Hydrogen generated from solar energy could significantly reduce reliance on fossil fuels and help lower carbon emissions. In the Neo-PEC research project, Fraunhofer scientists have developed a self-sufficient tandem module that produces green hydrogen using solar power.

Hydrogen is essential for transforming industrial processes with minimal climate impact. A CO2-free fuel like hydrogen should also be produced with no carbon footprint. One approach is electrolysis, where water is split into hydrogen and oxygen using electricity from renewable sources. However, this method requires complex, large, and costly electrolyzers, which are in short supply.

A promising alternative is photoelectrochemical cells (PECs), which directly use solar energy to split water. Fraunhofer’s tandem PEC module enables flexible hydrogen generation. Unlike traditional photovoltaic cells, this module integrates the entire process, generating hydrogen and oxygen within a single unit.

To build the tandem cell, experts coat glass with semiconducting materials on both sides. Short-wavelength light is absorbed on one side, while long-wavelength light passes through to the reverse. Hydrogen is produced on the reverse side (cathode), and oxygen on the upper side (anode). Over three years, Fraunhofer scientists optimized semiconductor materials, using ultra-thin coatings to increase hydrogen yield.

The reactor, with an active area of 0.5 square meters, can generate over 30 kilograms of hydrogen annually when scaled to 100 square meters. This amount could fuel a hydrogen car for 15,000 to 20,000 kilometers. The module is stable and compact, making it scalable from single units to large arrays.

The project showcases collaboration across Fraunhofer institutes and demonstrates successful field tests, with future plans to develop the technology further for decentralized hydrogen generation.

Here you can find the original press release.