Solar panels do not become useless in 25 years and need to be discarded, do not leach toxic chemicals, and do not contain cadmium. They do contain small amounts of lead, but leaching metallic lead out of landfills is very difficult and probably does not ever happen unintentionally.
'The most common reason that solar panels would be determined to be hazardous waste would be by meeting the characteristic of toxicity. Heavy metals like lead and cadmium may be leachable at such concentrations that waste panels would fail the toxicity characteristic leaching procedure (TCLP)'
'Today, roughly 90 percent of panels in the U.S. that have lost their efficiency due to age, or that are defective, end up in landfills because that option costs a fraction of recycling them.'
Yes, all of that is correct as far as it goes, and isn't in contradiction with what I said. You'll notice that the EPA page you linked https://www.epa.gov/hw/end-life-solar-panels-regulations-and... is mostly about an effort to reclassify solar panels as non-hazardous waste, which is specifically because of what I said. See for example https://www.sciencedirect.com/science/article/pii/S030147972... "About 8% of traditional PV samples exceed the 5 mg/L limit for Pb in TCLP tests.
No modern PV samples exceed the 5 mg/L limit for Pb in TCLP tests."
But TCLP is already an extremely rigorous test, far worse than nearly all actual landfills, intentionally. It uses acetic acid, one of the very few acids that forms a soluble salt of lead, and none of the anions present in normal soils that normally immobilize lead, such as carbonate, phosphate, sulfate (!), and chloride.
And air pollution from pyrometallurgical recycling of the kilogram quantities of lead from car batteries is totally irrelevant to the safe containment of the milligram quantities of lead from (probably hydrometallurgical) recycling of solar panels. I am really struggling to imagine how your understanding of the issue could be so shallow that you thought it might be relevant.
Scrap lead is like US$1/kg. Nobody is going to recycle solar panels for that.
