Recovery of complete crystalline silicon cells from waste crystalline silicon photovoltaic modules

The paper reports a new process to efficiently recover intact crystalline silicon cells from waste crystalline silicon photovoltaic (PV) modules. Firstly, the EVA adhesive film is dissolved with preheating treatment and ultrasonic-assisted toluene, and the backsheet are peeled off. The EVA film is then removed by thermal degradation. Finally, the high value but low reactivity silver (Ag) and aluminum (Al) are leached out with nitric acid (HNO3). The hydrochloric acid (HCl) precipitation-ammonia (NH3·H2O) solubilization-hydrazine hydrate reduction process route was used to recover Ag. Addition of NH3·H2O to a leach solution containing only Al produces an aluminum hydroxide (Al(OH)3) precipitate, which is then heat treated to produce aluminum trioxide (Al2O3). After the above process method, the recovery rate of complete crystalline silicon cells reaches more than 50%, the recovery rate of Ag reaches 95%, and the recovery rate of Al reaches 91%. The most important feature of this study is that the recovered intact crystalline silicon cells can be directly used in the reproduction of crystalline silicon PV module components, which greatly reduces the production cost and improves the efficiency of resource utilization.Implications statement In this study “Recovery of complete crystalline silicon cells from waste crystalline silicon photovoltaic modules,” a new process combining organic solvent method and thermal treatment method is provided with the main objective of efficient recovery of intact crystalline silicon cells. Pre-heating treatment and ultrasonic-assisted toluene dissolution of EVA adhesive film are used to strip the fluorine-containing backsheets, which are centrally processed and reused to achieve environmental protection and resource reuse. The EVA film is then thermally degraded to obtain a complete crystalline silicon cell. Finally, Ag and Al were efficiently recovered from crystalline silicon cells by chemical methods. The optimized process has the advantages of high integrity rate of recycled crystalline silicon cells, low recycling cost and low environmental pollution.