The Solar Panel Recycling Dilemma: How to Sacrifice Value for Environmental Protection (Report)

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The dilemma of solar panel recycling lies in sacrificing their value for environmental protection, according to Al-Energy, a specialized energy platform based in Washington.

To this end, researchers conducted an assessment of the environmental and economic performance of recycling strategies for frameless, double-glass solar panels encapsulated with flexible polyolefin, a design that is increasingly being used in bifacial solar panels.

The researchers note that most studies on solar panel recycling have focused on conventional panels encapsulated with ethylene vinyl acetate, featuring a plastic backsheet and an aluminum frame.

Meanwhile, the international research team compared three scenarios for recycling a complete solar panel weighing approximately 27 kilograms.

Recycling Solar Panels: 3 Scenarios

The first scenario relied on the thermal and chemical treatment of the entire solar panel, according to a report published in PV Magazine.

The second scenario employed mechanical processing and selective treatment, limiting thermal processing to specific components.

The third scenario added further fractionation after thermal treatment, using electrostatic separation under vacuum.

Each scenario was evaluated using two chemical pathways for metal extraction: sodium hydroxide followed by ammonia and hydrogen peroxide, and nitric acid with hydrogen peroxide.

The researchers described the work as a preliminary comparative study based on previous laboratory-scale recycling results, conducting a comprehensive life cycle assessment of the product, including the avoidance of primary raw materials, using midpoint indicators of the ReCiPe 2016 life cycle impact assessment methodology.

On the other hand, the economic assessment was based on a process-level operating margin, derived from revenues from extracted materials and selected operating costs, excluding capital costs and equipment maintenance.

Under the base assumptions, the two targeted scenarios reduced electricity consumption and negative impacts, such as global warming, with the third scenario generally achieving the lowest treatment burden.

The full-panel solar panel recycling process maintained significant benefits across many material-related impact categories, as it enabled the recovery of larger quantities of materials. The preferred chemical pathway varied depending on the specific impact category.

Operating margins were positive in all scenarios, and silver dominated the revenue from recovered materials despite its low mass.

The researchers cautioned that the targeted scenarios rely on electrostatic separation efficiencies and material values derived from published studies, which have not been experimentally validated for the material flows under investigation.

They clarified that a decline in electrostatic extraction performance or substitution could negate the process’s advantages in certain impact categories, as reviewed by the specialized Energy Platform.

The researchers noted that the results highlight the trade-offs between reducing treatment intensity and maintaining high levels of material recovery and value.

Design changes

Researchers note that frameless design is a distinct design option from flexible polyolefin encapsulation and glass engineering, and frameless solar panels are expected to maintain a market share of approximately 5% over the next decade.

In this context, removing the frame eliminates the frame disassembly step in the recycling process. However, aluminum frames are relatively easy to extract and contribute significantly to the revenue from recycling conventional solar panels.

Glass-on-glass designs, in turn, eliminate the rear plastic layer and increase the quantity and value of recoverable glass.

This study builds on the group’s previous work regarding the delamination of flexible polyolefin materials and the hybrid mechanical recycling of double-glass solar panels encapsulated with flexible polyolefin. Lithuanian manufacturer Soli Tek provided the materials necessary for the research.

The findings were published in a paper titled “Life Cycle Impact and Economic Evaluation of Frameless Recycling Strategies for Double-Glass Solar Panels Encapsulated with Flexible Polyolefin.”

This paper was recently published in the journal Solar Energy Materials and Solar Cells.

Researchers from the University of New South Wales, the Gdansk University of Technology, and the Polish Academy of Sciences found that silver can account for up to 47% of the recoverable value of a solar panel. However, the declining silver content in modern solar panels is expected to reduce recycling revenues in the future.

In a separate study, researchers from the Spanish Public University of Navarre and the National Renewable Energy Institute compared the separation process for ethylene-vinyl acetate (EVA) and flexible polyolefin (FPO) encapsulant layers, as well as thermoplastic polyolefin (TPO) layers.

The researchers found that both EVA and FPO require similar forces when heated beyond their melting range.