Solar panels with discarded ‘black gold’ from wafer production

An international consortium led by Norwegian research institute Sintef is trying to reuse silicon powder, which is normally regarded as waste, in ingot and wafer manufacturing for different industrial high-end applications, including solar panel production.

The group is working under the umbrella of the EU-funded Icarus project, which aims to develop modular processing solutions to recover 95% of high-value raw materials from silicon ingot and wafer production via fluidized bed (FBR) reactors based on the so-called Siemens process.

“It’s possible to recover this material as part of the production process,” said researcher Martin Bellmann. “And maybe this will enable us to establish a new solar-based industry in Europe.”

Bellmann described the discarded sawdust silicon powder as “black gold” and said that around 35% of the silicon in ingot and wafer manufacturing is lost after the sawing process. This powder can be stored in a liquid sludge mixture with contaminants from the sawing process such as oxygen, carbon, nickel, iron, and aluminum.

“Silicon contaminated by these metals is not good for solar panel manufacture,” Bellmann said, noting that the consortium is currently identifying ways to decontaminate the material. “A number of partners are testing different ways of separating silicon from the contaminated mixture.”

The consortium also wants to reuse the quartz crucibles that are used to smelt silicon for silicon carbide production.

“Normally, we use so-called high-purity quartz to make silicon carbide, but this is very expensive,” Bellmann said. “Our idea is that it might be possible to replace high-purity quartz with crucible waste, which is also in essence quartz of very high purity”

The consortium includes Norway’s Northern Silicon AS, French PV recycling specialist Rosi Solar, Italy’s Magneti Marelli Spa, and Germany’s bifa Umweltinstitut GmbH.