Recycling end-of-life solar panels: A comparative study of thermal and solvent delamination techniques

Abstract

The rapid expansion of photovoltaic (PV) energy has led to a growing concern regarding the management of endof-life solar panels. Projections indicate a substantial growth of PV panel waste in the coming years, highlighting the urgent need for effective disposal solutions. In this study, the most critical phase in the recycling of Si-based PV panels, i.e., module delamination, was investigated under two scenarios: solvent- and thermal-based methods. The study encompasses the complete recycling chain, from initial module disassembly to its delamination and the comprehensive characterization of the resulting material fractions. Neuro-fuzzy models were developed to maximize the efficiency of the delamination process. An innovative simulated distillation with an equivalence to a 100 theoretical-plate physical distillation procedure was also designed to identify potential valorizable hydrocarbons. The most effective solvent-based delamination process was achieved with toluene for 180 min assisted by ultrasounds, reaching a separation degree of 0.75 (complete glass and backsheet detachment, but with polymer residues on the Si cell surface). Thermal delamination proved significantly more effective, achieving complete separation (degree = 1) with full encapsulant removal, recovery of silicon cells without microcracks, and isolation of high-purity metallic filaments, under a range of conditions (350–550 ◦C, 30–50 min, 21 % O2). Finally, simulated distillation confirmed the presence of valorizable hydrocarbons with the following product distribution: 65 % light naphtha, 17 % heavy naphtha, 16 % kerosene, and 2 % gas oil (dieselrange).