SunHydrogen, the developer of a breakthrough technology to produce renewable H₂ using sunlight and water, shared strong test results from a recent trip to Japan where members of the SunHydrogen team collaborated with consultants Prof. Kazunari Domen, Dr. Hiroshi Nishiyama and Dr. Taro Yamada at the University of Tokyo and visited the Honda R&D facility in Tochigi.

Breakthrough in large area solar-to-H₂ efficiency. At Prof. Domen’s laboratory at the University of Tokyo, SunHydrogen conducted large-area solar testing of its 1,200 cm² H₂ modules, manufactured in collaboration with CTF Solar, that comprised the company’s recent 1m² demonstration system.

SunHydrogen is pleased to report that the 1,200 cm² modules demonstrated an active-area solar-to-H₂ efficiency of 9%. Importantly, this marks the highest reported efficiency for a H₂ module of this size.

Previously, SunHydrogen validated an efficiency exceeding 10% in its 100 cm² H₂ modules, tested at Honda R&D. The current results demonstrate that even after scaling up tenfold, the company remains close to the 10% active-area efficiency threshold – an achievement that underscores the viability of its technology at larger scales.

Additionally, the modules were tested under wide temperatures, ranging from 5°C to 40°C and their efficiency remained stable across the full temperature range. The team utilized a state-of-the-art LED solar simulator, uniquely capable of simulating the solar spectrum over a large enough area to test modules of this scale.

“Scaling up tenfold presents unique challenges, and we are extremely pleased to have maintained such high efficiency in our first large-area test. To our knowledge, this remains the highest reported efficiency for a H₂ module of this scale,” said SunHydrogen’s CEO Tim Young.

“These results give us confidence that with further design optimization, including maximizing active water-splitting area and refining catalyst loading, we can push efficiencies to 10% and beyond in future generations of larger modules,” said SunHydrogen’s Chief Technology Officer Dr. Syed Mubeen. “We are also thrilled to come away from this trip with critical data confirming the stability of our H₂ modules under varying temperatures.”

Advancing real-world testing with Honda. Following its laboratory testing at the University of Tokyo, the SunHydrogen team visited its joint development partners at Honda R&D in Tochigi, Japan. At their facilities, the team observed on-sun rooftop testing of SunHydrogen’s 100 cm² H₂ modules.

 “We were particularly impressed by Honda’s innovative housing unit design, which enables H₂ and oxygen separation without the use of membranes – a first-of-its-kind approach – and we will continue ongoing testing of the 100 cm² modules,” Dr. Mubeen said.

Honda will soon test SunHydrogen’s 1,200 cm² modules under on-sun conditions using a similar rooftop setup, and SunHydrogen is eager to utilize the performance data from these extended tests to further refine its module design.

“Our visit to Japan provided valuable insights and key validation for SunHydrogen’s technology in both controlled laboratory conditions and real-world outdoor environments,” Mr. Young said. “The University of Tokyo’s unique solar simulator enabled the most comprehensive and precise efficiency testing of our large-area modules to date, while Honda’s membrane-free separation approach represents a significant milestone in real-world implementation. We extend our sincere gratitude to the entire Honda R&D team under the leadership of Mr. Yuichi Matsuo, as well as to Prof. Domen, Dr. Yamada and Dr. Nishiyama.”