Expanding solar production is key to reducing global emissions. Solar panels are produced worldwide 720 terawatt hours energy in 2019, which represents about 3% of world electricity production. And it took about 46 million metric tons of solar panels to do it.
About 8 million metric tons of decommissioned solar panels could accumulate worldwide by 2030. By 2050, that number could reach 80 million. Recycling these panels could provide a new source of materials that would otherwise have to be extracted (potentially under hazardous or exploitative working conditions), turning solar energy into a more sustainable piece of the clean energy puzzle.
What’s in the solar panel?
The solar panels are arranged like a sandwich with cells in the center. About 90% of commercial solar panels use silicon as a semiconductor that converts light into electricity. Thin metal strips, usually silver, cross the surface of the silicon crystals in each cell and move electricity into the copper wires of the panel.
Solar cells are wrapped in a protective barrier, usually a clear plastic called EVA. Another layer of glass goes on top, and a different type of plastic, such as PET, covers the back. The whole thing is surrounded by an aluminum frame.
This multilayer construction protects the cells from the elements while letting in sunlight, but can be difficult to deconstruct when the panels have reached the end of their life.
Some companies are trying to repair and reuse panels that have lost efficiency, or at least save some of their components. Reuse is the simplest and cheapest way to “recycle” panels – it requires the least processing and commands the highest cost.
The panel can cost about $ 55, while a used panel can be resold for about $ 22. Or the components of a used panel can be sold for a total of up to $ 18, depending on Meng Tao, a professor of engineering at Arizona State University and founder of a solar panel recycling company called TG Companies.
Although some distributors offer used panels for sale to residential customers, they do not offer much cost savings. The panels make up at most about half the cost of a residential solar array, with other equipment and allow the rest to be accounted for. Given that the panels used do not generate as much electricity, the money saved from their purchase may not be worth it.
The panels used, which cannot be resold, are intended either for a landfill or for some kind of recycling. In the absence of federal mandates, Washington recently adopted recycling requirements for producers, and other countries are now considering doing the same. The EU, meanwhile, requires manufacturers to collect and recycle used solar panels and to fund research into obsolete resources for the technology they produce.
Some waste facilities can recycle solar panels using mechanical methods. Most come out of an aluminum frame and grind all the glass, silicon and other metals into a mixture called a glass box, which can be sold for building materials or other industrial applications.
But glass stone does not cost much – about $ 3 for the value of the mixture per panel. And it is unclear whether there will be buyers for all the glass that would result from recycling many more solar panels, Tao said. The ability to retrieve clean, valuable materials can help make recycling more profitable.
In 2018, the waste management company Veolia, based near Paris, opened the first, according to her, recycling line, developed specifically for the recycling of solar panels. Located in Ruse, France, the plant also uses a mechanical recycling process, although because it is designed for solar panels, more components are recycled separately than in facilities using common e-waste recycling equipment. But some companies are betting that other methods, such as thermal and chemical processes, will be even more effective.
Extracting old panels
ROSI Solar, a French startup founded in 2017, recently announced plans to build a new recycling plant in Grenoble, France. Yun Luo, CEO of ROSI, says the company has developed a process to extract silver, silicon and other high-quality materials from the panels used. The plant should open its doors before the end of 2022 with a contract from Soren, a French trade association.
Soren is also working with a French logistics company called Envie 2E Aquitaine, which will try to find other applications for decommissioned solar panels. If the panels do not work, the company will remove the aluminum frame and glass before handing them over to ROSI for recycling, Lo said.
ROSI focuses on the recovery of silver and silicon from the solar class, as these two materials make up over 60% of the price of the panel. The company uses a patented chemical process on the remaining layers, focusing on removing the small silver fibers that transmit electricity through a working solar panel.
Luo declined to go into details, but said the company could recover almost all of the silver in solid form, making it easier to separate from other metals, such as lead and tin. Luo says the company is also restoring silicon in pure enough form to reuse it in new panels or EV batteries.
To be profitable, ROSI will have to recycle at least 2,000 to 3,000 tons of panels a year, Lo said. Soren expects to assemble about 7,000 tons of panels in 2021, and that number is likely to double by 2025.