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A team of Korean researchers developed a hot process to recover silicon wafers without shattering them.
New achievements in the field of photo voltaic module recycling: a team of South Korean researchers developed a sustainable process to reclaim silicon wafers from old photo voltaic units and reintegrate them in the production process, creating new modules. In 2015 alone, South Korea is expected to dismantle 50 thousand tons of solar panels.
The system was developed by the Korea Electronics Technology Institute and the Korea Interfacial Science and Engineering Institute. Their revolutionary approach is the first of its kind that does not utilize highly toxic chemicals such as hydrofluoric acid.
Panels are heated in a furnace to the temperature of 480°C. At this point, the glue that holds the silicon wafers together evaporates. The strength of this system is that the wafers don’t break during the process if the temperature is increased by 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. All other layers are then pulverised in a grinding machine. Finally, potassium hydroxide etches away the aluminium electrode from the rear side of the wafer.
This new method could be the key for the development of solar energy, a clean and renewable source which however comes with considerable economic and environmental costs for the production and disposal of photo voltaic modules. This technology is relatively young: most installed panels are still operational and are expected to last up to 30 years. However, waste deriving from photo voltaic modules is going to increase dramatically in the near future, and we will have to be ready to treat them.