Researchers from Sweden's Chalmers University of Technology propose a 'kinder' and more environmentally friendly way, though longer, to recover 100% of silver and about 85% of indium from copper-indium-gallium-diselenide (CIGS) thin film solar cells using Midsummer's cells for the experiment.
For their research, the team used the process of leaching that entails placing the solar cell in a container with a desired volume of HNO3 solution of a specific concentration at the desired temperature, to facilitate the dissolution of metals with agitation.
On completion of this process, desired metals are in the solution in the form of ions that can be easily purified to be reused in the manufacture of new solar cells, says the team. It is conducted at room temperature without adding heat.
Before the process is initiated, the thin film panel is analyzed with regard to material, chemical composition, particle size and thickness. The team is able to assess the effectiveness and chemical reactions by analyzing samples taken at specific times during the process.
Since different metals are leached at different times, the process can be stopped before all the metals begin to dissolve, which in turn contributes to achieving higher purity.
Processes deployed until now use a large amount of heat and chemicals which is an expensive endeavor that's not good for the environment, according to the team.
Chalmers team claims their leaching process is a 'much kinder way' using less amount of chemicals. Even though the process takes one day to complete, it is more cost-effective and better for environment.
"This research suggests that recovery of valuable elements from CIGS material within 24 h is feasible without using harsh leaching conditions of elevated acid concentrations and temperatures and that related risks and costs can be reduced," reads the research work. "Further optimization of the method should be investigated to develop viable metal recovery process from CIGS solar cells."
The research work has been published in the journal Solar Energy Materials and Solar Cells under the title Valuable metal recycling from thin film CIGS solar cells by leaching under mild conditions.
TaiyangNews recently concluded our Solar and Sustainability Virtual Conference that discussed efforts into recycling of solar panels for a sustainable PV life cycle. Details of presentations and conference summary are available here.