Engineers at the University of New South Wales (UNSW) have developed a new, more efficient method of recycling end-of-life solar panels. The technology makes it possible to separate them quickly and efficiently from 99% of the materials of solar cell components.
The patented process involves using stainless steel balls as an abrasion-resistant screening aid, and the UNSW team said that in tests they have been able to separate 99% of the components, including silver, from the solar cell for potential reuse.
Thorough recycling of old solar panels remains a challenge because individual materials such as glass, silicon, precious metals, wires and plastic are integrated in such a way that they are difficult to separate. For the process to be viable, the components must be carefully separated to avoid contamination, but this has been difficult to achieve.
But now the Process Modeling and Optimization Laboratory at UNSW’s ProMO lab, led by Professor Yansong Shen, has developed a new process that allows them to sort individual materials quickly and efficiently. The process integrates conventional methods of separating large components such as the aluminum frame and glass sheets and crushing the cell, but relies on a highly abrasive separation system to improve the process.
“The key to our new process is the addition of screening aids that help break down the solar cells into smaller particles, allowing for better separation of all the components,” Shen said. “This makes it much easier to recover important elements, such as the silver in solar cells.”
The ProMO research group found that using stainless steel balls as a screening aid offered an optimal solution for the process.
“We spent about three or four months working on this element and also tested with screening aids made of clay or plastic,” team member Chengsun He said. “We can use screening aids of different sizes at different stages of the process. The main goal is to ensure that all the particles in the solar cells are crushed by screening aids, while the glass and other significant material remains intact from above.
The entire crushing and screening process, which takes place inside the vibrating tank, takes about 5-15 minutes to effectively separate 99% of the materials.
Once the material is separated using a new proprietary process, the team is able to utilize traditional chemical leaching as well as by precipitating special elements such as pure silica and silver, which make up about 0.05% of the panel’s total weight but make up about 14% of the material’s value.
Shen said the team is already working with some industry partners, “but we would like to do more industry collaboration to expand the process and improve the economic feasibility of the PV recycling process… Our group of 30 researchers is Australia’s largest in developing solar PV recycling technology, not just life cycle assessment, and probably one of the largest in the world. This patent is just one part of one recycling process for end-of-life solar panels, and we are also developing other solutions for other stages.
The International Renewable Energy Agency (IRENA) says that the cumulative amount of photovoltaic waste on a global scale will reach up to 8 million tons by 2030. This number will increase to 78 million tons of waste by 2050, when successive generations of solar panels installed at the beginning of the century reach the end of their useful lives, according to IRENA.