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New Heat-Based Method for Recycling Aging Solar Panels Could Reduce the E-Waste Problem

Solar panels begin to lose efficiency after about 15-20 years, although there’s some debate as to how much longer they can stay in service before they outlive their useful life. At some point, like all things, they do wear out. And they’re notoriously toxic and hard to recycle. It’s an issue that needs to be addressed now, rather than allowing an avalanche of E-waste to hit us unawares when today’s wave of PV panels wear out. One excellent study done at Queens University in Canada in 2010 analyzed the recycling prospects for solar panels, and found the process too expensive for recyclers to make a profit, despite the presence of valuable materials in the panels, such as silver, silicon wafers, and rare metals.
Fortunately, a new recycling process, developed by Korea Electronics Technology Institute and the Korea Interfacial Science and Engineering Institute., could tip the balance in favor of recycling. It saves much of the panels without the normal high environmental cost. This process, which is heat based, has been the subject of more recent research. You can download a full report titled “Thermal treatment of waste photovoltaic module for recovery and recycling: Experimental assessment of the presence of metals in the gas emissions and in the ashes” from this site.

The South Korean process works like this, according to Recycling International:

“The panels are first heated to 480°C in a furnace, thus vaporising the glue that holds the silicon wafers inside, he has explained to Chemistry World magazine. A key discovery was that no wafers break during the heating process if the temperature is ramped up by exactly 15°C per minute.

Once an unbroken wafer has been removed from the panel, its silver electrode is stripped from the top surface using nitric acid. The anti-reflective coating, emitter and the p–n junction layers are then pulverised in a grinding machine. Finally, potassium hydroxide etches away the aluminium electrode from the rear side of the wafer.”

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