Swiss and Chinese Scientists Develop Solar Panels That Generate Power Underwater
The perovskite-based cells produced electricity at a depth of ten meters in the South China Sea. Researchers say the technology could power sensors, cameras, and underwater robots without cables or battery replacements.
Solar panels are no longer confined to rooftops. They line roads, float on alpine lakes, and sit between railway tracks. Now they may be heading somewhere entirely new: beneath the surface of the sea.
Researchers at Yunnan University in China, working with a team from the Swiss federal technology institute ETH Lausanne, have developed solar cells capable of generating electricity underwater at a depth of ten meters. The ETH group was led by Michael Grätzel, one of the world's foremost researchers in photovoltaics. The work was published in the journal Joule.
Producing solar energy underwater is far from simple. The deeper the water, the more it absorbs solar radiation, and the spectrum of light changes with depth. The researchers solved this by using a material that mimics the behaviour of a crystalline mineral called perovskite. This allowed them to exploit the wavelengths that can still penetrate to such depths.
Perovskite is originally a natural mineral based on calcium titanate. In photovoltaics, the term refers to synthetic materials that imitate its crystal structure. Their composition can be altered to absorb specific parts of the light spectrum, making them particularly versatile for solar cells.
In the laboratory, the cells achieved an efficiency of nearly 35 percent under light equivalent to that found at a depth of ten meters. That is a very high value, though it cannot be directly compared with the efficiency of normal solar panels under sunlight, since the spectrum and intensity of the light used are different.
The research went beyond simulations. The modules were also tested under real conditions in the South China Sea and demonstrated that they can generate electricity underwater. A large module illuminated for two hours at a depth of ten meters produced 324 milliwatt-hours of energy, which was used to charge lithium-ion batteries and power LEDs.
Durability is also promising. In accelerated tests, the cells showed very low degradation. The researchers estimate a T80 value — the time in which performance drops to 80 percent of its initial value — of approximately 48,000 hours, equivalent to 5.5 years under simulated conditions at ten meters depth.
The technology could be used to make sensors, cameras, underwater robots, communication systems, and aquaculture monitoring equipment energy self-sufficient. These are devices that today often require regular battery replacements or long cables connected to the surface.
For now, the panels are a laboratory success with promising field tests behind them. The question is whether they can be scaled, deployed, and maintained in the harsh environment of the open ocean. But the potential is enormous. If solar power can work beneath the waves, the number of places where clean energy can be generated expands dramatically. The sea, it turns out, may be the next frontier for photovoltaics.
Written by Sandy van Dongen sandy.vandongen@alpineweekly.com