Concerns About Solar Panel Waste and Toxicity Unwarranted: It’s a Manageable Problem (For Now)

 

     Many articles in the late 2010s and early 2020s were sounding the alarm about the upcoming deluge of solar panel waste but the reality is that the amount of waste produced by solar panels is manageable and makes up about 5% of the total waste generated as e-waste. Solar panel waste is often considered a form of e-waste. A new paper in Nature Physics by researchers at the NREL and the Colorado School of Mines forecasts that it will make up from 2.9% to 8.5% of the total e-waste by 2050. The total amount of all e-waste in 2050 is expected by the authors to make up just 4% of the total coal ash waste. The graphic below from the paper shows the various waste streams by volume. If the graphic is anywhere near accurate it shows that the volume of solar waste won’t be a major issue.

Source: Unfounded concerns about photovoltaic module toxicity and waste are slowing decarbonization. Heather Mirletz, Henry Hieslmair, Silvana Ovaitt, Taylor L. Curtis & Teresa M. Barnes. Nature Physics volume 19, pages1376–1378 (2023). Unfounded concerns about photovoltaic module toxicity and waste are slowing decarbonization | Nature Physics

 

     A 2017 article in The National Review cited Michael Shellenberger’s Environmental Progress (EP) report about solar panel waste, which noted that solar panels produce 300 times more toxic waste per unit of energy than nuclear power plants. This is not surprising since nuclear waste volumes are very small compared to other waste streams and nuclear energy is extremely energy-dense while solar is not. However nuclear waste is clearly far more toxic. Solar panels often contain cadmium, chromium, and lead. The EP researchers pointed out that panels were often burned to extract the copper wires for salvage value (a problem with many types of e-waste) creating carcinogenic smoke. The solar industry disputed the dangers then as it does now. It said then that solar panel waste could be disassembled without burning and the materials recycled, or the panels could be reused in other applications. The National Review article also mentioned the use of smartphones replacing many other consumer electronics having the net effect of reducing e-waste volumes. Smartphones are a great example of a phenomenon known as dematerialism where they can replace in a single electronic device what in the past would have required many other devices: calculators, cameras, video cameras, flashlights, home phones, radios, TVs, PCs, watches, GPS systems, magnifying glasses, audio recorders, and many more devices. Solar panel manufacturing also produces contaminated water and sludge which is disposed of at hazardous waste facilities.

     Shellenberger, in a 2018 Forbes article, harped on the dangers of cadmium washing out of broken solar panels by rainwater. That is a concern with some solar waste. Most can be disposed of in regular landfills, but some require hazardous waste landfills. At the time, solutions to help mitigate solar panel e-waste included fees in producers for future disposal costs and recycling mandates. A huge amount of e-waste has been shipped overseas where it is picked through by human salvagers.

 

Recycling Solar Panels

     Solar panel recycling is a fledgling industry now, but it is expected to grow significantly in the coming years. One issue with solar panel waste recycling vs. e-waste recycling is that standard processes for e-waste recycling often don’t work with solar panel recycling. Silver and silicon recovery are important in solar panel recycling and require special methods to extract. Research is ongoing by the DOE and others to find breakthroughs in solar recycling. By late summer 2020, the EU had solar panel recycling mandates in place and Japan, Australia, and India had plans for requirements. The U.S. only had mandates in Washington state. According to a 2020 article in Wired (originally in Grist) “Right now, we’re pretty confident the number is around 10 percent of solar panels recycled,” said Sam Vanderhoof, the CEO of Recycle PV Solar, one of the only US companies dedicated to PV recycling. The rest, he says, go to landfills or are exported overseas for reuse in developing countries with weak environmental protections.” The article cites others who say the cost to recycle solar panels exceeds the revenue by as much as 10 to 1. A more recent article suggests that the cost difference is about 4 to 1, $5 to dispose of in a landfill vs. $20 to recycle. Efficient extraction of the silver and silicon could improve the economics, Veolia in France shreds and grinds the panels and uses an optical technique to recover low-grade silicon. Recycle Solar is using a process from their European partners that extracts 95% of low-purity silver and silicon. New heat and chemical recycling techniques aim to increase extraction and lower costs.

     Another approach is to design solar panels with recyclability, refurbishment, and remanufacturing in mind. Now, in 2023, NREL estimates that less than 10% of solar panels are being recycled. Recycling requires specialized facilities. Over 90% end up in municipal landfills simply because it is cheaper. There are too few solar recycling facilities in operation now in the U.S., only five. Even in the EU, the recycling rate is just 10%. That is fine for now, but more recycling capacity will be needed in the future as the amount of retired solar panels increases in the 2030 to 2050 period. The graph below is from a 2016 analysis but is expected to remain close to reality. With a big thrust in solar deployment in the mid-late 2020s there will be a corresponding big thrust in solar panel waste in the 2050s. By then, we should have the efficiencies of recycling worked out much better.

 

     The International Renewable Energy Agency (IRENA) 2016 report estimated the value of recovered materials from recycling solar panels at $15 billion by 2050. A later study by Rystad Energy predicts the value will hit $15 billion by the late 2030s and nearly $80 billion by 2050. The most abundant materials in solar panels are aluminum and glass. Glass makes up nearly 80% of most solar panels by weight. However, the glass quality is often not good enough to have resale value to glass companies. Glass also has the most potential for reuse where crushed solar panel waste can be used to replace sand as aggregate in certain concrete applications such as pavement. One study found that glass from spent solar panels could replace aggregate or cement by up to 10% in concrete used for pavement construction without negatively affecting compressive strength. Imperfect glass blends can be used in glass sandblasting. Silicon, silver, and copper only make up 3% by weight but have most of the resale value. Recovered silver and aluminum are expected to have the highest values by volume, followed by copper.

     While the development of a circular economy is often hyped, without incentives and mandates it will be slow to develop. In the meantime, the process of recycling is not economical so if that were to happen now, the question arises as to who will pay for it. It would make solar more expensive for the consumer as costs were passed on.

     It used to be said that the average life of a solar panel was 20-25, sometimes 30 years. More recently it is pegged at 30-40 years. Some of that extended life could be due to reusing old and degraded panels for other applications. That longer life would mean less waste.

 

Re-Using Old and Degraded Solar Panels

     Solar panels from decommissioned utility-scale solar farms often have plenty of life left in them and can be resold at a great discount to certain buyers. RV owners can buy refurbished solar panels for a bargain that may have 10 years of life left in them. Of course, their efficiency is degraded. Sellers use photo luminescence to check for integrity issues like cracks. The panels need a thorough inspection to assess resale value. Since many grid-scale projects likely have regular panel replacement schedules built into their economic models when their efficiency drops to a certain level, large sets of panels of similar age and level of degradation are likely obtainable and fairly easily prepped for resale.  There are also markets for used or refurbished solar panels overseas in developing countries, where they are unlikely to ever be recycled for materials, aside from possibly copper.  

 

Retired Solar Panel Toxicity

     The degree of toxicity of used-up solar panels is still in dispute and mired in uncertainty. That creates issues for the disposers, who are not sure if their waste is toxic or not. The IEA determined that the risk to human health of non-hazardous or hazardous landfill disposal of panels from leaching of cadmium, lead, and selenium was low, but they did not directly endorse the process. NREL is still working on risk assessments. Older solar panels, those retiring now, are more likely to be toxic, although just a small percentage of them. The authors of the Nature Physics paper did not find any examples of utility-scale solar panels that contained arsenic, gallium, germanium, or hexavalent chromium. A small share of panels contained trace amounts of cadmium, but in a stable form of it, not considered a danger to human health. The cadmium toxicity risk is thus likely overblown. There are different types of solar panels with different chemical compositions. Whether they are determined to be hazardous wastes or not depends on the composition of the panels and their condition. Broken panels are more likely to be considered hazardous.

     The Florida Department of Environmental Protection has a fact sheet on managing unwanted or broken solar panels that involves the determination of whether they should be considered hazardous or not. Basic components of all electronic devices are considered as well. Potential toxicity depends on levels of hazardous components:

 

“In general, data shows that older silicon panels can be hazardous due to lead solder. Some older silicon panels are hazardous for hexavalent chromium coatings. Cadmium tellurium (CdTe) panels are typically hazardous due to the cadmium. Gallium arsenide (GaAs) panels can be hazardous due to the arsenic. Thin film panels, such as copper indium gallium selenide (CIS/CIGS) panels, can be hazardous due to the selenium.”

 

“The electronic components associated with the solar panels (e.g., drivers, inverters, circuit boards) contain all of the common electronic device hazardous constituents such as lead, arsenic, cadmium, selenium and chromium.”

 

Dangers Overblown

 

Anti-renewable energy activists and pundits like to emphasize the problem and dangers of solar panel waste and toxicity, but it does appear that this is mostly a myth and a manageable problem, at least for now.

 

References:

A Reality Check About Solar Panel Waste and the Effects on Human Health. Dan Gearino. Inside Climate News. October 12. 2023. A Reality Check About Solar Panel Waste and the Effects on Human Health - Inside Climate News

Unfounded concerns about photovoltaic module toxicity and waste are slowing decarbonization. Heather Mirletz, Henry Hieslmair, Silvana Ovaitt, Taylor L. Curtis & Teresa M. Barnes. Nature Physics volume 19, pages1376–1378 (2023). Unfounded concerns about photovoltaic module toxicity and waste are slowing decarbonization | Nature Physics

Solutions for Solar Panel Waste Are Just Beginning to Surface. Tree Meinch. Discover Magazine. August 3, 2023. Solutions for Solar Panel Waste Are Just Beginning to Surface | Discover Magazine

NREL Explodes Solar Panel Waste Myths. Steve Hanley. Clean Technica. October 13. 2023. NREL Explodes Solar Panel Waste Myths - CleanTechnica

If Solar Panels Are So Clean, Why Do They Produce So Much Toxic Waste? Michael Shellenberger. Forbes. May 23. 2018. If Solar Panels Are So Clean, Why Do They Produce So Much Toxic Waste? (forbes.com)

A Clean Energy’s Dirty Little Secret. Julie Kelly. National Review. June 28, 2017. Solar-Panel Waste: Environmental Threat from Clean Energy | National Review

Solar panel waste is not the worst thing that’s ever happened. Jon Smieja. Green Biz. June 24, 2022. Solar panel waste is not the worst thing that’s ever happened | GreenBiz

Solar Panel Recycling Is About To Become BIG Business! Steve Hanley. Clean Technica. July 17, 2022. Solar Panel Recycling Is About To Become BIG Business! - CleanTechnica

Making Solar Energy as Clean as Can Be Means Fitting Square Panels Into the Circular Economy. Emma Peterson and Wyatt Myskow. Inside Climate News. October 9, 2023. Making Solar Energy as Clean as Can Be Means Fitting Square Panels Into the Circular Economy - Inside Climate News

Solar Panels Are Starting to Die, Leaving Behind Toxic Trash. Maddie Stone. Wired. August 22, 2020. Solar Panels Are Starting to Die, Leaving Behind Toxic Trash | WIRED

As Millions of Solar Panels Age Out, Recyclers Hope to Cash In. Jon Hurdle. Yale Environment 360. February 28, 2023. As Millions of Solar Panels Age Out, Recyclers Hope to Cash In - Yale E360

Managing Unwanted or Broken Solar Panels in Florida. Florida Department of Environmental Protection. MANAGING UNWANTED OR BROKEN SOLAR PANELS IN FLORIDA (floridadep.gov)

Solar panels replace sand in concrete production. Henry Ballard. Quarry Magazine. January 28, 2022. Solar panels replace sand in concrete production - Quarry (quarrymagazine.com)

Applications of Solar Panel Waste in Pavement Construction—An Overview. Malindu Sandanayake 1, Le Li, Junhai Zhao, and Paul Joseph. Sustainability. 2022, 14(22), 14823. November 10, 2022. Sustainability | Free Full-Text | Applications of Solar Panel Waste in Pavement Construction—An Overview (mdpi.com)