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Cadmium: The Dark Side of Thin-Film?

The future of the solar power industry may be bright, but solar also has a dark side — the panels being built today have an estimated lifespan of 30 to 40 years and then are largely discarded. The problem with that is that some thin-film photovoltaic solar cells contain hazardous substances like cadmium that can pose a health risk if the solar panel is simply thrown out after it’s done soaking up the sun. The issue is important enough that in late October, the Silicon Valley Toxics Coalition (SVTC), which lobbies to keep old computer parts from being dumped, plans to release a report raising concerns about cadmium in solar panels and urging manufacturers to reclaim old panels to keep cadmium out of the waste stream.

Only about 1 percent of electrical generation globally comes from solar today, but that is expected to grow to 20 or 40 percent by 2020, according to McKinsey & Co. SVTC cites forecasts such as that to argue that the solar industry should develop best practices now to ensure solar panel makers take responsibility for the product lifecycle.

“The writing is pretty much on the wall that solar panels have materials in them that need to be recovered because some of them are hazardous,” said Shelia Davis, executive director of the SVTC. Although relatively few solar panels have reached end of life, she’s concerned that when more of them are retired, they could end up with other construction debris in landfills.

Cadmium, a byproduct of copper, lead and zinc mining, can be really bad for humans and the ecosystem. It’s a toxic metal that can cause kidney and breathing problems, according to the U.S. Labor Department. The European Union has also banned cadmium from being used in batteries and electronics.

Cadmium is used in one of the leading new thin-film PV panel types, but as a compound that manufacturers argue is much safer than cadmium alone. Thin-film solar leader First Solar uses cadmium-telluride to make the semiconductors that are sandwiched between two sheets of glass to convert the sunlight into electricity. So do newer startups like AVA Solar.

Cadmium-telluride (called cad-tel for short) is a more cost-effective way of making thin-film PVs than the older crystalline silicon design. AVA Solar’s vice president of marketing, Russell Kanjorski, said cad-tel is a compound that renders the cadmium inert, reducing the risk of contamination versus cadmium alone. Tests by the National Renewable Energy Laboratory showed that cad-tel would have to be heated to 1,041 degrees Celsius before it breaks down. Most roof fires burn at temperatures of 800-900 degrees.

Nonetheless, OSHA labels cad-tel a hazardous material that must be handled with caution in the manufacturing process as if it were cadmium, Kanjorski added. And when it starts shipping its first solar panels, AVA Solar will set aside a certain amount of money from each sale to fund a reclamation program. “You don’t want to be a green company but then leave a problem 30 or 40 years from now,” he noted. First Solar also offers a reclamation program.

At this point AVA and First Solar seem to be in the minority. Reclamation programs are a low priority for startups focused more on raising capital and building production, pointed out Graham Stevens, associate director of the energy practice at Navigant Consulting. “It’s not surprising that on the cadmium telluride side some of the smaller companies that are startups are not as focused on the environmental issues,” he said. Stevens anticipates many will eventually develop reclamation programs once their businesses mature.

Cad-tel thin film panels are poised for strong growth as the overall solar industry grows. The thin-film solar panel market grew 126 percent in 2007, over 2006, primarily due to growth of the cad-tel product, according to Navigant research. The two other thin film types are copper indium gallium selenide (CIGS), which has one-hundredth the amount of cadmium as cad-tel, and amorphous silicon, which contains no cadmium, said Stevens.

Ultimately, that’s the purpose of the forthcoming SVTC report: to deal with cad-tel now before it gets too big. The SVTC’s Davis says she intends for her report to draw attention to the problem and encourage solar panel makers to deal with end-of-life issues for their products now.

11 Responses to “Cadmium: The Dark Side of Thin-Film?”

  1. While cadmium is toxic your efforts are futile and a waste of time. The truth is cadmium is used as a catlyist in the production of synthetic rubber. Infact if you live in the city you probably breath the shit in all day. If you have a garden with wood chips from trees growing alog the roadside or a garden along a road there a hell of alot of cadmium accumulation over the decades. When a flourescent light breaks do you call a hazmat team. The truth is the panels must be recycles like all hazardous materials. Think about this how many radios and computes have you thrown in the dump in your lifetime. If its more than six you contaminated your drinking water with enough cadmium to dope enough solar panels to heat your house, charge a solar car, and run you brun coffie maching Dude….

  2. ablazev

    Cadmium is the 6th most dangerous toxic carcinogen heavy metal on Earth. No matter how you look at it, it is still a potential killer. And especially when spread over thousands of acres desert land, baking all day and freezing all night. The Cadmium thin films will go through the mechanical and chemical changes, as would any thin film combo. They will disintegrate and decompose and nobody knows what exactly will happen in these mega-fields after 10-20 years. The manufacturers don’t have data to support their shallow claims of the environmental and health safety of Cadmium in the desert mega-fields, and yet they dare take a chance. A chance that these Cadmium mega-fields will convert the desert lands into hazmat dumps and our neighborhoods into guinea pigs test farms. And, of course, we’ll let the next generation deal with it–just like we did with Lead, Asbestos, Nicotine and crude oil. And this time in the name of “green” energy!

  3. Cadmium recycling can be a lucrative business. One of the only 2 cadmium “producers” in the United States does its entire business extracting cadmium from NiCd batteries. I suspect something similar will develop extracting Cd from dead panels.


  4. David King

    Government will have a huge role in how fast solar grows and hence the rate of the resulting pollution problem.

    The European Emission Trading Scheme allows companies to buy and sell pollution permits. Than there’s the Kyoto agreement (for everyone BUT the US), emission taxes (UK is considering), tax credits (Bush in the US).

    There’s a lot of opportunity for corruption. Companies getting paid for being ‘green’ can easily skew the numbers and fake it.

    But if solar is expected to be cheaper than other forms of electricity by say 2020, it may be sooner with government paying people for being green.