Among the protagonists of the project that aims to reduce the EU’s dependence on critical raw materials for the production of solar panels are ETA Florence and the Norwegian University of Science and Technology (NTNU). PV magazine Italia interviewed the two researchers Maria Wallin and Katarina Jakovljevic (Original article here).

Reducing Europe’s dependence on critical raw materials, particularly silicon essential for solar panel production, is the objective of Resilex, a project funded by the European Union involving numerous partners, including the Norwegian University of Science and Technology (NTNU) and the Italian company ETA from Florence.

To delve deeper into the contents and innovations of Resilex, we interviewed Maria Wallin and Katarina Jakovljevic, researchers from NTNU’s Department of Materials Science and Engineering, who provided us with a technical overview of the project.

Closing the Silicon Loop

“The main goal is to reduce the EU’s dependence on critical raw materials for solar panel production,” explain the two researchers. “To improve the resilience and sustainability of the critical raw materials value chain in Europe, Resilex aims to strengthen every part of the silicon value chain through the technological improvement of all its processes.”

A key element is the recycling of photovoltaic panels and Si-kerf, which is the sawdust generated during silicon processing, to obtain high-purity silicon again. “The silicon produced is evaluated for both photovoltaic and battery applications.”

From Lab to Industrial Scale

The project has evolved significantly over time: “At NTNU, high-purity silicon obtained with our process was optimized at laboratory scale (gram scale) before producing the material at pilot scale (100 kg scale) and finally refining the material to obtain a silicon ingot with a purity of 99.999% using the Czochralski growth method.”

This is a result that is now ready for industrial use. “Resilex is approaching its final year, so the focus has shifted from small-scale pilot projects to large-scale ones, and now the focus is on developing solid business cases and environmental models (LCA) for the developed processes.”

The Challenges of Recycling

Recycling silicon is not simple. The biggest difficulty? “Developing a greener method to recycle photovoltaic waste and turn it into new photovoltaic products with the same functionality as those on the market.”

In this sense, NTNU has developed the patented SisAl process, which allows for the efficient recycling of Si-kerf: “NTNU’s main objective in Resilex is the recycling of Si-kerf and obtaining High-purity Silicon (HP-Si) through different refining stages. The HP-Si is then sent to the French partner CEA for the production of a purer ingot and, subsequently, photovoltaic cells.”

Towards a circular silicon economy, the potential economic and environmental impacts are significant: “Better utilization of raw materials means less extraction of raw materials, therefore a smaller quantity of raw materials to be processed subsequently.”

Meanwhile, the regulatory context is pushing in this direction: “The Critical Raw Materials Act (EU Green Deal, etc.) provides a favorable framework for the reuse and recycling of silicon.”

Italy and the European Horizon

And in Italy? The potential is there, but new synergies are needed: “To implement the project in Italy or other countries, new circular business models need to be established between scrap collectors, including photovoltaic and aluminum recyclers, and the silicon and steel industry.”

According to the researchers, “it would be beneficial to build strong relationships with potential end-users of the produced HP-Si, photovoltaic and battery manufacturers. For Europe to become more independent from other continents, the possibility of bringing photovoltaic production back to Europe should be considered to ensure control over the entire value chain.”

Wallin and Jakovljevic conclude: “It is hoped that Resilex will contribute to increasing the photovoltaic recycling rate and that profitable products will be obtained from the process. If we succeed in creating a Resilex plant in Europe, we will be less dependent on other countries, such as China.”