Like all e-waste, the deluge of aging solar panels is concerning as they reach their end-of-life. By 2030, we’re expected to see over 8.8 million tons of waste from photovoltaic panels (PVs). But there’s one panel technology, in particular, that carries some fairly nasty and dangerous materials. Called cadmium telluride thin film photovoltaics, or CdTe, they’re relatively low-cost to manufacture, effective, and make up over 30% of the U.S. PV market. They have a lifespan of 20 to 30 years, but some of the oldest were installed in the early 2000’s. That means we’re coming up on their expiration date soon, and they cannot be tossed away like common trash.
If these panels end up in landfills, moisture can carry toxins from the cadmium and tellurium — referred to as landfill leachate — and enter the groundwater, exposing the area to potential toxins. The chemicals are distributed inside a panel as a thin, solid semiconductor layer, but something like rainwater coming into contact with it can build up and leach the toxins. Of course, that’s less likely to happen if the panels remain intact, unbroken, and sealed, or if the facility has proper leachate mitigation, but there’s no guarantee of that when tossed into a disorderly landfill. 
It’s not the panels themselves that are the problem, but rather the materials inside. Solar farms of all kinds are having a hugely positive effect on local wildlife, and the broader environment, when they’re in use. But since a whopping 90% of expired or defective panels end up in landfills after they’ve run their course — it costs less to dump than recycle — the concerns are warranted.
There are teams of researchers that have developed ways to properly recycle and dispose of the materials inside the CdTe panels. By using electrochemical solutions the cadmium and tellurium can be extracted. The big problem is that these methods require specialized solutions, and the infrastructure for building and sustaining facilities on a large scale isn’t quite there yet. Then there’s the matter of education. While it’s easier and less costly to throw the resulting panels in a landfill, that’s absolutely not what should be happening. Everyone needs to understand how to properly and safely deal with old panels.
The EPA recommends that homeowners contact state and local recycling agencies for guidance on how to dispose of them. There are some smaller recyclers that can take in CdTe panels, and some companies, like First Solar, develop their technologies from the get-go so they’re suitable for recycling. Around 90% of the materials in First Solar’s modules can be recovered and reused after they reach end-of-life.
With proper care and maintenance, the expected lifecycle of the average solar panel is formidable. It takes around 30 years for them to lower to 80% efficiency, which means, you may not even need to replace them completely by that time. Many panels being purchased, installed, and put into use today have a distant expiration. But if you do have old panels, understanding how and where your local regulations apply is important. You can also find creative ways to repurpose old solar equipment, but you’ll still want to be mindful of the hazards.
The EPA recognizes cadmium is a toxic substance, and considers it to be carcinogenic. Tellurium has been known to cause damage to organs in both rats and humans. Therefore, it is ill advised to expose yourself to potential toxins, which means staying away from broken, shattered, or damaged PVs. Exposure to cracked cells may even warrant cancer screenings.
If you’re near solar panels or working around them, it’s a smart idea to wear the proper protective equipment, including gloves, coverings, and even respirators. The Occupational Safety and Health Administration (OSHA) recommends wearing eye and face coverings and physical protective equipment around solar hardware. OSHA also recommends periodic inspections and tests of solar panel facilities. 
This is all going to be very different for residential folks, and if you’re a homeowner working on or with your own solar setup. It’s likely to be just you with no one else measuring or testing before you get to work. But it’s important to be aware that you could be working with dangerous and toxic materials so that you can take the necessary precautions.

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