitted downstream handler with documentation of where it went.
Key takeaways
Chemistry first, everything else second. Only CdTe thin-film modules and some CIGS designs contain cadmium. Crystalline silicon modules carry lead instead, and can still fail a hazardous waste test on that basis.
The determination is yours. EPA puts the hazardous waste determination on the generator, by TCLP testing or by documented generator knowledge, not on the recycler who receives the pallet.
Recovery rate is two numbers, not one. In thin-film solar panel recycling, mass recovery is mostly glass. Semiconductor recovery is what actually returns cadmium and tellurium to use, and vendors should be asked about both.
Broken glass changes the job. Intact modules pose no inhalation risk. Milling and thermal processing do, and OSHA’s cadmium limits apply on the processing floor.
State rules move. Washington’s manufacturer stewardship deadline has been pushed to 2031, California and Hawaii run universal waste routes, and there is still no federal universal waste rule for panels.
Closing the loop on a module that was never designed to come apart
The uncomfortable truth of recycling cadmium from solar panels is that the module was engineered to survive weather for a quarter century, and every property that makes it durable makes it stubborn at end of life. That is a solvable engineering problem, and it is being solved. What is not solved is the habit of treating end-of-life planning as an afterthought, which is how a plant that spent its whole life generating clean power ends up as a pallet of unsorted glass in a landfill.
Whoever you hire, ask for the determination method, the material routing and the recovery split, in writing, before a pallet leaves the site. Those three answers tell you more about a recycler than any capability deck will. The people behind this page came out of electronics recycling and have been handling commercial solar panel recycling since the company was founded in 2019.
If you are an EPC, O&M provider, utility or asset owner facing a decommissioning or repower with thin-film modules in the mix, The Solar Recycling Company handles commercial and utility-scale solar panel recycling and asset recovery nationwide, including recycling cadmium from solar panels and the documentation that goes with it, on projects of 100 panels and up.
