Removal of encapsulant ethylene-vinyl acetate for recycling of photovoltaic modules: Hansen solubility parameters analysis

Delamination of photovoltaic modules is crucial for the recovery of solar cell materials. In this article, we investigate the swelling of ethylene-vinyl acetate (EVA) using various organic solvents at a temperature range between 25 and 55°C. The swelling of the encapsulant EVA caused by the interaction of organic solvents aids in the separation of glass, solar cell, and Tedlar layer in the recycling of photovoltaic modules. Further, we quantify the interactions between the encapsulant EVA and the organic solvents by the solvent weight ratio and solvent volume ratio of EVA. The quantification of interactions between encapsulant EVA and various organic solvents is used to estimate the Hansen solubility parameters of encapsulant EVA. The temperature-dependent variation of physical properties of organic solvents and their effect on encapsulant EVA swelling are described. Organic solvents retained in encapsulant EVA matrix after drying at room temperature can be viewed as a method to reduce emissions of volatile organic compounds during recycling. Additionally, our experiments suggest that d-limonene, xylene, and toluene are the most effective solvents for delamination of end-of-life photovoltaic modules for recycling.