Why are recycling solutions currently and in future gaining more relevance to the solar industry?
Dr. Sylke Meyer: “There are several drivers – one being the anticipated wave of used modules. Another key driver is the goal of reducing dependency on primary raw materials through circular use. Another key long-term theme I foresee is the substitution of critical materials that might present disposal problems. Such issues can be addressed by fostering “design-for-recycling” approaches. Considering the carbon footprint per produced module is also expected to gain importance in the long term – which could lead to an increased use of biopolymers. Recycling technologies will also have to be found for this. The goal in the photovoltaic market should be a genuine circular economy where as many materials incorporated in the modules as possible end up again in the product cycle with the highest possible value created. Theoretically up to 95% of a module can be recycled.”
Can you briefly explain how the recycling of photovoltaic modules works at present?
Dr. Sylke Meyer: “End-of-life modules are first taken to a recycling company. There, those materials firmly connected to each other are separated – meaning the aluminium frame, connector socket and glass are separated from the laminate. These individual components are shredded and cleaned. Thermal processes (melting), mechanical processes (grinding and sieving) and chemical processes (solvents, acids, caustic solutions) are used to separate the materials from each other. The different technological routes can also be combined in this process. At present, mechanical shredding is applied primarily. The resulting material mix in the form of particles of different sizes then has to be elaborately separated and cleaned by means of mechanical, physical and chemical processes. Since aluminium frame and glass account for more than 80% of the weight of a PV module, the well-established recycling technologies currently focus on these materials. For other materials such as silicon and plastics various processes are under development.”
Which technologies and methods are applied in the project to improve the material quality of recycled solar module components?
Dr. Sylke Meyer: “Various separation techniques are tested that ensure a higher quality of the reclaimed glass. Furthermore, new ways of returning silicon into the production cycle are being studied, using only a few hydrometallurgical cleaning steps. At Fraunhofer CSP we contribute our expertise in material analytics and characterisation to RETRIEVE as we can offer ultra-modern equipment. This includes Inductively Coupled Plasma - Mass Spectrometry ICP-MS, a method for inorganic element analysis, and Laser Induced Breakdown Spectroscopy (LIBS), which makes possible an in-line analysis of element contents. We also undertake in-depth cooperation to optimise the processes involved in the various cleaning and downstream processing steps.”
What impact do you expect the project to have on the photovoltaic value chain and the circular economy as a whole?
Dr. Sylke Meyer: “We want to help ensure that valuable resources can continue to be used in a meaningful way achieving the highest grades possible. It is only logical to also think of the circular economy in photovoltaics, which is meant to supply us with green electricity. Both are oriented towards sustainability and can bolster each other in achieving this goal in the best-case scenario. Innovative recycling approaches can prove a competitive edge especially for the European industry – for the PV industry as well as for upstream material suppliers and above all for the recycling industry itself.”
In general: What are the challenges you see in the field of research and development for the future?
Dr. Sylke Meyer: “For recycling profitability is, of course, a key issue. On the highly competitive PV market manufacturers have very little scope for passing on added costs to customers for especially sustainably manufactured modules. It is therefore important to develop both affordable recycling processes and attractive markets for the use of recyclates from PV modules. I see considerable opportunities in economies of scale here: especially due to the large quantity of end-of-life modules the development of matching processes can pay off, which in turn can lead to a larger supply and, hence, falling recyclates prices.
In view of the solar industry as a whole: we should not only look at efficiency rates and cost reductions but also at the reliability and lifetime of the modules: the longer the modules are intact and in operation, the lower the need for recycling. And our research at the Fraunhofer CSP also contributes to this.”
Thank you very much for the interview!