Yunnan University Team in China Validates Underwater Solar Cells at 10-Meter Depth in the South China Sea

en.Wedoany.com Reported - Researchers from Yunnan University and the Southwest United Graduate School have demonstrated a functional underwater solar cell capable of operating at a depth of 10 meters (33 feet) in the South China Sea, completing functional validation during actual operation at approximately 10 meters. The technology is expected to have a continuous operating life of about 5.5 years, offering the potential to provide reliable, long-term power for remote marine systems; the study indicates that underwater photovoltaics could in the future provide a viable power source for underwater sensors, cameras, and communication systems.

This achievement breaks previous limits. Earlier attempts at underwater solar energy harvesting stopped at shallow waters less than two meters deep, where sunlight is still abundant but practical applications are scarce. Study author Wen-Hua Zhang said that research reports on underwater solar cells are extremely few and all focus on extremely shallow waters of only two meters or less, a situation far from meeting practical application needs; this work provides the first functional validation of underwater solar cells operating at a depth of approximately 10 meters, broadening their range of applications.

Standard commercial silicon solar cells are designed to capture broad terrestrial sunlight, especially red/infrared light, but lose most of their efficiency underwater. Underwater sunlight intensity attenuates rapidly, making it difficult for underwater solar cells to harvest energy and creating obstacles for marine monitoring applications such as aquaculture. Zhang's team therefore designed wide-bandgap solar cells optimized to capture blue to orange wavelengths, which penetrate seawater most effectively. By harvesting ambient light beneath the waves, underwater solar cells offer a solution to the long-standing power supply limitations of marine technology.

At a depth of 10 meters, these cells generated 324 milliwatt-hours (mWh) in just two hours, enough to charge a standard lithium-ion battery. The cells can provide self-sustaining power for environmental sensors, surveillance cameras, and communication hardware far from the coastline, eliminating the need for expensive cable connections and frequent battery replacements.

When tested under simulated conditions, these specialized cells demonstrated durability: they retained approximately 96% efficiency after 300 days of storage. The prototype cells operated for 1,160 hours at a simulated depth of 10 meters near Weizhou Island in the South China Sea with almost no degradation. Zhang noted that what surprised the team most was that a large-area module generated so much electricity in just two hours under real conditions at a depth of 10 meters. He also said the team achieved scaling up from small-area laboratory cells to large modules; combining laboratory research with field experiments provides strong evidence for underwater photovoltaic operation.

Subsequent applications still face challenges: the cells must combine high durability and clear light transmission to remain effective over the long term; underwater solar deployment must also overcome extreme conditions such as corrosive salt, high pressure, and water ingress. Next, the team plans to advance to deeper, darker waters to test how deep solar technology can go, while laying the foundation for standardized testing protocols for underwater photovoltaics.

The study was published in the journal Joule.