Thermal Decomposition Behaviour of Ethylene-Vinyl Acetate from End-of-Life Monocrystalline Solar Panels Under Slow Pyrolysis Treatment

Abstract

This study investigated the low-temperature thermal treatment of EVA encapsulant from an end-of-life 180 Wp monocrystalline PV panel while evaluating the preservation of recovered crystalline silicon. TGA showed that EVA underwent major decomposition between approximately 330 and 480 °C, with an onset temperature of 310.4 °C and mass loss of 94.34%. Thermal treatment was subsequently conducted at 300–500 °C for 30–50 min under nitrogen using a Taguchi L9 design. XRD analysis showed substantially improved silicon diffraction intensity after treatment, while the 300 °C residues were unsuitable for analysis due to incomplete EVA decomposition. Taguchi-based analysis was used as a preliminary screening approach to compare the investigated treatment conditions. Within the experimental range, 400 °C for 40 min was identified as a practical treatment condition based on the measured XRD response, treatment duration, and estimated furnace energy requirement. The results indicate that controlled thermal treatment promoted substantial EVA decomposition while maintaining detectable crystalline silicon in the treated material.