Underwater solar cells can operate 10 meters below the ocean's surface - Energy & Green Tech - Hi Tech & Innovation

The schematic diagram of submerged perovskite solar cells for underwater applications. Credit: Simin Ma, Yunnan University

Scientists have taken solar cells to new depths, demonstrating that they can function 10 meters (33 feet) below the surface of the South China Sea. The study, published Sept. 11 in the journal Joule, found that solar cells could generate 324 milliwatt-hours of electricity during two hours of underwater illumination and could operate continuously at a depth of 10 meters (33 feet) for about 5.5 years. The findings suggest that underwater solar cells may be able to power submerged sensors, cameras and communication systems far from land.

"Very few studies have been reported on underwater solar cells, and all of them are focused on very shallow water depths of only two meters or less, a scenario far from meeting the requirements of practical applications," says study author Wen-Hua Zhang of Yunnan University and Southwest United Graduate School in Kunming, China.

"This work presents the first functional validation of submerged solar cells practically operating at a water depth of up to about 10 meters, greatly broadening their application scope."

Simulating light below the surface

While solar cells have long provided energy to power technologies on land, researchers have struggled to harvest solar energy underwater for monitoring aquaculture and other uses because sunlight quickly drops in intensity over short distances. To overcome this hurdle, Zhang's team first developed a customized laboratory system with tailored optical filters to simulate underwater illumination at various depths.

During laboratory experiments, the researchers determined that the submerged solar cells they developed were among the most efficient, with wide bandgaps, a feature that allows them to absorb blue-to-orange light. After storing the cells in a glove box filled with nitrogen gas for 300 days, the solar cells retained about 96% of their initial efficiency. They also showed almost no degradation after 1,160 hours under simulated conditions at a depth of 10 meters (33 feet), suggesting exceptional durability underwater.

From lab modules to sea trials

Next, the team integrated perovskite solar cells with underwater robots, deploying them at a depth of 10 meters (33 feet) off the Weizhou Islands in the South China Sea to test their real-world applications. The cells exhibited "exceptional" long-term operational stability, Zhang says.

"What surprised us most was how much electrical energy our large-area modules generated under real-world conditions at a water depth of 10 meters for only two hours," Zhang says.

"Moreover, we have achieved scaling from small-area laboratory cells to large-size modules," Zhang says. "The combination of the laboratory investigations and the field experiments provides strong evidence for the operation of underwater photovoltaics."

In future research, Zhang's team plans to test perovskite solar cells at deeper water depths, investigate the limit at which underwater solar cells can operate and establish standardized testing protocols for underwater photovoltaics.

Provided by Cell Press 

by Cell Press

edited by Gaby Clark, reviewed by Robert Egan 

Source: Underwater solar cells can operate 10 meters below the ocean's surface