A team of Chinese and Swiss researchers has demonstrated solar cells capable of generating electricity at a depth of around 10 metres underwater potentially opening new possibilities for powering submerged sensors, cameras aquaculture monitoring systems and offshore communications equipment.
Published in the journal joule the study addresses a major challenge for underwater solar power: sunlight is rapidly weakened and its spectrum changes as it passes through water. Conventional solar cells have generally been tested only at very shallow depths of around two metres.
The researchers developed lead-halide perovskite solar cells whose light absorption is matched to the spectrum available underwater at greater depths. Laboratory experiments showed that the cells could effectively absorb blue to orange wavelengths that penetrate the water.
The technology also demonstrated promising durability. After being stored in an oxygen-free environment for 300 days, the solar cells retained about 96% of their initial efficiency. Under simulated conditions equivalent to a 10-metre depth, they showed almost no degradation after 1,160 hours of testing.
The researchers then moved beyond laboratory experiments and tested larger solar modules on underwater robots near the Weizhou Islands in the South China Sea. At a depth of 10 metres, the modules demonstrated stable operation under real-world marine conditions.
According to researcher Wen Hua Zhang of Yunnan University and Southwest United Graduate School, the experiments also showed that the technology could be scaled from small laboratory cells to larger modules.
The researchers are now planning tests at greater depths to determine how far underwater photovoltaic systems can operate effectively. They also aim to establish standardised testing methods for underwater solar cells.
Unlike conventional solar farms, the proposed technology is not primarily intended for large scale electricity generation. Its potential applications include supplying power to underwater monitoring equipment, aquaculture systems and offshore communication infrastructure, reducing the need for batteries or frequent maintenance missions.
The findings suggest that sunlight could potentially become a practical power source not only on land and at the water’s surface, but also for selected underwater technologies.