A Unique Two‐Step Process Combining Acid and Alkaline Etching for Recovering High‐Purity Silicon from Waste Crystalline Silicon Solar Panels

Effective resource recovery and reuse are important to overcome the enormous challenges associated with waste photovoltaic (PV) module management and limited raw material supply, but these processes are severely hampered by the inefficient and unprofitable recovery of current technologies. This article presents a unique approach to recover high‐purity silicon from end‐of‐life (EoL) silicon solar panels through a two‐step process combining acid etching and alkaline etching, which does not involve the use of hydrofluoric acid (HF). Firstly, a preliminary delamination process is carried out on EoL PV modules using thermal treatment to recover Al frames, tempered glass, Cu tapes, and silicon wafers. Then, for the removal of impurity Ag, the better acidic process between HNO 3 and H 2 SO 4 is compared. Finally, by comparing different etching processes, it is found that NaOH can not only efficiently remove the impurity Al but also replace HF for removing antireflective coating. Therefore, a two‐step chemical process combining acid and alkaline immersion significantly reduces the main impurities Ag and Al. The process is greener and has less silicon loss than HF, eliminating potential human health and environmental issues associated with HF. In addition, the purity of silicon recovered by this process is up to 4N grade.