Solar panels can and do release small quantities of metals and other chemicals into surrounding soil and water, though the risk depends heavily on whether a panel is intact or broken, which technology it uses, and how it is disposed of at end of life. The most studied concern is lead, which is present in the solder of mainstream crystalline silicon panels and as a core ingredient of next-generation perovskite cells. Cadmium, tellurium, copper, nickel, and other metals round out the list depending on panel type. Under normal operating conditions, leaching is minimal. The trouble starts when panels crack, land in acidic landfill environments, or sit broken in a field after a storm.
What Chemicals Are Actually in Solar Panels
The vast majority of panels installed worldwide are crystalline silicon (c-Si). They are mostly glass, aluminum, and silicon by weight, but they also contain small amounts of lead in the solder that connects cells together, plus copper wiring and trace silver. A standard testing procedure found that a c-Si module exceeded the EPA’s regulatory limit for lead in leachate, registering about 20 mg/L against a limit of 5 mg/L.1Current Opinion in Green and Sustainable Chemistry. Assessment of toxicity tests for photovoltaic panels: A review That said, not every panel fails the test. A database of 97 samples across 33 modules from 16 manufacturers found less than an 8% chance that a traditionally manufactured panel would exceed EPA lead limits when sampled using the standard practice, though the authors cautioned the sample size was small.2PubMed. Photovoltaic module leach testing: Database development and statistical analysis
Thin-film panels use different active materials. Cadmium telluride (CdTe) panels, the second most common type globally, contain cadmium and tellurium. Copper indium gallium selenide (CIGS) panels carry copper, indium, gallium, and selenium. Each technology has a distinct leaching profile, and the risks are not interchangeable.
How Leaching Happens During Normal Use
An intact, well-mounted solar panel sitting on a rooftop is essentially a sealed sandwich of glass, polymer encapsulant, and metal. Metals inside the laminate cannot easily reach the outside world unless the encapsulant degrades or the glass cracks. Over decades, the encapsulant (usually ethylene-vinyl acetate, or EVA) can slowly break down under UV exposure and heat, producing acetic acid that may gradually corrode internal components.3Solar Energy Materials and Solar Cells. Acetic acid production and glass transition concerns with ethylene-vinyl acetate used in photovoltaic devices Modeling approaches that account for real field conditions like crack size, exposure time, glass thickness, and the chemical properties of the metals inside the panel suggest that some metal release is plausible over a panel’s 25- to 30-year lifespan, but the quantities are far smaller than what escapes from broken panels or panels that end up in landfills.4Journal of Cleaner Production. Life cycle analysis of metals in emerging photovoltaic (PV) technologies: A modeling approach to estimate use phase leaching
The practical takeaway for a homeowner or solar farm operator is that an undamaged panel on a well-maintained system is unlikely to contaminate the soil beneath it in any meaningful way. The picture changes when panels break or reach end of life.
Landfill Conditions Make a Big Difference
When panels are discarded and end up in a landfill, the chemistry of the surrounding environment matters enormously. A study that simulated landfill conditions for CdTe thin-film panels found stark differences depending on the phase of decomposition. In the acidic phase of a landfill, a continuous-flow column released about 73% of the cadmium and 21% of the tellurium over 30 days. The dissolved cadmium concentration was more than three times the standard toxicity test limit and roughly 650 times the EPA’s maximum contaminant level for cadmium in drinking water. But in the later methanogenic phase, when the landfill chemistry shifted to less acidic and less oxidizing conditions, cadmium and tellurium release was negligible.5PubMed Central. Leaching of cadmium and tellurium from cadmium telluride (CdTe) thin-film solar panels under simulated landfill conditions
Here is where things get tricky for policymakers. The standard EPA test used to classify hazardous waste, called the Toxicity Characteristic Leaching Procedure (TCLP), is a batch test that exposes crushed material to a mildly acidic solution for a short period. It is designed to simulate one snapshot of landfill conditions, not the full lifecycle of decomposition. The continuous-flow experiment described above suggests that the TCLP may underestimate what actually happens during the acidic phase of a real landfill. Yet a separate year-long study found something surprising in the opposite direction: when panels were soaked in actual landfill leachate collected from a real site, metal release was minimal compared to synthetic test solutions.6PubMed. Metal dissolution from end-of-life solar photovoltaics in real landfill leachate versus synthetic solutions: One-year study Real landfill chemistry is messy. Organic matter, competing ions, and microbial activity all affect how much metal actually dissolves. The synthetic worst-case scenarios used in labs do not always match what happens in the ground.
This tension between lab tests and field reality runs through the entire literature on solar panel leaching. The honest summary is that lab conditions can overestimate or underestimate real-world release, depending on which phase of landfill chemistry you simulate and how you set up the experiment.
Broken Panels in Soil
Panels do not always make it neatly into a landfill. Some end up buried, dumped, or left in soil after being discarded illegally or damaged beyond repair. When corroded and degraded thin-film panels were buried directly in soil, heavy metals including zinc, copper, nickel, gallium, lead, indium, and chromium leached out at rates that depended on how much panel material was in the soil and on the soil’s own chemistry.7Applied Geochemistry. Release of metal pollutants from corroded and degraded thin-film solar panels extracted by acids and buried in soils Acid contact time and acid concentration both increased the amounts dissolved, which means that naturally acidic soils or soils receiving acid rain would see more contamination.
A risk assessment that modeled the soil and groundwater contamination from end-of-life panels found significant soil contamination with aluminum, silver, cadmium, iron, and lead, while groundwater contamination remained relatively low. Lead posed a notable cancer risk from soil exposure across all scenarios modeled, though the non-cancer risk from other metals via groundwater stayed within acceptable bounds.8PubMed. Ecological and human health risk assessment of metals leached from end-of-life solar photovoltaics The implication is that improper disposal in open soil is a more concerning pathway than a well-managed landfill with a liner and leachate collection system.
Storm Damage and Fire
Severe weather is the scenario that worries researchers the most, because it can break many panels at once and leave them exposed to rain for days or weeks before anyone collects them. Real-world data from several events illustrates the scale. Hurricane Maria, a Category 5 storm, damaged only about 0.002% of modules at a Puerto Rican solar farm. But a 2019 hailstorm at a North Carolina site cracked the glass on more than half the panels; initial visual inspection caught only 31%, and ultraviolet imaging later revealed the true figure was closer to 51.5%.9Cell Press. Environmental and health risks of perovskite photovoltaic technology: A review Cracked glass does not mean all the metals wash out immediately, but it opens a pathway for rain to reach internal components, and the longer broken panels sit in the field, the greater the potential for leaching into the soil below.
Fire is a different kind of exposure. When panels burn, volatile metal compounds can become airborne. An early risk analysis of cadmium telluride, copper indium diselenide, and gallium arsenide panels concluded that the health risks from fire were generally not large for residential-scale systems. For commercial-scale installations, the authors recommended simple precautions like alerting residents within a kilometer or two to stay indoors and close windows during a fire.10Solar Cells. Toxic materials released from photovoltaic modules during fires: Health risks For perovskite panels, experiments showed that heating a panel to 760°C caused the perovskite to decompose into lead iodide, which then oxidized into lead oxide. However, having a glass cover on both sides of the module effectively contained the lead fumes.11Matter. Tackling lead toxicity and leakage in perovskite solar cells
Modeling what happens if perovskite panels broke catastrophically at a utility-scale site found that most of the lead gets sequestered in soil rather than traveling to groundwater or air. Even under worst-case assumptions, the lead concentrations from the perovskite film itself fell well below EPA limits in both groundwater and air. Background lead already present in the soil was actually a bigger factor in whether a site would exceed regulatory limits than the lead contributed by the panels.12PubMed. Fate and Exposure Assessment of Pb Leachate from Hypothetical Breakage Events of Perovskite Photovoltaic Modules
What Happens to Wildlife and Ecosystems
Even if leaching concentrations seem low in a regulatory sense, they can still affect living organisms. Lab studies using zebrafish embryos and other test species have found measurable toxic effects from panel leachates. CIGS cell leachates produced under simulated acidic rain caused delayed hatching and heart edema in zebrafish embryos, along with changes in genes related to oxidative stress and hormone activity. When researchers added a chemical that binds metal ions, the effects disappeared, confirming that the dissolved metals were the culprit.13Science of the Total Environment. Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells
A comparative study that tested leachates from both perovskite and conventional silicon-based cells found an unexpected result: the silicon panel leachates were actually more toxic to fish embryos than the perovskite ones, with lead and silicon content both contributing to the toxicity.14PubMed. Comparative toxicity of potential leachates from perovskite and silicon solar cells in aquatic ecosystems Another study found that solution leached from broken conventional panels released nickel at potentially toxic concentrations and caused developmental defects in both plants and aquatic animals.15Environmental Pollution. Potential toxicity of improperly discarded exhausted photovoltaic cells These studies consistently show that broken panels in contact with water can produce leachates capable of harming aquatic life. The findings are worth noting even if the real-world concentrations reaching a pond or stream would be diluted relative to the lab conditions.
Perovskite Panels and the Coming Lead Problem
Perovskite solar cells are not yet widely deployed, but they are among the most actively researched next-generation technologies because they can be manufactured cheaply and have reached impressive efficiencies in the lab. The catch is that the most successful perovskite formulations contain lead as an essential ingredient, and perovskite films are far less chemically stable than silicon. Moisture can intrude into the perovskite core and cause degradation, potentially releasing lead compounds into the environment.16PubMed Central. A review of lead leakage monitoring in perovskite solar cells: emerging detection technologies, just transition to clean energy and perspectives This instability is the central challenge holding the technology back from commercial deployment.
The modeling work on catastrophic breakage of perovskite modules found reassuring numbers for groundwater and air, but the soil pathway remains a concern depending on what background contamination already exists at a given site.12PubMed. Fate and Exposure Assessment of Pb Leachate from Hypothetical Breakage Events of Perovskite Photovoltaic Modules Researchers are developing real-time lead leakage monitoring tools to track any release before it accumulates, and some groups are working on lead-free perovskite formulations using tin or bismuth. So far, though, the lead-free versions have not matched the efficiency of their lead-based counterparts.
Lead-Free Solder and Other Mitigation Strategies
For the crystalline silicon panels already on the market, the most direct path to reducing leaching risk is switching from lead-based solder to lead-free alternatives. A life cycle analysis of candidate alloys found that tin-silver-copper and tin-zinc solders work for mainstream panel designs, while tin-bismuth-silver alloys suit newer low-temperature soldering approaches. The study’s key finding was that raw material sourcing drives environmental impact more than the manufacturing process itself. Scarce materials like silver and indium carry high environmental costs. And simply removing lead does not automatically improve a module’s overall environmental footprint, because the replacement materials bring their own impacts.17Solar Energy. Lead-free solder alloys for PV modules: Life cycle assessment for environmental impact and toxicity
On the mechanical performance side, a tin-bismuth alloy with 0.4% silver by weight showed good wettability, strong initial bonding, and less than 5% power loss during thermal cycling tests, making it a viable drop-in replacement for lead solder in certain panel designs.18Solar Energy Materials and Solar Cells. Interconnection of low-temperature metallization on silicon solar cells – The role of silver in tin-bismuth-based solder alloys The industry is moving, albeit slowly. The EU’s Restriction of Hazardous Substances directive has exempted photovoltaic panels from its lead ban for years, partly because reliable lead-free alternatives were not available. As the solder science matures, that exemption may eventually tighten.
Recycling is the other major lever. Life cycle assessments consistently show that upcycling end-of-life panels outperforms both downcycling and landfilling across impact categories including human toxicity, climate change, and water eutrophication.19Journal of Cleaner Production. Overview of life cycle assessment of recycling end-of-life photovoltaic panels: A case study of crystalline silicon photovoltaic panels When panels are properly recycled, the metals are recovered and reused rather than left to leach into the ground. The challenge is building out recycling infrastructure fast enough to handle the wave of panels that will reach end of life in the 2030s and 2040s.
Solar Farms on Contaminated Land
An interesting flip side to the leaching question is what happens when solar panels are deliberately installed on already-polluted land. In coal mining subsidence areas, agrophotovoltaic systems that combine panels with specific plant species reduced soil contamination indices by 25 to 35%. The shade and moisture changes created by the panels drove different plants toward different cleanup strategies: one species concentrated metals in its roots, stabilizing them in place, while another pulled metals upward for removal.20PubMed. Photovoltaic arrays as ecological engineers: Microclimate-driven functional divergence for synergistic soil remediation in coal mining subsidence areas On metal-polluted agricultural land used for solar power, three seasons of phytoextraction under panels cut soil cadmium concentrations by about 60% and zinc by about 31%.21Journal of Cleaner Production. Sustainable phytoextraction of metal-polluted agricultural land used for commercial photovoltaic power generation In these cases, solar installations are not adding contamination but actively helping clean it up, a point that rarely surfaces in public debates about panel toxicity.
Dust Hazards When Panels Are Recycled
The leaching story focuses on what panels release into soil and water, but there is also a workplace exposure question. When panels are mechanically crushed during recycling, the initial step produces relatively low levels of airborne dust and negligible toxic metal aerosols because the solder and encapsulant act as shock absorbers. The risk shifts downstream. When the crushed material is ground further and blended into aggregate for reuse, the respirable dust fraction surges to roughly 39 to 73% of total dust, carrying whatever metals were in the original panel along with it.22Hygiene. Occupational Hygiene Assessment of Airborne Dust Exposure in the Solar Panel Recycling and Downstream Reuse Industry This “hazard transfer” from one stage of recycling to another is a relatively new finding and one that regulators and recycling facility operators are only beginning to address. Workers in secondary grinding and blending operations need dust controls and respiratory protection that may not yet be standard at every facility handling end-of-life panels.