Is Solar Waste a Problem?

A data-driven analysis of solar's waste problem compared to other energy sources

Photo by Quang Nguyen Vinh

In rural communities across the United States, local residents are rejecting solar farms because of fears about their waste. 

The idea has taken root among citizens’ groups fighting local solar proposals. Last year, fears that toxins would leach out of solar panels and contaminate soil and groundwater helped kill an Ohio solar project. In other communities, this narrative is fueling efforts to ban new solar farms outright.

Right-wing nonprofits—including many who receive money from fossil fuel donors—have seized on the opportunity, amplifying the message.

But a recent analysis of solar waste reveals that the problem is being exaggerated and stripped of important context. 

Putting solar waste in context

Solar panels have finite lifetimes. They typically work well for about 25 to 35 years. When they break or become too degraded for normal use, they’re recycled, repurposed or thrown away. Today, due to the high cost of recycling and the limited market for used panels, the vast majority of decommissioned solar panels end up in landfills.

In 2016, IRENA found that cumulative global photovoltaic waste would reach an estimated 60 million metric tons by 2050. No matter how you slice it, 60 million metric tons of waste is a lot. That’s the weight of 180 Empire State Buildings. It’s like throwing away about 350 billion iPhone 14s.

But according to an analysis by researchers at NREL that was published last month in the journal Nature Physics, the scale of photovoltaic waste is tiny compared with that of the rest of the global waste stream. 

The Nature Physics article notes that in the years since the 2016 IRENA report, solar panels’ lifetimes have gotten a lot longer, but the total solar capacity projected to be built as part of the energy transition has “increased dramatically.” The authors project that by 2050, cumulative global photovoltaic waste will fall somewhere in the range of 54 to 160 million metric tons.

But, unlike many past studies, the NREL researchers put this number in context of the broader waste stream. They estimate that over that same period, the world will have to deal with approximately 70 billion metric tons of municipal waste, 46 billion metric tons of coal ash, 12 billion metric tons of plastic waste, 2 billion metric tons of electronic waste, and 249 million metric tons of oily sludge.

Even in the worst-case scenario, coal will still be responsible for roughly 285 times more waste than solar between now and 2050. But the researchers estimate that there could be as much as 850 times more waste from coal than from solar over that period.

There’s also a lot of momentum behind efforts to expand recycling efforts and make the process more affordable as early solar installations continue to come offline, an option that has yet to prove scalable for fossil fuel byproducts like coal ash and oily sludge.

Solar waste isn’t as toxic as fossil fuel byproducts

And then there’s the other side to the controversy over photovoltaic waste.

The 2016 IRENA report identified lead, indium, gallium, selenium, cadmium and tellurium as human health hazards linked to solar panels. It warned that “[t]he risk that materials will leach out of the end-of-life product or its components to the environment is very significant.”

Other widely circulated lists of dangerous solar panel components have tacked on things like arsenic, germanium, hexavalent chromium, and perfluoroalkyl substances, better known as PFAS.

NREL’s researchers examined this problem, too. They found that the problem of toxic waste is much smaller than once thought. 

Virtually all of the solar panels sold globally are made with just two types of photovoltaic modules. “We have not found any evidence,” the authors write, “that either of these PV technologies contain arsenic, gallium, germanium, hexavalent chromium or perfluoroalkyl substances.”

They add that, according to the International Energy Agency, “the only potential human health and environmental concerns” in commercial photovoltaic modules are trace amounts of lead in some panels and a relatively stable cadmium compound in others.

The latter makes up just 3% of the global photovoltaic market. It’s already possible for the cadmium and tellurium in those solar panels to be recovered, recycled, and kept out of landfills entirely.

Coal ash, oily sludge, and electronic waste are all laden with many dangerous toxins and aren’t always disposed of properly, putting communities near power plants, refineries, and landfills at risk.

Towards the end of their analysis, NREL’s researchers call on the solar industry to invest in longer-lasting panels and better recycling programs. Recycling, they argue, will be key to decarbonizing the PV supply chain and reducing waste. 

However, they conclude, “Placing the expected PV module waste stream in context, the transition to replace fossil-based energy with renewables represents a substantial reduction in mass and toxicity of waste.”

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