The circular economy is front and centre when it comes to new materials, dictating the need for research into their recyclability in the early stages of development. This also applies to photovoltaic modules made of perovskite, an alternative to the classic silicon module. Research scientists at the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (Zentrum für Sonnenenergie- und Wasserstoff-Forschung - ZSW) are now working with two industry partners to investigate how end-of-life thin-film solar modules can be reused. The partners in the new “PeroCycle” project want to develop an industrially viable recycling process for perovskite solar modules in four steps. Perovskite is an attractive option for the photovoltaic industry. When paired with silicon in a tandem module, the material significantly increases efficiency and can be manufactured and scaled up inexpensively.
Germany has ambitious expansion targets in the field of renewable energy sources, which can only be met by acting in accordance with the principle of the circular economy. This means using finite resources wisely and for a long time. After the end of the service life of a PV module, a high degree of recyclability and reuse is more important than ever. This is the focus of the new “PeroCycle” project and is central to the research brief for the ZSW, Solaveni GmbH of Bönen and Solar Materials GmbH of Magdeburg. Solaveni brings expertise from the chemical processing of perovskite materials while Solar Materials specialises in the purely physical separation of composite materials without the use of chemicals. The research scientists at the ZSW can draw on over 30 years of experience with thin-film solar modules and over ten years of materials research on perovskite solar cells and modules. The German Federal Environmental Foundation (Deutsche Bundesstiftung Umwelt - DBU) is funding the joint project.
Making perovskite modules recyclable
The aim of the research team is to develop an industrial recycling process to enable the optimum reutilisation of end-of-life modules. The first step to this end is the manufacture and encapsulation of perovskite mini-modules at the ZSW.
“Given the sharp increase in the number of PV module installations, there is always a need to consider the issue of recycling, and this must be done at an early stage in case of new technologies like perovskite solar modules,” said ZSW employee Dr. Cordula Wessendorf, talking about the PeroCycle project.
Thermomechanics for clean separation
The second step calls for the use of thermomechanical processes at Solar Materials for the separation of the encapsulated perovskite modules. This involves testing whether the glass-polymer composite and therefore the glass as a whole can be effectively separated from the perovskite absorber material. Unlike conventional shredding processes, there is no mixing with other materials in this case. The glass can therefore be processed into container glass. The perovskite absorber material is collected separately.
Recycling process with eco-friendly solvents instead of toxic solvents
Step three follows the separation of the materials and entails the development and optimisation of a perovskite recycling process at Solaveni. Non-flammable, cost-effective and environmentally-friendly solvent systems have been developed specifically for the recycling process, obviating the need for toxic solvents and avoiding the deployment of extreme conditions, such as high temperatures. The new approach reduces energy consumption and waste, making it possible to cut costs and minimise environmental impact. The future recycling method includes chemical and physical processing techniques. The aim is to recover at least 90 per cent of the perovskite with a purity of 99 per cent.
Using recycled materials for new modules
The fourth and final step will be to make a new perovskite module at the ZSW from the materials obtained. The recycled perovskite absorber material and the recycled glass coated with transparent contacts will be used for this purpose. The research scientists in the materials laboratory aim to achieve at least 90 per cent of the efficiency of the freshly produced reference samples from the recycled materials.
Improving recycling options for PV modules already on the market in Germany
The ZSW, in collaboration with the Fraunhofer IBP and in liaison with the PVPS Task 12 members at the International Energy Agency (IEA), published a report on the current status of recycling of PV modules in Germany in March of this year in the predecessor project “RePotPV”. Given the high rate of expansion of photovoltaic systems, it is becoming increasingly important to enhance end-of-life management in terms of its efficiency and industrial viability. Germany was one of the first countries to install photovoltaic systems on a grand scale and is therefore now faced with the earlier onset of the challenge of developing and applying recycling options for photovoltaic modules. In order to remain internationally competitive with new PV technologies as well, the aims are to think through the recycling of PV modules right from the outset and to achieve industrial viability using new processes.
The report on the current status of PV recycling in Germany can be found here: https://iea-pvps.org/key-topics/status-of-pv-module-take-back-and-recycling-in-germany/
The ZSW will be presenting the latest developments in PV recycling at the PV recycling workshop on 14 and 15 October 2024 in Stuttgart. In addition to scientific lectures and a tour of the ZSW laboratory, those attending will be able to benefit from opportunities to talk to key players in industry and research. For more information and registration options please visit: www.zsw-bw.de/mediathek/veranstaltungen/detailansicht/news/detail/News/pv-recycling-workshop-am-zsw.html