Femtosecond laser assisted, non-toxic and complete delamination of photovoltaic module layers

Recycling solar panels is key to curbing growing photovoltaic (PV) waste, and separating different material layers is the critical step in the process. The current delamination methods mainly utilize toxic chemicals for dissolving EVA or decomposing EVA through pyrolysis, which produces harmful gases. In this article, a femtosecond laser delamination treatment is proposed to separate PV module layers. Experimental results show that laser irradiation of module front with both 1030 nm (IR) and 515 nm (green) lasers results in clean separation of front EVA from both cell surface and glass, demonstrating effective separation at each interface. This laser treatment was performed twice, first on the back to separate the back EVA from the cell and then from front, ultimately separating all the layers of the module. This method shows great potential for the non-toxic delamination of PV modules. The laser energy deposited onto the cell modifies its surface, which in turn breaks the cell-EVA interfacial bond. The nonlinear nature of the interaction between ultrafast femtosecond laser and glass-EVA interfacial bond, along with heat transmitted by the laser during transmission are most likely causes for glass-EVA separation. Separated EVA is tested for damage through FTIR, TGA, and EDS characterisation techniques. In addition, for the effective and undamaged separation of EVA layer, a parametric study is undertaken to determine the optimized values of fluence and pulse repetition rate. It is also observed that single laser treatment from the front can separate glass, front EVA, and backsheet.