Optical innovations for solar modules—which are the most promising?

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 colored solar modules for facades.

Now, 27 experts provide a comprehensive overview of the state of research and assess the most promising innovations. The report was coordinated by HZB scientists Prof. Christiane Becker and Dr. Klaus Jäger and published in the journal Advances in Optics and Photonics.

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.

“At a recent workshop, we discussed how the optics community can contribute to the further growth of photovoltaics,” says Prof. Becker, head of the Solar Energy Optics Department at HZB.

Becker and her colleague Dr. Jäger then invited international experts to compile a comprehensive overview of PV technologies and optical innovations. In total, 27 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 enabling 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 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 minimizing the consumption of critical raw materials are also discussed. Another chapter is devoted to colored solar modules and 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.

Becker and Jäger are convinced that this comprehensive review does not only help the scientific community, but also decision makers in research funding.