Swiss solar furnaces turn watch scrap into steel

October 06, 2025

A pioneering Swiss enterprise has achieved a global milestone by launching the world’s first solar-powered furnaces capable of melting and recycling industrial steel waste using nothing but renewable solar energy.

Based in Jura, Panatere—a trailblazer in sustainable metallurgy and circular manufacturing—unveiled the two cutting-edge installations on October 3 in La Chaux-de-Fonds, the heart of Switzerland’s historic watchmaking region.

Revolutionizing steel recycling in watchmaking and medical industries

The two pilot furnaces are designed to recycle premium stainless-steel offcuts from local watchmakers and medical device manufacturers, both renowned for their precision engineering and heavy reliance on high-quality alloys.

This forward-looking project is supported by Haute École Arc Ingénierie and the University of Franche-Comté through the Interreg France–Switzerland program. “This moment has been ten years in the making,” said Raphael Broye, CEO of Panatere, during the inauguration ceremony.

Harnessing the power of the sun to melt metal

The revolutionary solar furnace technology utilizes concentrated sunlight to achieve temperatures up to 2,642°F (1,450°C)—enough to melt stainless steel without fossil fuels.

The larger prototype features a 1,485-square-foot (138 m²) heliostat made of 40 movable mirrors that follow the sun’s path and reflect its rays toward a 32-foot (10 m) concave dish concentrator.
Meanwhile, the smaller unit includes a 323-square-foot (30 m²) heliostat and a 129-square-foot (12 m²) concentrator composed of around 460 mirrors.

Both systems channel the concentrated light into a solar reactor, where the metal scraps are melted and cast into recycled steel ingots. According to Loïc Bonsack, innovation and industrialization project manager at Panatere, the newer compact design can intensify sunlight up to 5,500 times, reaching 2,000°C (3,632°F) inside the crucible.

The performance figures were validated through simulations conducted by researchers from the Université de Franche-Comté and Haute École Arc Ingénierie (HE-Arc), as part of the Interreg France–Switzerland Rasol program.

Toward a carbon-neutral future in steel production

Panatere plans to continue collaborating with local partners to refine the solar recycling process and expects to open a full-scale solar steel plant by 2028, either in La Chaux-de-Fonds or in the Wallis mountains of southwestern Switzerland.

Once operational, the facility aims to produce up to 1,000 tons of solar-recycled steel annually, completely powered by sunlight. The innovation is projected to drastically cut CO₂ emissions and promote circular manufacturing practices in Switzerland’s high-end industrial sectors.

“Our role also includes verifying the composition of recycled steel alloys to maintain exceptional quality,” explained Raymond Constantin, a materials characterization expert involved in the project.

Currently, producing one kilogram (2.2 lbs) of recycled steel using conventional methods emits about 6.8 kilograms (15 lbs) of CO₂. In comparison, Panatere’s solar process could reduce emissions to just 41 grams (0.1 lbs) per kilogram—over 165 times lower than traditional recycling.

“There is now a viable economic model for sustainable metallurgy,” said Broye, emphasizing that the approach reinforces local supply chains and Swiss manufacturing prestige. “With rising metal prices and limited resources, we can make this process both environmentally and economically sustainable, even with Swiss labor costs.”