German scientists have developed a new device for converting solar energy into hydrogen fuel in a much more effective and efficient manner than before.

Using a solar cell and a photo anode made of a metal oxide, scientists have successfully stored nearly five percent of incoming solar energy in the form of hydrogen. The design of the new solar cell is much simpler than the traditional techniques, usually employing high-efficiency triple-junction cells based on amorphous silicon or expensive III-V semiconductors.

“Basically, we combined the best of both worlds,” says Prof. Dr. Roel van de Krol, head of the HZB Institute for Solar Fuels, “we start with a chemically stable, low cost metal oxide, add a really good but simple silicon-based thin film solar cell, and viola; we've just created a cost-effective, highly stable, and highly efficient solar fuel device."

The process (known as artificial photosynthesis), allows solar energy to be stored in the form of hydrogen which can then be used as a fuel directly, in the form of methane, or in a fuel cell. Rough estimates say 100 square meters of this type of system is theoretically capable of storing 3 kilowatt hours of energy in the form of hydrogen in just one single hour of sunshine. The stored energy could then be available at night or on cloudy days.

The break-through research could help propel solar energy forward as an effective and renewable source by removing the aspects that can lead to inconsistent power supplies and criticisms of instability.

The research has been published in the journal Nature.