(663b) Using Laser Irradiation to Separate Polymer Adhesives from Silicon in End-of-Life PV Panels for Recycling Purpose

The active semiconductor component (Silicon) of a solar photovoltaic (PV) panel is encapsulated by an ethylvinylacetate (EVA) adhesive and protected with a top glass layer. The detachment of this glass-EVA layer from the silicon (Si) is a significant challenge in recycling end-of-life PV panels. To tackle this issue, a novel impulsive light-debonding technique was devised and tested on both model and commercial poly-crystalline PV panels. Nanosecond laser pulses can effectively induce transient melting at the EVA-Si interface, severing the adhesive bond. The debonding efficiency, influenced by laser pulse fluence (energy per area), wavelength, applied pressure, and scanning speed, was systematically evaluated. For model PV panels, the necessary single-pulse laser fluences for gravity-driven separation were found to be 0.2, 0.3, and 0.7 J/cm^2 at wavelengths of 355 nm, 532 nm, and 1064 nm, respectively. Shorter wavelengths concentrate heat near the silicon surface, minimizing the fluence required for debonding, whereas higher fluences offset increased scanning speeds. Post-irradiation analysis of the silicon surfaces, using optical and electron microscopy, revealed that the textured antireflection coating was eliminated, yet the silver metal grid remained unaffected. Initial tests with 532 nm laser pulses successfully detached the glass-EVA layer from sections of decommissioned commercial PV panels, despite extensive cracking in the top glass layer. The nanosecond laser debonding method provides a new method for disassembly of end-of-life solar panels that avoids the use of chemical solvents or heating, or mechanical grinding.