Recycling of silicon solar panels through a salt-etching approach

The production and use of silicon (Si) solar panels is soaring during the transition to a carbon-neutral energy system. To mitigate their environmental footprints, there is an urgent need to develop an efficient recycling method to handle end-of-life Si solar panels. Here we report a simple salt-etching approach to recycle Ag and Si from end-of-life Si solar panels without using toxic mineral acids and generating secondary pollution. The etching process is enabled by the high corrosivity of molten hydroxide that spontaneously reacts with SiNx, SiO2, Al2O3 and Al at the surface of Si wafers through the top-down direction, thereby directly separating Ag from Si wafers. The etching process takes only 180 s to recover >99.0% of Ag and >98.0% of Si from end-of-life Si solar panels. In addition, Cu, Pb, Sn and Al in Si solar panels are also recovered through a combined oxidation, alkaline leaching and electrodeposition approach. Overall, this study presents a viable approach for sustainable management of end-of-life Si solar panels, paving the way to a circular economy. The booming production of silicon solar panels, a core technology in the energy transition, calls for proper end-of-life management. Here the authors propose a salt-etching approach that enables efficient recycling of critical materials from end-of-life silicon solar panels, without the use of toxic reagents.