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Image credit: Fraunhofer ISE

Clean Power

Recycling News: Fraunhofer ISE Invents Process For Solar Panels

Fraunhofer ISE has developed a process for recycling the silicon in old solar panels.

The big knock on new technology like electric cars and solar panels is that they are not recyclable. People haven’t cared a flying fig leaf about recycling stuff for the past 100 years. If they did, citizens would be at the gates of the corporate headquarters of Nestlé, Coca Cola, and Pepsi with flaming torches and pitchforks demanding they stop inundating the Earth with their endless profusion of waste products.

But suddenly, people are all atwitter about what will happen to the batteries of electric cars. Fearmongers on the internet are telling people they will have to drive their old electric cars into lakes and rivers when they stop working. The amazing thing is, people believe that codswallop and repeat it to their friends as if it were carved on the stone tablets Moses brought down with him when he descended the mountain. So much for public education making people smarter.

Another cry you hear from the anti-technology crowd is that millions of old solar panels will be dumped into landfills to fester for centuries. Horse-puckey! Do we need a way to recycle solar panels? Yes, we do. And are responsible adults working on such systems as we speak? Yes, they are. Calm down, people. Everything you read on Twitter or Facebook is not gospel. And let’s not get started on the deliberate misinformation spewed by the talking heads on Faux News 24 hours a day.

Frauhnofer ISE is one of Germany’s premier research institutions. In a press release this week, it says it has devised a way to recapture the silicon in old solar panels and reprocess it so it can be reused in the manufacture of new solar cells. It says about 10,000 tons of silicon in discarded photovoltaic modules end up on the recycling market each year in Germany. That figure will rise to several hundred thousand tons per year by 2029.

Currently, the aluminum, glass, and copper of the discarded modules are reprocessed, however, the silicon solar cells are not. Frauhnofer’s researchers have developed a way to reprocess the silicon in the discarded modules on an industrial scale and reuse it to make new PERC solar cells. Silicon is the main component of solar cells.

Older Solar Panels Date To 2009

Most PV systems in Germany were installed between 2009 and 2011 during the first wave of photovoltaic expansion. “This expansion will foreseeably be followed by a first wave of disposal twenty years later, around 2029, when the feed-in tariff for the installed PV modules expires,” explains Prof. Dr. Andreas Bett, director of Fraunhofer ISE. “Therefore, it is necessary to establish adequate processes and procedures for recovering the silicon material from the discarded modules at an early stage.” As of the end of 2021, there were about 5 million tons of solar panels installed across Germany, with a silicon content of 150,000 tons.

With the new process, it is possible to recycle all crystalline silicon PV modules, regardless of manufacturer and origin. Dr. Peter Dold, project manager at Fraunhofer CSP, explains: “If this were not the case, then this would be far too much work for the recycling companies. It was important for us to develop a scalable process that makes economic sense. A lot is possible in the lab, but our new process should prove itself in the practice for the recycling industry.”

Solar cell fragments are separated and collected from byproducts of the mechanical recycling process. The cell fragments range in size from 0.1 to 1 millimeter, and are first freed from the glass and plastic they are attached to by various sorting processes. Then the silver contacts on the back of the silicon are removed along with the anti-reflective layer, and finally the emitter, via wet chemical etching. Once cleaned, the silicon is processed into monocrystalline or quasi-monocrystalline ingots and then into wafers.

The crystallization is carried out with 100% recycled silicon without the addition of commercial ultra-pure silicon. In the first trial, the solar cell conversion efficiency was 19.7%. “This is below the efficiency of today’s premium PERC solar cells, which have an efficiency of around 22.2 percent, but it is certainly above that of the solar cells in the old, discarded modules,” says Dold.

What This Means for Recycling

There are reports the materials recovered during lithium-ion recycling perform as well or better than new materials. That is not yet true of the recycled silicon from the Fruanhofer process, but this is a new technique. No doubt further refinements in the system will boost the performance of the recycled silicon. Most early solar panels will be reaching the end of their useful life in about 7 years. When that time comes, Fraunhoufer ISE will have the tools to make sure they are recycled properly, which is great news for the renewable energy revolution and the quest for a sustainable environment.

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Steve writes about the interface between technology and sustainability from his homes in Florida and Connecticut or anywhere else the Singularity may lead him. You can follow him on Twitter but not on any social media platforms run by evil overlords like Facebook.


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