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Solar Module Materials and Disposal

by | Apr 7, 2023

Solar modules consist primarily of glass and aluminum and are tightly sealed to protect the solar cells from dust and moisture. Modules can contain environmentally sensitive materials such as lead, cadmium, selenium, and silver in semiconductors and electrical contacts. Analysis conducted by the International Energy Agency found that even in a worst-case disposal scenario – with broken panels exposed to acidic conditions in an unlined landfill – levels of lead, cadmium, and selenium were at least an order of magnitude below the EPA’s health screening values in the soil, air, and water. Federal agencies, industry groups, and Vermont stakeholders, led by REV and the Agency of Natural Resources, are all working to expand reuse and recycling opportunities for solar modules.

What’s in a Solar Module?
Glass and aluminum constitute the vast majority of the material in a solar modular – 97% of the module’s total mass. Most solar cells are made of silicon but some are made with cadmium and other materials. Lead, cadmium, selenium, and silver can all be found in solar modules and can present health and environmental hazards.

Do Solar Modules Pose Risks to Human Health?
The International Energy Agency has examined the potential human health impacts of solar modules that break while installed and after modules have been disposed of in a landfill.[1][2] Both of the assessments looked at worst-case scenarios – rainwater leaching through broken panels at a solar facility and broken panels exposed to acidic conditions in an unlined landfill (which are illegal in the United States) – and reported that levels of lead, cadmium, and selenium released under these conditions where below the EPA’s safety thresholds. While this analysis is not a comprehensive study of all of the materials used in solar modules, based on these reports, the National Renewable Energy Labs concluded that panel breakage and disposal did not motivate concerns from a toxicity/hazardous materials perspective.[3]

What’s a Solar Module’s Life Expectancy and what happens when they cease to operate?
Solar panels are typically warranted for 20 to 25 years. Many solar panels continue to operate well beyond this warranty period. Nonetheless, as the rate of solar installation grows, there is increasing interest in how to manage solar panels after they are decommissioned to ensure that valuable materials are reused and landfilling is minimized. The current waste streams from solar are very small but they are projected to grow significantly. Even as far out as 2050 solar modules will constitute a small fraction of the electronic waste that we will need to manage.

Federal and Industry Recycling Initiatives
The federal government has invested heavily in bringing down the cost of solar module recycling and removing other barriers to recycling. In 2022, the Department of Energy released an “end-of-life action plan” that includes additional data collection on module components and research into solar recycling technologies with a goal of reducing recycling costs by more the 50% by 2030.  The National Renewable Energy Laboratory has also been studying barriers to solar module recycling and identified regulatory uncertainty and variability from jurisdiction to jurisdiction as a challenge for recycling. REV supports a federal policy approach, such as extended producer responsibility law, to encourage module recycling.

Other barriers to recycling is the cost of transporting panels and low prices for recycled glass. The Solar Energy Industry Association is working to develop networks for aggregating panels from multiple sites and to grow downstream markets for recycled materials to address these barriers.

REV and VT ANR Recycling Initiatives
Renewable Energy Vermont (REV) and the Vermont Agency of Natural Resources (ANR) are collaborating to host a discussion series among stakeholders in the renewable sector, waste management, and state government to explore end-of-life disposal for solar power and battery storage equipment in Vermont with the goal of developing Best Management Practices for solar modules in Vermont.

[1] P. Sinha, G. Heath, A. Wade, K. Komoto. (2019) Human health risk assessment methods for PV, Part 2: Breakage risks, International Energy Agency (IEA) PVPS Task 12, Report T12-15:2019. ISBN 978-3-906042-87-9.

[2] P. Sinha, G. Heath, A. Wade, K. Komoto. (2019) Human health risk assessment methods for PV, Part 3: Module disposal risks, International Energy Agency (IEA) PVPS Task 12, Report T12-16:2020. ISBN 978-3-906042-96-1.

[3] Curtis, Taylor, Garvin Heath, Andy Walker, Jal Desai, Edward Settle, and Cesasr Barbosa. (2021) Best Practices at the End of the Photovoltaic System Performance Period. Golden, CO: National Renewable Energy Laboratory. NREL/TP-5D00-78678.

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