Researchers have evaluated the environmental and economic performance of recycling strategies specifically designed for frameless glass-glass photovoltaic modules encapsulated with polyolefin elastomer (POE). This module design is increasingly prevalent in bifacial applications, yet most existing recycling studies have focused on conventional modules featuring ethylene-vinyl acetate (EVA) encapsulants, plastic backsheets, and aluminum frames. The international research team compared three distinct scenarios for processing a single 27 kg module: thermal and chemical treatment of the entire module; mechanical treatment with selective processing limiting thermal steps to specific fractions; and a third scenario adding further fractionation via electrostatic corona separation after thermal treatment.
Each recycling scenario was assessed using two chemical routes for metal recovery: sodium hydroxide followed by ammonia and hydrogen peroxide, or nitric acid combined with hydrogen peroxide. Described as an early-stage comparative study based on prior laboratory results, the analysis employed a gate-to-gate life cycle assessment using ReCiPe 2016 midpoint indicators with credits for avoided primary materials. The economic evaluation calculated a process-level operational margin based on revenue from recovered materials and selected operating costs, excluding capital expenditures and equipment maintenance.
Under baseline assumptions, the two targeted recycling scenarios demonstrated reduced energy demand and improved outcomes regarding global warming impacts, with the third scenario generally achieving the lowest processing burden. However, whole-module treatment retained stronger benefits in several material-driven impact categories due to higher material recovery rates used for credits. The preferred chemical route varied depending on the specific impact category analyzed. While the operational margin remained positive across all cases, silver dominated the revenue from recovered materials despite its very low mass within the module.
The researchers cautioned that the advantages of targeted scenarios rely heavily on electrostatic separation efficiencies and material values drawn from literature that were not experimentally validated for these specific material streams. Lower recovery rates or substitution performance could eliminate the environmental benefits in certain impact categories. The study highlights the inherent trade-offs between reducing treatment intensity and maintaining sufficiently high material recovery and value. Design changes such as frameless construction eliminate the de-framing step but remove aluminum, which is relatively easy to recover and contributes substantially to revenue in conventional modules. Conversely, glass-glass designs eliminate plastic backsheets and increase the volume of recoverable glass.
The findings, published in Solar Energy Materials and Solar Cells by Aistis Rapolas Zubas, Jolita Kruopienė, Gintaras Denafas, Floriana La Marca, and Alessandra Bonoli, build on earlier work regarding POE delamination and mechanically driven hybrid recycling. Material for the research was provided by Lithuanian manufacturer Soli Tek. The study notes that frameless modules are expected to maintain a market share of approximately 5% over the coming decade. Additionally, researchers from the University of New South Wales, Gdansk University of Technology, and the Polish Academy of Sciences found that silver can account for up to 47% of a module's recoverable value, although falling silver content in newer panels may reduce future recycling revenue.
Sources: pv magazine.