Solar panels are an increasingly important source of renewable energy that will play an essential role in the fight against climate change. They're also complex pieces of technology that turn into big, bulky pieces of e-waste at the end of their lives, and right now, most of the world doesn't have a plan for dealing with that.
But we'll need to develop one soon, because excess solar e-waste is coming. By 2050, the International Renewable Energy Agency projects that up to 78 million metric tons of solar panels will have reached the end of their useful life, and that the world will generate about 6 million metric tons of new solar e-waste per year. While the latest number is a small fraction of the total e-waste humanity produces each year, standard electronic recycling methods are not enough for solar panels. Recovering one's most valuable materials, including silver and silicon, requires bespoke recycling solutions. And if we don't develop those solutions alongside policies that support their widespread adoption, we already know what will happen.
"If we don't enforce recycling, a lot of the modules will go to landfill," said Arizona State University solar researcher Meng Tao, who recently wrote a review article on recycling silicon solar panels, which comprise 95 percent of the solar market.
Solar panels are made up of photovoltaic (PV) cells that convert sunlight into electricity. When these panels go into landfills, valuable resources are wasted. And because solar panels contain toxic materials like lead that can leach out as they break down, landfills also create new environmental hazards.
Most solar power manufacturers claim that their panels will last about 25 years, and the world did not begin to deploy solar power widely until the early 2000s. As a result, today a fairly small amount of solar panels. PV CYCLE, a non-profit organization dedicated to the recovery and recycling of solar panels, collects several thousand tonnes of solar e-waste throughout the European Union each year, according to director Jan Clyncke. That figure includes solar panels that have reached the end of their useful life, but also those that were withdrawn from service early because they were damaged in a storm, had some type of manufacturer defect, or were replaced with a newer model, and efficient.
When solar panels reach the end of their life today, they face a few possible fates. Under EU law, producers must ensure that their solar panels are recycled properly. In Japan, India and Australia, recycling requirements are in process. In the United States, it's the Wild West: With the exception of a state law in Washington, the US has no solar recycling mandate. Industry-led voluntary recycling efforts are limited in scope. "Right now, we're pretty sure the number is around 10 percent for recycled solar panels," said Sam Vanderhoof, CEO of Recycle PV Solar, one of the only US companies dedicated to photovoltaic recycling. The rest, he says, go to landfills or are exported abroad for reuse in developing countries with weak environmental protections.
Even when recycling occurs, there is a lot of room for improvement. A solar panel is essentially an electronic sandwich. The filler is a thin layer of crystalline silicon cells, which are isolated and protected from the elements on both sides by polymer and glass sheets. Everything is held together in an aluminum frame. At the rear of the panel, a junction box contains copper wiring that channels electricity as it is generated.
Recyclers often remove the panel frame and its junction box to reclaim the aluminum and copper, then shred the rest of the module, including the glass, polymers, and silicon cells, which are coated with a silver electrode and they are soldered with tin and lead. (Because the vast majority of that mixture by weight is glass, the resulting product is considered impure crushed glass.) Tao and his colleagues estimate that a recycler who takes apart a standard 60-cell silicon panel can get around $ 3 for the recovered material: aluminum, copper and glass. Vanderhoof, meanwhile, says that the cost of recycling that panel in the US ranges from $ 12 to $ 25, after transportation costs, which "often equate to the cost of recycling." At the same time, in states that allow it, "we think the big blind spot in the United States for recycling is that the cost far exceeds the revenue," Meng said. "It's on the order of a 10 to 1 ratio."
If the most valuable components of a solar panel, namely silicon and silver, could be efficiently separated and purified, that could improve cost-income. A small number of dedicated solar photovoltaic recyclers are trying to do this.
Veolia, which operates the world's only commercial-scale photovoltaic silicon recycling plant in France, shreds and shreds panels and then uses an optical technique to recover low-purity silicon. According to Vanderhoof, Recycle PV Solar initially used a "heat process and ball mill process" that could recover more than 90 percent of the materials present in a panel, including silver and low-purity silicon. But the company recently got some new equipment from its European partners that can do "more than 95 percent recovery," he said, while separating recovered materials much better.
Some PV researchers want to do even better than that. In another recent review article, a team led by scientists from the National Renewable Energy Laboratory calls for the development of new recycling processes where all metals and minerals are recovered with high purity, with the aim of making recycling the most economical. feasible and as beneficial to the environment as possible. As the study's lead author Garvin Heath explains, such processes could include the use of heat or chemical treatments to separate the glass from the silicon cells, followed by the application of other chemical or electrical techniques to separate and purify the silicon and various trace metals.
"What we are asking for is what we call a high-value integrated recycling system," Heath told Grist. “High value means that we want to recover all the constituent materials that have value from these modules. Integrated refers to a recycling process that can go after all these materials and not have to cascade from one recycler to another ”.
In addition to developing better recycling methods, the solar industry should think about how to reuse panels whenever possible, as used solar panels are likely to command a higher price than the metals and minerals they contain (and since reuse generally requires less energy than recycling). As is the case with recycling, the EU is at the forefront in this: through its circular business model program for the solar energy industry, the European Commission is funding a series of demonstration projects showing how they can be reused. rooftop solar panels and solar farms, even to power electric bike charging stations in Berlin and housing complexes in Belgium.
Recycle PV Solar also recertifies and resells undamaged panels it receives, which Vanderhoof says helps offset the cost of recycling. However, both he and Tao are concerned that several US recyclers are selling second-hand, quality-controlled solar panels abroad to developing countries. "And those countries usually don't have regulations for e-waste," Tao said. "So eventually, you are turning your problem into a poor country."
For the solar recycling industry to grow sustainably, it will ultimately need supportive policies and regulations. The EU model of having producers finance the recovery and recycling of solar panels could be good for the United States to emulate. But before that happens, US lawmakers must recognize that the problem exists and is only growing, which is why Vanderhoof spends a lot of time educating them.
"We have to face the fact that solar panels fail over time, and there are a lot of them," he said. “And what do we do when they start to fail? It is not correct to put that responsibility on the consumer, and that is where we are now.