Recycling of waste crystalline silicon photovoltaic modules: Efficient decapsulation and silver extraction using environmental-friendly reagents and deep eutectic solvents

Abstract

The transformation of the global energy structure has driven the rapid development of the photovoltaic industry, inevitably leading to the generation of upgraded and end-of-life photovoltaic waste. Effective treatment of this waste is crucial for environmental protection and advancing the circular economy. Crystalline silicon photovoltaic modules, which dominate the market, contain high-value recyclable materials such as plate glass and silver. Decapsulation, the critical first step in recycling, enables the separation of layered panel materials. This study employs environmental-friendly isopropyl myristate and diethyl malonate for decapsulation, achieving optimal processing within 60 min. These reagents retained high purity and generated minimal byproducts even after 40 reuse cycles, demonstrating excellent reusability. The characteristic functional group peaks of the ethylene vinyl acetate encapsulant remained unchanged, with only variations in peak intensity. The disruption and reorganization of its cross-linked structure weakened its adhesion to other panel layers. These reagents exhibited limited leaching effects on Ag from solar cells, facilitating subsequent Ag recovery. A stable deep eutectic solvents synthesized from FeCl₃·6H₂O and urea demonstrated low melting points of approximately −25.98 °C (molar ratio 1:1) and −54.09 °C (molar ratio 1:3). This deep eutectic solvents efficiently enriched Ag from delaminated solar cells, achieving a 93.55 % Ag extraction rate (20 min, 80 °C, 400 rpm). This study combines the wet decapsulation of photovoltaic modules with the Ag extraction of solar cells. The eco-friendly reagents adopted provide new guidance for the recycling of waste photovoltaic modules.