Underwater solar cells achieve operational stability 30 feet below the surface

Researchers at Yunnan University and Southwest United Graduate School have demonstrated functional underwater solar cells operating at a depth of 10 meters (33 feet) in the South China Sea. The achievement smashes previous limits. Earlier attempts to harvest solar energy underwater stalled out in shallow waters under two meters deep, where sunlight is still plentiful but practical applications are scarce. Combined with an estimated continuous operational lifespan of roughly 5.5 years, this technology could ultimately offer a reliable, long-term power source for remote oceanic systems. The study shows that submerged photovoltaics can provide a viable power source for underwater sensors, cameras, and communication systems in the future. “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 catering for requirements of practical application,” said Wen-Hua Zhang, the study author. “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,” Zhang added. Bandgap optimization Standard commercial silicon solar cells are designed to capture broad terrestrial sunlight, particularly red/infrared rays. Underwater, silicon cells lose most of their efficiency. Typically, submerged solar cells struggle to harvest energy due to the rapid loss of sunlight intensity underwater, posing a hurdle for marine monitoring applications like aquaculture. To address this, Zhang’s team designed wide-bandgap solar cells optimized to capture the blue-to-orange light wavelengths that penetrate ocean waters best. By capturing ambient light beneath the waves, underwater solar cells present a transformative solution to the long-standing power limitations of marine technology. Generating 324 mWh of electricity in just two hours at a depth of 10 meters, these cells produce sufficient energy to recharge standard lithium-ion batteries. Submerged solar cells provide a self-sustaining power source for environmental sensors, monitoring cameras, and communication hardware far from the coastline, doing away with costly wired connections and constant battery replacements. The schematic diagram of submerged perovskite solar cells for underwater applications. Credit: Simin Ma, Yunnan University Shows promise in testing Tested under simulated conditions, these specialized cells proved exceptionally durable, retaining roughly 96 percent of their efficiency after 300 days of storage. Plus, the prototype cells showed almost zero degradation over 1,160 hours at a simulated depth of 10 meters off the Weizhou Islands in the South China Sea. “What surprised us most was so much electrical energy our large-area modules generated under real-world conditions at 10-meter water depth for only two hours,” noted Zhang. “Moreover, we have achieved scaling from small‑area laboratory cells to large‑size modules. The combination of the laboratory investigations and the in-field experiments provides strong evidence for the operation of underwater photovoltaics,” said Zhang. Among the future challenges, these cells must pair high durability with crystal-clear light transmission to remain effective for long durations. Also, underwater solar deployment requires overcoming extreme conditions such as corrosive salt, high pressure, and water ingress. Next, the team plans to push deeper into the dark, testing how far down solar technology can go while laying the groundwork for standardized testing protocols for underwater photovoltaics. The study was published in the journal Joule. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Mrigakshi is a science journalist who enjoys writing about space exploration, biology, and technological innovations. Her work has been featured in well-known publications including Nature India, Supercluster, The Weather Channel and Astronomy magazine. If you have pitches in mind, please do not hesitate to email her.