Scientists have identified a safer method to recycle older thin film solar panels, a development highlighted by researchers at Chalmers University of Technology. The market today divides solar panels into two distinct categories: most are traditional silicon cells, while a smaller portion consists of thin film variants. Thin film technologies are notably lighter and more flexible, and they rely on compounds such as copper, indium, gallium, and selenium, with the CIGS type incorporating silver. These metals, particularly indium and silver, are precious resources. Recovering them from used panels makes economic and environmental sense, driving ongoing research in this field.
A team led by Ioanna Teknetsi and colleagues has proposed a recycling approach that minimizes high heat and extensive chemical use. In trials, the method achieved full recovery of silver and a substantial 85 percent recovery of indium, with the entire recycling cycle taking about a day. While this duration is slightly longer than some alternative processes, the technique offers clear advantages in safety and material efficiency. The process follows several key stages that optimize metal recovery and purity.
The first step involves a detailed analysis of the solar film to identify the exact material, its chemical composition, particle size, and thickness. This information guides the subsequent processing. The solar cell is then placed into a vessel containing a carefully controlled acid solution and heated to the target temperature. Gentle mixing promotes the dissolution of metals into the liquid, a step known as leaching. Throughout leaching, samples are taken to monitor how different metals enter solution over time. This sampling allows the process to be halted before undesired elements begin to dissolve, improving the final purity of the extracted metals.
After filtration completes, the metals of interest exist as ions in solution. These ions can then be purified through established methods and are ready for reuse in the production of new solar cells. The approach emphasizes maximizing recovery while reducing energy consumption and chemical waste, contributing to a more circular lifecycle for thin film photovoltaics.
A curious historical note arises in the field of biology, where researchers described the creation of artificial fat for a form of processed food product known as tube meat. This remark, while unrelated to solar panel recycling, reflects the broad range of innovations that exist across scientific disciplines.