In recent years, photovoltaics (PV) recycling has grown into a new sector within the PV industry. And it is sorely needed because, according to a study by the International Renewable Energy Agency (IRENA), in Germany alone, the dismantling of used PV modules will produce between 400,000 and 1 million metric tons of electrical waste by 2030. To make the PV industry fully sustainable, PV production must become part of a circular economy
There are a number of promising methods emerging, and some initial projects prove that PV recycling is profitable. However, processes for end-of-life (EOL) management need to become more standardized in order to increase the recycling rate.
The first solar boom in Germany was in 2007. Almost 20 years on, the industry has to find a solution to the question of what to do with used modules when solar parks are dismantled at the end of their service life. The typical life span of a solar module is 20 to 30 years. At present, the amount of PV waste is small, but it is set to rise strongly. By 2050, 78 million metric tons of obsolete PV modules are expected worldwide. According to EUROSTAT, in 2021, Europe already produced 30 metric tons of electrical waste from used modules.
When it comes to standard silicon solar cells, the latest technology is able to recover glass, silicon, silver, copper, plastic and aluminum. Thin-film modules contain indium, gallium, tellurium, glass and copper, which can all be recycled. There are several reasons why recovering the raw materials and reintegrating them into the material cycle is key. Silver accounts for 10 percent of the production cost of a PV module, and around 30 percent of industrial demand for silver already comes from the solar industry. Recovering valuable raw materials makes production more profitable, saves resources and enables the quick expansion of solar energy. The circular economy is essential to establish solar energy as a sustainable energy production technology. Recycling also plays an important role in preventing improper disposal of waste that contains hazardous substances such as cadmium, arsenic, lead, antimony and fluoropolymers.
The most obvious question seems to be whether the recovered materials can be reused in the production of new PV modules. At present, glass, which accounts for 70 to 75 percent of a standard PV module, cannot be recycled with the level of purity required for it to be reused as PV glass. That is why, at least in Europe, reusing glass in other industries makes much more sense. What’s more, transporting recycled materials to China, where most of the world’s PV production takes place, would make neither financial nor ecological sense.
Since 2012, PV waste is subject to the updated Waste Electrical and Electronic Equipment (WEEE) Directive. Solar modules must be treated – and recycled – like any other electrical waste. The EU currently demands a PV collection rate of 85 percent, and 80 percent must be reintroduced into the material cycle. The EU Extended Producer Responsibility standard extends producers’ responsibility for a product to observe reuse and recovery rates. The rule only applies to modules marketed from 2015, though.
There are different recycling processes for PV: mechanical, thermal and chemical, or a combination thereof. The mechanical process is still the standard: The modules are shredded, then the material is separated and sorted. The combination of a mechanical and a chemical process uses a chemical solution after shredding in order to dissolve and extract as many materials as possible. Innovative thermal solutions attempt to reduce the need for chemical methods to improve sustainability and increase the recovery rate by reducing shredding. These methods use light pulses, lasers, high-pressure water jets, infrared lights or the “hot knife” technology to separate the back sheet from the module. Pyrolysis uses a combination of mechanical, chemical and thermal methods.
Reiling PV-Recycling is part of the Reiling Group, an established German glass recycling company. In 2024, they expect to recycle 10,000 metric tons of used modules. The company’s new site in Münster, Germany, is dedicated to PV recycling and will be able to process up to 50,000 metric tons per year. Reiling PV-Recycling uses a traditional mechanical process for maximum throughput. In addition to the mechanical process, the company has recently made progress with silicon recovery.
In 2023, ROSI opened a factory with an annual throughput of 3,000 metric tons in Grenoble, France. This is an industrial-scale pioneering project that recovers around 99 percent of raw materials while maintaining profitability. Rosi’s annual turnover is around eight million euros. The methods used are pyrolysis and a combination of mechanical, thermal and chemical processes. Another site in Elsnig, Germany, with an initial annual capacity of 10,000 metric tons is set to open in 2025. The company is also preparing to open another site in Teruel, Spain.
One of several global recycling plants of First Solar, a large solar company from the U.S., is located in Frankfurt an der Oder, Germany. The plant has a focus on recycling thin-film modules and successfully fills a niche in the market. The First Solar plant in Frankfurt recycled 10,000 metric tons of modules in 2022. The process uses a combination of mechanical and chemical methods, which, according to the operator, allows to recover 90 percent of all materials.
Flaxres from the German city of Dresden is one of the most innovative start-ups within the PV recycling scene. The process uses a flashing unit that exposes the module to a very short, high-intensity light pulse for delamination (flash lamp annealing). This recycling technology is available for mobile application. Built into oversea containers, it can be transported to the dismantling site for on-site recycling, avoiding the costly transport of used modules. The equipment can be rented on a monthly basis and the technology is also suitable for recycling thin-film modules. The first five recycling units are set to be launched in 2024.
Solar Materials, a start-up company from Magdeburg, Germany, claims to achieve a recovery rate of 98 percent. The pilot plant has an annual capacity of 3,000 metric tons and employs a thermo-mechanical process. The company has plans to build its own plant, which will increase throughput to 10,000 metric tons by summer 2025.
Start-up companies and PV manufacturers have already developed some needs-based, innovative solutions. Operating a PV recycling plant in a profitable way has so far been difficult, which has largely been due to the low volume of material for recycling available. Creating capacities for PV recycling while upholding high quality and maximizing the volume of recovered material remains a challenge, though.
According to a study by the International Energy Agency (IEA), Germany could still improve sorting and coordination in public collection plants. A large part of recycling costs are owed to avoidable transportation costs for taking modules from a collection point to a suitable processing plant. The study also found that many still functioning modules are damaged during handling, which impairs their reusability potential. This problem could be solved through staff training. Industry representatives agree that we will need a digital system for recording and monitoring PV waste streams to prevent modules from being transported to third countries for the purpose of uncontrolled trade.
One of the challenges for recycling technology is that producers focus on a long service life – which makes modules more difficult to recycle. The new EU Ecodesign Directive could bring some improvement by requiring better recyclability.