A four-person spin-off from Germany's Karlsruhe Institute of Technology (KIT) claims to have developed a technology that produces green hydrogen directly from sunlight and water, bypassing the need for separate solar panels and electrolysers. The startup, Photreon, unveiled a working one-square-metre panel at the Hannover Messe trade fair in April 2026. The panel absorbs sunlight and water and releases hydrogen gas without generating electricity at any point. KIT has filed a patent application covering the panel's internal design, though the technology still faces efficiency challenges that have hindered similar efforts for two decades.
What is Photreon's solar hydrogen panel and how does it work
Photreon's product is a photoreactor panel, a flat device that takes in sunlight and water and releases hydrogen gas without ever producing electricity as an intermediate step. The team demonstrated a working one-square-metre prototype at the KIT booth during Hannover Messe, which ran from April 20 to 24, 2026. According to KIT's official announcement, the institute has filed a patent application covering the reactor's internal geometry, the specific arrangement of materials and channels inside the panel that enables the one-step process. Paul Kant, a researcher at KIT's Institute for Micro Process Engineering and Photreon co-founder, stated that the design produces chemical energy directly from sunlight and water, bypassing electrolysis entirely.
How photocatalysis lets this panel skip the electrolyser entirely
The underlying technology is called photocatalysis, a fundamentally different process from standard photovoltaic panels. Instead of converting light into an electric current, Photreon's panel uses light-sensitive materials that absorb sunlight and push electrons into an excited state. These energised electrons immediately drive a chemical reaction that splits water molecules into hydrogen and oxygen inside the panel itself. Kant explained that the reactor's internal geometry is engineered to handle three tasks simultaneously: guiding light onto the active material, running the water-splitting reaction, and extracting the resulting gases efficiently. The last task has historically been the most challenging, as a panel that produces hydrogen but cannot collect it cleanly has limited practical use.
Why photocatalytic hydrogen panels have struggled with low efficiency
Despite the elegant concept, photocatalysis has a long history of poor real-world performance. A widely cited study published in Nature in 2021 measured real-world photocatalytic water-splitting efficiency at around 1%, far below the 30% achieved by lab systems that pair solar cells with electrolysers. The same research documented a 100-square-metre outdoor demonstration array in Japan that ran for a year and peaked at just 0.76% efficiency. A later 2023 study using an indium gallium nitride catalyst under concentrated sunlight reached a best-published figure of 9.2%, though that dropped to about 7% when tested with ordinary tap water and seawater. Researchers generally consider 10% as the threshold needed for the technology to become commercially viable.
How Photreon plans to make cheap hydrogen panels commercially viable
Rather than chasing efficiency records, Photreon is betting on manufacturing cost. The panel is designed around standard mass-production techniques and inexpensive materials, and the system is modular, scaling from a handful of units on a factory roof to thousands of panels wired together into what KIT describes as solar hydrogen farms. Co-founder Maren Cordts framed the appeal in system-level terms, noting that a single panel replaces both the solar array and the electrolyser, cutting cost and complexity at once. The company is targeting mid-sized manufacturers in sectors such as speciality chemicals, food production, and metalworking, along with large solar installations and remote sites that currently lack access to a power grid or hydrogen pipeline.
Who else is racing to build sunlight-to-hydrogen technology
Photreon is not alone in pursuing direct sunlight-to-hydrogen production. Israel's QD-SOL has pursued a similar nanoparticle-catalyst approach and reported connecting multiple photocatalytic panels into a continuously producing array in 2025. SunHydrogen, a publicly traded company based in Iowa, brought in University of Tokyo researchers behind Japan's large outdoor demonstration as consultants in 2023 to help refine its own panel design. Every competitor in this space is working against the same single-digit efficiency ceiling that has constrained the field for two decades. The eventual winner will likely be whichever company first combines an acceptable conversion rate with genuinely low manufacturing costs, a combination that nobody has yet managed to deliver.
