Nuvosil recycles silicon from solar cell production

Solar power plays an essential part in the global transition to renewable energy.

Silicon wafers – the thin semiconductors used in solar panels– are made by slicing large silicon blocks. During the cutting process, 40 per cent of the original material is lost as fine silicon powder. This powder is either disposed of in landfills or recycled in a costly, energy-intensive remelting process, which often yields a low-quality product.

Reducing waste of high-grade silicon – an energy-intensive material in itself – can help to shrink the environmental footprint of solar cell manufacturing and move the industry towards a circular production model.

Nuvosil’s Low Energy Recycling (LER) is an efficient method of recycling surplus silicon materials from solar wafer manufacturing, resulting in a high-quality material.

Based on aluminium recycling technology developed by Hydro and the Norwegian University of Science and Technology (NTNU), Hydro and Nuvosil have created a screw extruder that can process and recycle silicon powder and other metal materials using minimal heat and energy.

Nuvosil’s end-product is the Low Energy Master Alloy (LEMA) for use in high-value applications such as aluminium manufacturing, where it replaces conventional metallurgical silicon (MG-Si). LEMA consists of 70 per cent silicon and 30 per cent aluminium materials.

In addition to partners Nuvosil AS and Norsk Hydro ASA, LER development efforts are supported by a team of industrial and R&D partners: German thermoplastic manufacturer Reifenhauser GmbH, Austrian wet grinding technology specialist CEMTEC GmbH, SINTEFand NTNU.

The Low Energy Recycling process is significantly more efficient than existing recycling methods for silicon powder. It requires up to 90 per cent less energy and saves between 40 and 50 per cent in costs compared to conventional remelting.

Moreover, by utilising what is often disposed of as waste and creating a high-value material, the process promotes higher recycling rates and circular focus in the solar cell industry.

The market for solar cells has grown rapidly over the past decade, and is expected to maintain an annual growth rate of between 10 to 15 per cent for the foreseeable future, according to the IEA.

Against this background, Nuvosil estimates the total market potential for the Low Energy Master Alloy at 180 000 metric tons in 2022, growing to roughly 240 000 metric tons in 2025.

The screw extruder process has been tested and verified in small-scale applications. An industrial-scale prototype will be ready for testing in August 2021. The company aims to have the solution tested and qualified by December 2021 and plan to start commercial operations in early autumn 2022.