When solar panels reach their end of their life today, they face a few possible fates. Under EU law, producers are required to ensure their solar panels are recycled properly. In Japan, India, and Australia, recycling requirements are in the works. In the United States, it’s the Wild West: With the exception of a state law in Washington, the US has no solar recycling mandates whatsoever. Voluntary, industry-led recycling efforts are limited in scope. “Right now, we’re pretty confident the number is around 10 percent of solar panels recycled,” said Sam Vanderhoof, the CEO of Recycle PV Solar, one of the only US companies dedicated to PV recycling. The rest, he says, go to landfills or are exported overseas for reuse in developing countries with weak environmental protections.

Even when recycling happens, there’s a lot of room for improvement. A solar panel is essentially an electronic sandwich. The filling is a thin layer of crystalline silicon cells, which are insulated and protected from the elements on both sides by sheets of polymers and glass. It’s all held together in an aluminum frame. On the back of the panel, a junction box contains copper wiring that channels electricity away as it’s being generated. 

At a typical e-waste facility, this high-tech sandwich will be treated crudely. Recyclers often take off the panel’s frame and its junction box to recover the aluminum and copper, then shred the rest of the module, including the glass, polymers, and silicon cells, which get coated in a silver electrode and soldered using tin and lead. (Because the vast majority of that mixture by weight is glass, the resultant product is considered an impure, crushed glass.) Tao and his colleagues estimate that a recycler taking apart a standard 60-cell silicon panel can get about $3 for the recovered aluminum, copper, and glass. Vanderhoof, meanwhile, says that the cost of recycling that panel in the US is between $12 and $25—after transportation costs, which “oftentimes equal the cost to recycle.” At the same time, in states that allow it, it typically costs less than a dollar to dump a solar panel in a solid-waste landfill.