Back EVA recycling from c-Si photovoltaic module without damaging solar cell via laser irradiation followed by mechanical peeling.

Abstract

Debonding of ethylene-vinyl acetate (EVA) copolymer is critical for recycling the end-of-life (EoL) crystalline silicon (c-Si) photovoltaic (PV) modules. The currently utilized methods are mainly based on EVA chemical dissolution or pyrolysis, which cannot recycle EVA and usually causes environmental problems. Here, a laser irradiation followed by mechanical peeling method was proposed to recycle the back EVA layer on the solar cell in the c-Si PV module. Specifically, after removing junction box, Aluminium (Al) frame and back-sheet from the c-Si module, a 1064nm optical-fiber pulsed laser was utilized to pass through the back EVA and irradiate onto the cell/EVA bonding interface. The rear Al and silver (Ag) electrodes of the solar cell would absorb the laser pulse energy to induce a temperature rise across the cell/EVA interface, which could weaken the adhesive strength of the back EVA. The dependence of the debonding effect on the power density (P) and pulse repetition rate (PRR) of the laser was investigated carefully. When the laser parameters were controlled appropriately, the back EVA layer could be mechanically peeled off easily from the solar cell, and at the same time, the peeled-off EVA and the solar cell were both undamaged by the laser treatment. The EVA recycling can reduce possible environmental pollution risk greatly. The undamaged c-Si solar cell also provides possibility to be recycled completely in subsequent processes. The recycled EVA and solar cell both have great potential for reuse. Furthermore, for PV module with defective back-sheet, the method also offers an available way to remove the EVA adhesive for replacing the back-sheet.