Electrolytic Silver Recovery from Photovoltaic Waste

Abstract

Listen

Translate article

As an increasing number of photovoltaic (PV) systems reach end of life, there is a growing need to develop a process to keep critical materials in the supply chain. Currently, the processing cost of recycling solar panels exceeds the value of raw materials being collected. While there are many ways to approach this problem, one standout method is to improve silver recovery efforts. Silver, which is used as the fingers on the front contact, makes up less than 1% of the total mass of decommissioned systems while constituting approximately 40% of the value of the raw materials. Mechanical separation techniques have been generally successful in extracting the silver, but the product is still low in concentration and recyclers encounter significant processing fees from off takers. In this talk, a chemical leaching process in conjunction with an electrochemical recovery system will be discussed as a means of extracting high purity silver from recycled PV materials. Classically, electroplating processes utilize solutions containing metals at concentrations >10 g/L. In this case, the expected concentrations are less than 2 g/L, and maintaining high yields will require the electrochemical device to operate at concentrations on the order of 100s of ppm. Mass transport limitations will be mitigated by the development of a flow-through 3D cathode architecture, which will allow the system to operate at lower concentrations without requiring the application of higher cell potentials that would decrease selectivity and subsequently lower the purity of the recovered silver product. The performance of these devices will be explored in conjunction with auxiliary system components and controls that will be integrated to yield an automated system for silver powder recovery. Figure 1