Optical innovations for solar modules - which are the most promising?
Symbolic picture with Microsoft Copilot.
In 2023, photovoltaic systems generated more than 5% of the world’s electrical energy and the installed capacity doubles every two to three years. Optical technologies can further increase the efficiency of solar modules and open up new applications, such as coloured solar modules for facades. Now, 27 experts provide a comprehensive overview of the state of research and assess the most promising innovations. The report, which is also of interest to stakeholders in funding and science management, was coordinated by HZB scientists Prof. Christiane Becker and Dr. Klaus Jäger.
Photovoltaics (PV) has become one of the most cost-effective technologies for generating electricity. In November 2024, the world’s photovoltaic systems reached an installed capacity of two terawatts, and the growth rates and cost reductions are still enormous.
Expertise from 22 research institutions
‘At a recent workshop, we discussed how the optics community can contribute to the further growth of photovoltaics,’ says Prof. Christiane Becker, head of the Solar Energy Optics Department at HZB. Christiane Becker and her colleague Dr. Klaus Jäger then invited international experts to compile a comprehensive overview of PV technologies and optical innovations. In total, 27 renowned experts from 22 research institutions in 9 countries contributed to the review.
Most promising concepts
The article begins with an overview of the current state of photovoltaics on a terawatt scale. From this, the experts identify issues and topics, where the optics community can contribute to enable large-scale deployment. ‘We have also identified a number of optical concepts that are currently only on the threshold of economic viability, but which hold the most promise for advancing PV technology,’ says Christiane Becker. These include optical innovations in the field of multi-junction solar cells, which have the highest efficiencies and therefore have great potential to further reduce the levelized cost of electricity.
Ecological aspects
Improved manufacturing processes using an eco-design approach and minimising the consumption of critical raw materials are also discussed. Another chapter is devoted to coloured solar modules as building integrated PV solutions. ‘Especially in cities, we need to use facades and other surfaces too for solar energy conversion, and of course, it does matter how the PV modules look. Such innovative solar modules allow sophisticated aesthetic solutions,’ says Becker.
Christiane Becker and Klaus Jäger are convinced that this comprehensive review does not only help the scientific community, but also decision makers in research funding.
- Self assembling monolayer can improve lead-free perovskite solar cells tooTin perovskite solar cells are not only non-toxic, but also potentially more stable than lead-containing perovskite solar cells. However, they are also significantly less efficient. Now, an international team has succeeded in reducing losses in the lower contact layer of tin perovskite solar cells: The scienstists identified chemical compounds that self-assemble into a molecular layer that fits very well with the lattice structure of tin perovskites. On this monolayer, tin perovskite with excellent optoelectronic quality can be grown, which increases the performance of the solar cell.
- Scrolls from Buddhist shrine virtually unrolled at BESSY IIThe Mongolian collection of the Ethnological Museum of the National Museums in Berlin contains a unique Gungervaa shrine. Among the objects found inside were three tiny scrolls, wrapped in silk. Using 3D X-ray tomography, a team at HZB was able to create a digital copy of one of the scrolls. With a mathematical method the scroll could be virtually unrolled to reveal the scripture on the strip. This method is also used in battery research.
- Long-term test shows: Efficiency of perovskite cells varies with the seasonScientists at HZB run a long-term experiment on the roof of a building at the Adlershof campus. They expose a wide variety of solar cells to the weather conditions, recording their performance over a period of years. These include perovskite solar cells, a new photovoltaic material offering high efficiency and low manufacturing costs. Dr Carolin Ulbrich and Dr Mark Khenkin evaluated four years of data and presented their findings in Advanced Energy Materials. This is the longest series of measurements on perovskite cells in outdoor use to date. The scientists found that standard perovskite solar cells perform very well during the summer months, even over several years, but decline in efficiency during the darker months.