This Group of Researchers Can Recover and Recycle Silicon from Solar Panels

Picture this - a society thriving in green infrastructure that offers zero-emissions energy and can recycle nearly anything with ease. Water shortages are no longer a problem, and transportation doesn't significantly contribute to climate change. It's just a way to get around.

This Group of Researchers Can Recover and Recycle Silicon from Solar Panels
By-products of the treatment process at Reiling GmbH, from which the solar cell fragments are separated and collected (left).
Purified silicon and wafers made from 100% recycled silicon (middle).
PERC solar cells made of 100 % recycled silicon with an efficiency of 19.7 percent (right).

Many businesses, organizations, and even some governments are working to make that vision a reality. With emerging technology aimed at sustainable development, that reality is getting closer and closer with each passing day, particularly in the realm of renewable energies.

Opportunities for Change

Renewable energy includes solar, geothermal, wind, biomass, and hydropower. These options carry varying degrees of nuance regarding environmental footprint, but have immense potential to shift society away from fossil fuels.

One star of the renewable energy sector is solar, which has grown substantially in popularity due to climate change awareness driving consumer demand, regulations, and decreasing prices.

Solar energy works via two methods: photovoltaic (PV) solar panels and concentrating solar-thermal power (CSP). The former is the more common, absorbing the sun's solar radiation via panels to create an electrical charge. The latter reflects the sun's solar radiation off a mirror-like panel to a receiver, which converts it to heat used to produce energy.

Solar energy has seen an impressive decrease in price, improving accessibility and allowing for increased installation around the globe. But there are still some challenges with this renewable.

Some examples include reliance on weather patterns, optimal storage choices, and end life disposal.

End-life disposal can drastically alter a given product's environmental footprint. For example, if solar panels were 100% recyclable, their overall environmental footprint would drop. On the flip side, if solar panels couldn't be recycled at all, they would end up in landfills and their footprint would rise.

Conducting a product life-cycle analysis from manufacturing to end-use is vital to determining whether a renewable is worth installing, revealing whether the product exhibits a net positive or net negative effect on the environment.

In the case of PV panels, recycling them after use can be complicated. For example, according to the Environmental Protection Agency, some crystal silicon solar panels don't get recycled and end up in landfills.

But incentives are driving change. The International Renewable Energy Agency states that by "2030, the cumulative value of recoverable raw materials from end-of-life panels globally will be about $450 million, which is equivalent to the cost of raw materials currently needed to produce about 60 million new panels. Diverting solar panels from landfills to recycling saves space in landfills in addition to capturing the value of the raw materials."

The renewables sector isn't perfect, but there is certainly opportunity for improvement and positive outcome. This brings us to Fraunhofer Center for Silicon Photovoltaics CSP and the Fraunhofer Institute for Solar Energy Systems ISE, who recently gained headlines for their research into recycling solar panels.

The Process

Fraunhofer CSP and Fraunhofer ISE focused on solar panels installed in Germany around 2009 that would be entering their end-of-life stage within the next decade.

A research group from the Fraunhofer CSP partnering with Reiling GmbH & Co. KG, one of Germany's leading solar panel recyclers, have discovered a way to separate silicon from the panels for reuse in new panels.

According to Fraunhofer ISE's website, the process works by collecting cell fragments during a mechanical recycling process. Next, chemical etching removes the back, silver, anti-reflective layer, and emitter.

Then, "the silicon cleaned in this way is processed into monocrystalline or quasi-monocrystalline ingots in standard processes and then into wafers."

"The wafers made of recycled silicon were fabricated into PERC solar cells at Fraunhofer ISE's PV-TEC. In the first trial, the solar cell conversion efficiency was 19.7 percent."

Prof. Dr. Peter Dold, the project manager at Fraunhofer CSP, said this efficiency level is less than modern solar panels but is still a noteworthy outcome considering the manufacturing date of those being recycled.

Fraunhofer ISE's website also states that their system provides the possibility "to recycle all crystalline silicon PV modules, regardless of manufacturer and origin." The process can help dispose of older solar panels responsibly and recycle the silicon into new panels, saving money, time, waste, and emissions - indirectly helping to grow the solar industry tenfold.

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