Resource efficient metal extraction and silicon wafer recovery from end-of-life monocrystalline solar cells: A chemical and environmental perspective

Abstract

With the rapid expansion of photovoltaic technology, managing photovoltaic-solid waste has become a growing challenge. This study presents an efficient process for recovering metals and silicon wafers from end-of-life solar cells, which has significant potential for generating auxiliary sources of revenue for the world economy and mitigating resource depletion risks along with environmental offsets. Following aluminium removal from the back of the solar cells utilizing hydrochloric acid, 99.997 % pure silver extraction was successfully done via chronoamperometric etching with an exceptionally low energy consumption of 0.012 kWh.kg⁻¹, ensuring 98.31 % extraction and 96.75 % recovery efficiency. The passivation layers were removed by hot ortho-phosphoric acid. The p-n junction etching was performed independently, yielding an average recovery of 94.46 % for alkaline etching (5 N purity) and 94.25 % for acidic etching (6 N purity). The environmental impacts of the developed recycling process were evaluated via life cycle assessment. Structural characteristics of reclaimed materials were studied using XRD, EDX and ICP-OES. A cost analysis validated the commercial viability of the process. Significant environmental offset of ∼ 230.80–251.68 kg CO₂ eq. for every 1.0 kg of end-of-life silicon solar cells can be achieved by reducing hazardous waste, reclaiming high-purity materials, and lowering energy demands, reinforcing the circular economy principles in PV recycling.