sssh. A large press descends on a table of a few square meters. On top of it is a black plastic tarpaulin and underneath is a small solar panel the size of a record sleeve. Maurice Goris, technical employee in the Solar Lab of the TNO research institute in Petten, has just assembled the solar panel. And now it has to ‘bake’ for fifteen minutes in the laminator at about 150 degrees. The air is squeezed out to make the panel firmer. In principle, all you need to do after this is an aluminum frame and this fully recyclable solar panel could go on the roof.
Solar panels are like toasted sandwiches – they are made up of different layers. The solar cells are in the middle and around it is a thin layer of plastic adhesive film on both sides. At the front is a glass plate and at the back usually a plastic panel. Due to the pressure and heat of the laminator, the adhesive foil fuses with the other materials, making the panels more resistant to weather influences. But this fusion makes reuse of the materials difficult.
Huge waste mountain
Solar panels do not last forever – after about twenty-five to thirty years they are ready for demolition. However, waste processors cannot completely disassemble the panels. That is why they now end up in a pulverizer where they are crushed. Due to this fusion, the glass from the glass plate and the silicon and silver from the solar cells can only be reused in low-value applications such as insulation material, not in new solar panels. To do this, the substances must be as pure as possible and not contaminated with other substances.
The number of solar panels in the Netherlands is growing rapidly. In the past year, total wealth has increased by 48 percent in one year, according to the National Solar Trend Report 2021 from research agency DNE Research. This will produce a huge mountain of waste within a few decades.
There are solar panels on many Dutch homes. View an interactive map of panels and the energy consumption of residential houses here.
The first generation is already coming down from the roofs, says Martin Späth, researcher at TNO, after our visit to the lab space. “That’s maybe seven thousand panels, peanuts. But in 2040, the panels installed from 2015, when the advance began, will be released. We are talking about 100,000 to 200,000 tons of waste. And in 2050 even 400,000 to 500,000 tons.” How are we going to recycle that solar panel waste in a sensible way?
There are a few factories abroad that focus specifically on solar panel recycling and thereby produce purer residual flows. But even those materials are not yet finding their way to a new solar panel. In addition, it contains harmful substances, such as fluorine and lead, which can be released during recycling.
Späth wanted to know if he could solve these pain points and create a fully reusable, circular, solar panel. He came into contact with companies that are developing recyclable and safe materials. The Hague solar panel manufacturer Exasun, for example, uses a glass back panel. Conventional solar panels have a plastic back panel, because that is cheaper, but less moisture-resistant. Manufacturers solve this by incorporating toxic fluorine compounds (such as PFAS) into the material. This makes recycling more difficult, because the fluorine is then released. Eindhoven-based Mat-Tech makes a solder connection, a kind of gray paste, which conducts the electricity from the solar cells well. This usually contains lead, because it lowers the temperature and puts less stress on the solar cells. Mat-Tech replaces the lead for the (non-toxic) material bismuth, which has a lower melting temperature.
Finally, Endurans Solar, a spin-off of chemical company DSM, makes an adhesive film that, despite the fusion, can become completely detached from the other materials. TNO has developed a fairly simple process for this decommissioning, which does not require any special equipment. Späth does not want to say exactly how that works for competitive reasons.
Compete against Chinese panels
With these ingredients, a new, circular, solar panel was assembled in the Pettense lab. One floor below, technical employee Goris shows the climate chambers. These are cabinets in which the panels are exposed to high humidity and strong temperature changes. Goris: “The panels are tested for five hundred hours under 85 degrees and 85 percent humidity. And in the thermal cyclecabinet they cycle a hundred times from -40 to 85 degrees.” Previous versions have survived that process six times with no deterioration in current and voltage, and would therefore be good enough to spend at least twenty-five years outdoors. At the beginning of next year, the large panels will also go through these test areas.
In principle, the new solar panels could be on the roofs next year, but the question is whether they can compete with the large volumes of Chinese solar panels that now dominate the market. The recyclable solar panels could be made for the same cost as conventional panels. But Chinese producers benefit from economies of scale through high-volume production. Späth: “We can set a good example on a small scale in Europe, but recycling legislation remains an obstacle. It must now be possible to recycle 85 percent of the weight of a solar panel, but it is better to focus on preserving value than on weight. Only then will producers feel the need to switch to a circular design.”
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