Experimental Methodology for the Separation Materials in the Recycling Process of Silicon Photovoltaic Panels

Abstract

As the use of photovoltaic installations becomes extensive, it is necessary to look for recycling processes that mitigate the environmental impact of damaged or end-of-life photovoltaic panels. There is no single path for recycling silicon panels, some works focus on recovering the reusable silicon wafers, others recover the silicon and metals contained in the panel. In the last few years, silicon solar cells are thinner, and it becomes more difficult to separate them from the glass, so the trend is towards the recovery of silicon. In this paper, we investigate the experimental conditions to delaminate and recovery silicon in the recycling process, using a combination of mechanical, thermal, and chemical methods. The conditions of thermal treatment to remove the ethylene-vinyl acetate (EVA) layer were optimized to 30 min at 650 °C in the furnace. To separate silicon and metals, the composition of HF/HNO3 solution and the immersion time were adjusted considering environmental aspects and cost. Under the selected conditions, panels from different manufacturers were tested, obtaining similar yields of recovered silicon but differences in the metal concentrations.

End-of-Life Photovoltaic Modules

“…These tiny fragments cause the embedded EVA film to lose its adhesiveness. It also negates EVA's influence on metal leaching [52], thus paving the way for the fragments to be directly soaked in an acid leaching reagent consisting of nitric acid, sulfuric acid, and hydrogen peroxide at 60 • C. Glass will not be dissolved during this process and can be recovered directly [53]. In contrast, valuable metals are recovered with hydrometallurgical techniques [54].…”

Delamination Techniques of Waste Solar Panels: A Review

“…The elimination of EVA was achieved through a heating process at a temperature of 650 • C for a duration of 30 min within a furnace. Subsequently, a solution of hydrofluoric acid (HF) and nitric acid (HNO 3 ) was employed to facilitate the separation of silicon and metals [35].…”

Review on Separation Processes of End-of-Life Silicon Photovoltaic Modules

“…If the frame, junction box, and cable are removed from the module and the module is immediately subjected to thermal treatment, harmful gases, such as HF, may be generated because the backsheet contains fluorine. Thus, the backsheet is often removed before thermal treatment, and the process is subsequently performed [17,18,22,29,[34][35][36][37][38][39][40][41].…”

“…These broken-down components are subsequently sorted and processed for recycling or reuse [22][23][24][25][26][27][28][29][30][31][32][33]; (2) Thermal processes utilize high-temperature processes, such as combustion, pyrolysis, and electro-thermal heating, to recover valuable materials from the PV modules. However, these processes require specialized equipment and expertise to ensure the safe and effective recovery of materials [17,18,22,29,[34][35][36][37][38][39][40][41];…”