German researchers claim self-sufficient hydrogen-solar panel

Researchers from three German Fraunhofer Institutes claim to have jointly developed “a tandem module that is self-sufficient and reliable at producing solar-generated green hydrogen”. It’s a classic electrolyzer –  what typically would be complex and expensive – combined in one ‘cheap’ panel. With 100 square meters of these hydrogen-solar panels, they theoretically could produce 30 kg of hydrogen yearly.

However, Belgian researchers who graduated from Louvain University have a clear lead on the Germans. They use a unique combination of physics and chemistry with solar energy and membranes to draw pure hydrogen directly from the moisture in the air. Their panel—also completely self-sufficient—can produce up to 17 times more hydrogen and is almost ready for commercial production.

Mini electrolyzer

The panel, designed by the Germans, uses solar energy directly to split water using a photoelectrochemical cell. (PEC). Like in a traditional electrolyzer, the module uses the solar panel’s electricity directly to separate the water and release hydrogen on the reverse or cathode side and oxygen on the upper side, the anode side.

Since the process results in hydrogen and oxygen, the structure must be designed to maintain a strict separation between the two elements during generation and beyond.

The experts coat standard commercially available float or plate glass with semiconducting materials on both sides to produce the tandem cell. When the sunlight hits the glass, one side of the module absorbs the short-wavelength light. At the same time, the long-wavelength light passes through the upper layer of glass and is absorbed on the reverse side.

Limit in efficiency

“But there is a limit as the panel is most efficient with an active surface area of half a square meter. “In terms of the dimensions of the tandem cell, we are limited by the fact that our module splits the water directly, but it is also necessary for electricity to get from one side to the other to achieve this,” Dr. Arno Görnnotes of the Fraunhofer Institute for Ceramic Technologies and Systems IKTS explains in the press release.

“As the module area increases, the rising resistance has an unfavorable effect on the system. As things currently stand, the existing format has proven to be optimum. It is stable, robust, and significantly larger than any comparable solution.”

Enough for 20,000 km?

The Germans say a single module exposed to sunlight under European conditions can generate over 30 kilograms of hydrogen per year over 100 square meters. “With this yield, a hydrogen car could travel 15,000 to 20,000 kilometers, for example.” But doesn’t that sound over-optimistic, as a typical hydrogen car like a Toyota Mirai already needs 5 kg of hydrogen for a 575 km (EPA) range?

Belgian start-up Solhyd, the spin-off of KU Leuven University created by the researchers that developed the hydrogen panel, announced already in December 2023 securing six million euros of seed capital from ‘a group of experienced entrepreneurs’ to optimize further the basic technology of ‘distilling’ pure hydrogen directly from the air using a particular solar-H2 panel and deploy it in pilot applications.

More complex approach

Their panel—now already cast in an industrial design—is 1.6 square meters and can generate up to 250 liters of hydrogen per day from the moisture in the air, just using solar energy. That’s 0.023 kg of H2 (at 1 atm air pressure) per day for one panel, or 524.6 kg yearly, assuming you combine panels up to 100 square meters and could generate that amount of hydrogen every day of the year.

Jan Rongé is the CEO of Belgian Solhyd and one of the bioscience engineers who developed the hydrogen panel during their doctoral research at KU Leuven. Asked by Newmobility. news, he says the German approach is “a more complex approach, which still has a long way to go. Maybe this can have an impact towards 2040, but with Solhyd, we didn’t want to wait for that: we don’t have that time anymore.”

“We make more than ten times more hydrogen per surface area while using no rare materials. Moreover, our technology is much cheaper to produce,” he adds.