Researchers in South Korea have developed a method of breaking apart the panels with heat instead of toxic chemicals.
"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."