Solar Waste Stream is Tiny, Compared to Current Fossil Fuels

Now published in Nature Physics, the answer to unfounded claims about huge amounts of solar panel waste.
Regular readers here will have seen my interviews with the authors some months ago.
You’re welcome.

See Above for useful Figure 1 from the paper. BTW, for much, much more on these and other topics related to solar energy, see my website Sun101.org.

Mirletz, Hieslmair, et al in Nature Physics:

Unsubstantiated claims that fuel growing public concern over the toxicity of photovoltaic modules and their waste are slowing their deployment. Clarifying these issues will help to facilitate the decarbonization that our world depends on.
PV modules are new to many people, so increasing PV deployment has led to growing concerns about the quantity of waste that may arise from decommissioning them (if they are not recycled), and their potential to leach toxic metals. Debunking misinformation about PV modules and PV module waste is the first step in addressing these concerns that are unnecessarily slowing PV deployment².

Articles that raise concerns about PV module waste typically cite a prediction from the 2016 IRENA end-of-life report³ that 60 million metric tons of cumulative PV module waste will be produced by 2050. Since that report, module lifetimes have increased from 12 years to over 35 years through accelerated testing and improved standards. However, estimates of the required PV capacity have increased dramatically, to 75 TW by 2050. We have updated these projections (shown on the right-hand side of Fig. 1) to take these two factors into account. These new estimates show the best-case and worst-case scenarios for cumulative PV module waste are between 54 million and 160 million metric tons cumulatively by 2050⁴.

Although this seems like a large amount of waste, Fig. 1 shows that 35 years of cumulative PV module waste (2016–2050) is dwarfed by the waste generated by fossil fuel energy and other common waste streams (if we assume constant annual waste at present rates). For example, if we do not decarbonize and transition to renewable energy sources, coal ash and oily sludge waste generated from fossil fuel energy would be 300–800 times and 2–5 times larger, respectively, than PV module waste. Also, both coal ash and oily sludge are known to be toxic^5,6. In fact, we globally produce and manage approximately the same mass of coal ash per month as the amount of PV module waste we expect to produce over the next 35 years. Compared another way, globally we will generate up to 440–1,300 times more mass of municipal waste than PV module waste by 2050.

Incorrect information about toxic materials in PV modules is leading to unsubstantiated claims about the harms that PV modules pose to human health and the environment, fuelling public concern and opposition to PV development². For example, several US state health department websites provide a list of potential toxins in PV modules, including arsenic, gallium, germanium and hexavalent chromium^7,8,9,10. However, the vast majority of PV modules are either crystalline silicon or cadmium telluride (CdTe) (97% and 3% global market share, respectively, in 2022).

In fact, these two most common types of PV contain almost none of these harmful materials. Crystalline silicon PV modules are 77% glass, 10% aluminium, 3% silicon and 9% polymers, with less than 1% copper, silver and tin, and less than 0.1% lead¹¹. CdTe modules are 80–85% glass, 11–14% aluminium, 2–4% polymers, less than 0.4% copper, and less than 0.1% tellurium and cadmium¹¹.

We have not found any evidence that either of these PV technologies contain arsenic, gallium, germanium, hexavalent chromium or perfluoroalkyl substances. Arsenic and gallium are used in only high-efficiency PV modules for aerospace applications. Germanium was once used in some amorphous silicon modules that were never produced at scale. We cannot find any evidence that chromium was ever used in PV modules outside of laboratory cells in the 1970s. We believe that hexavalent chromium is listed because it was once used for plating chrome onto solar thermal water heaters (not photovoltaics). Finally, while some backsheets are fluoropolymer-based, free perfluoroalkyl substances are not present in PV modules¹².

The International Energy Agency confirmed that the only potential human health and environmental concerns in commercially produced PV modules are the trace amounts of lead in the solder of crystalline silicon modules and the cadmium in CdTe modules¹³. While the <15-μm-thick solder coatings of wires and ribbons in a crystalline silicon module contain small fractions of lead, this risk may be reduced as many manufacturers are seeking to adopt lead-free solders¹⁴. The CdTe compound in commercially available thin-film solar modules is extremely stable and does not pose the same toxicological hazard as elemental cadmium. The thin CdTe film (typically they are less than 3 μm thick) means that the total amount of cadmium is less than 0.1% by weight¹¹. CdTe modules are currently collected and both cadmium and tellurium are recycled into new modules.

Below, the authors on Lead in Solar panels:

Here, some notes on Cadmium, a purported concern for some types of panels, from a highly useful pub out of North Carolina State U.

Health and Safety Impacts of Solar Photovoltaics, North Carolina State University:

Traditionally a tin-based solder containing some lead (Pb) is used, but some manufacturers have switched to lead-free solder. The glass frit and/or the solder may contain trace amounts of other metals, potentially including some with human toxicity such as cadmium. However, testing to simulate the potential for leaching from broken panels, which is discussed in more detail below, did not find a potential toxicity threat from thesetrace elements. Therefore, the tiny amount of lead in the grass frit and the solder is the only part of silicon PV panels with a potential to create a neg- ative health impact. However, as described below, the very limited amount of lead involved and its strong physical and chemical attachment to other components of the PV panel means that even in worst-case scenarios the health hazard it poses is insignificant.
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Traditionally a tin-based solder containing some lead (Pb) is used, but some manufacturers have switched to lead-free solder. The glass frit and/or the solder may contain trace amounts of other metals, potentially including some with hu- man toxicity such as cadmium. However, testing to simulate the potential for leaching from broken panels, which is discussed in more detail below, did not find a potential toxicity threat from thesetrace elements. Therefore, the tiny amount of lead in the grass frit and the solder is the only part of silicon PV panels with a potential to create a negative health impact. However, as described below, the very limited amount of lead involved and its strong physical and chemical attachment to other components of the PV panel means that even in worst-case scenarios the health hazard it poses is insignificant.
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Questions about the potential health and environmental impacts from the use of this PV technology are related to the concern that these panels contain cadmium, a toxic heavy metal. However, sci- entific studies have shown that cadmium telluride differs from cadmium due to its high chemical and thermal stability.19 Research has shown that the tiny amount of cadmium in these panels does not pose a health or safety risk. Further, there are very compelling reasons to welcome its adoption due to reductions in unhealthy pollution associat- ed with burning coal. Every GWh of electricity gen- erated by burning coal produces about 4 grams of cadmium air emissions. Even though North Car- olina produces a significant fraction of our elec- tricity from coal, electricity from solar offsets much more natural gas than coal due to natural gas plants being able to adjust their rate of production more easily and quickly. If solar electricity offsets 90% natural gas and 10% coal, each 5-megawatt (5 MWAC, which is generally 7 MWDC) CdTe solar facility in North Carolina keeps about 157 grams, or about a third of a pound, of cadmium out of our environment.