Scientists have proposed a safe way to recycle old thin-film solar panels. In this respect informs Chalmers University of Technology.
Solar panels on the market to date are divided into two unequal groups. 90% are conventional silicon solar cells and the other 10% are thin film. Thin-film batteries are flexible and lightweight and are based on a combination of copper, indium and gallium selenide, including one type (CIGS) silver. Indium and silver are precious metals and therefore it would be beneficial to recover them from used batteries.
Ioanna Teknetsi and her colleagues have proposed a way to recycle such batteries, eliminating the use of high temperatures and lots of chemicals. This method was able to recover 100% silver and 85% indium, and the entire cycle took a full day, which was slightly longer than using alternative technologies. The process itself proceeds as follows.
First, the solar cell film is analyzed to determine the material, chemical composition, particle size and thickness. The solar cell is placed in a container with acid solution at the desired temperature, mixed to facilitate the dissolution of metals in acid. This process is called leaching. The efficiency of filtration and reactions is then evaluated by analyzing samples as different metals are leached at different times. This means that the process can be stopped before unwanted metals start to dissolve, helping to achieve higher purity.
Finally, when filtration is complete, the desired metals are in solution as ions and can be easily purified for reuse in the production of new solar cells.
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