Sunlight fades quickly once it enters seawater. Red and infrared wavelengths disappear within the first few metres, leaving a dim blue-green glow at greater depths. Conventional silicon solar panels, optimised for the full terrestrial spectrum, become almost useless there. Yet researchers have now demonstrated that specially engineered solar cells can generate usable electricity ten metres beneath the surface. The reason is practical: a growing number of underwater devices need power far from shore, and batteries alone limit how long they can operate.
The Physics Problem and the Engineering Answer
Water is an effective filter. By roughly five to ten metres, the light that remains is concentrated in the blue-green range, roughly 400 to 600 nanometres. A standard solar cell wastes much of its capacity on wavelengths that never arrive. The solution is to design a cell whose absorption matches the light that does reach that depth.
A team from Yunnan University in China used wide-band-gap lead-halide perovskite cells tuned to that narrower spectrum. In laboratory conditions simulating ten-metre depth, the cells converted about 35 percent of the available light into electricity. That is a higher conversion efficiency of the light that is present than the same cells achieve under full terrestrial sunlight, even though the absolute power is far lower because far less light arrives.
The cells were protected with glass, synthetic rubber and epoxy to withstand seawater. Accelerated ageing tests suggested a useful lifetime of roughly five and a half years under continuous submerged conditions at typical sea temperatures before output would fall to 80 percent of its starting value.
Real-World Test Results
The researchers took the modules into the South China Sea near the Weizhou Islands and mounted them on a small underwater vehicle that held a fixed depth. Over two-hour tests they recorded:
- 1,416 milliwatt-hours at two metres
- 752 milliwatt-hours at six metres
- 324 milliwatt-hours at ten metres
The energy collected at ten metres was enough to charge lithium-ion coin cells that later powered an LED display. Performance at two metres fluctuated with surface waves; at greater depth the light was dimmer but more stable because of increased scattering.
This appears to be the first clear demonstration of functional solar generation at a full ten-metre operating depth, moving the concept beyond earlier experiments limited to roughly two metres or less.
Why Bother? Practical Uses
The motivation is straightforward. Large parts of the ocean and many coastal and aquaculture sites lack easy access to surface power or frequent battery replacement. Devices that could benefit include:
- Autonomous underwater vehicles and robots that need extended range or endurance without surfacing to recharge
- Stationary sensors and cameras for environmental monitoring, reef health, or security
- Communication nodes and data loggers on the seabed or mid-water
- Equipment supporting fish farms and other aquaculture operations
- Scientific instruments deployed for long periods in remote locations
In each case the alternative is either frequent retrieval for battery changes, expensive cabling from the surface, or acceptance of short mission times. A submerged solar source that works for several years could reduce those constraints.
Cooling by the surrounding water and the absence of ultraviolet light at depth may also help the cells last longer than equivalent perovskites on land, where heat and UV accelerate degradation.
Limitations and Realistic Expectations
The absolute power output remains modest. Three hundred and twenty-four milliwatt-hours in two hours at ten metres is useful for low-power electronics, not for high-demand systems. Scaling to larger arrays, ensuring long-term sealing against seawater, biofouling, and mechanical stresses from currents or marine life will all require further engineering. Cost, manufacturing consistency and environmental impact of the materials must also be addressed before widespread deployment.
The technology is therefore best understood as a way to extend the endurance of specific underwater systems rather than as a bulk power source competing with surface solar or offshore wind.
Broader Context
More than 70 percent of Earth’s surface is ocean. Most of that volume has been difficult to instrument continuously because of power limitations. Submerged photovoltaics tuned to the underwater spectrum offer one route to self-powered devices that can remain on station for years. Combined with improvements in low-power electronics and energy storage, they could support denser monitoring networks, longer robotic missions and more persistent data collection in places that are currently under-observed.
The recent sea trials show that the concept works at a depth previously considered impractical for solar generation. The remaining questions are engineering scale-up, durability in real marine conditions, and identification of the applications where the modest but steady power is most valuable.
Would you see this technology as more useful for scientific sensors, underwater vehicles, or commercial aquaculture monitoring? Share your view.
Frequently Asked Questions
Can ordinary solar panels work underwater?
Standard silicon panels lose most of their effectiveness within a few metres because water filters out the wavelengths they are designed to capture. Specially tuned cells are required.
How much power was generated at ten metres?
In the South China Sea tests, the modules produced 324 milliwatt-hours over two hours at ten metres depth, enough to charge small lithium-ion batteries.
How long might these cells last submerged?
Accelerated tests suggested a useful lifetime of about 5.5 years under continuous operation at typical sea temperatures before output drops to 80 percent.
What are the main intended uses?
Powering autonomous underwater vehicles, sensors, cameras, communication systems and aquaculture monitoring equipment that cannot easily be retrieved for battery changes.
Why use perovskite instead of silicon?
Perovskites can be chemically tuned to match the narrow blue-green spectrum that penetrates to five or ten metres, something conventional silicon cells cannot do efficiently.
Is this ready for commercial deployment?
It is still at the research and demonstration stage. Further work is needed on large-scale manufacturing, long-term sealing, biofouling resistance and cost.
Reference links:
https://www.sciencealert.com/scientists-successfully-test-underwater-solar-cells-32-feet-below-the-south-china-sea
https://www.eurekalert.org/news-releases/1142532
https://spectrum.ieee.org/perovskite-underwater-solar-panels
https://arstechnica.com/science/2026/09/a-new-solar-cell-could-generate-electricity-underwater/
https://www.earth.com/science/underwater-solar-panels-could-make-remote-parts-of-the-ocean-easier-to-monitor/
https://www.techspot.com/news/113856-underwater-solar-power-sounds-impossible-new-perovskite-cells.html
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