Solar power is moving beyond rooftops and open land. Researchers have successfully tested perovskite solar panels 10 metres beneath the South China Sea, raising the possibility of longer-lasting power for ocean sensors, cameras and other underwater equipment.
The experiment, conducted near the Weizhou Islands off southern China, produced electricity during a two-hour trial. The findings, published in the science journal Joule, suggest that specially designed solar cells could operate underwater for years, although further testing is needed before the technology can be used commercially.
How underwater solar panels generate electricity
Water rapidly absorbs and scatters sunlight, meaning only a fraction of the energy available at the surface reaches deeper areas. At 10 metres, much of the visible spectrum has already been weakened, but blue and green wavelengths can still travel through seawater.
The research team used perovskite solar cells rather than conventional silicon panels. Perovskites are materials whose light-absorbing properties can be adjusted, allowing engineers to design cells for the wavelengths that remain available underwater.
In laboratory simulations replicating conditions at a depth of 10 metres, the cells converted about 35% of the sunlight reaching them into electricity. That performance provided the basis for the larger field test in the South China Sea.
Results from the sea trial
The researchers tested panels with an area of 115 square centimetres at two different depths. At two metres, the panels generated 1,416 milliwatt-hours over two hours. At 10 metres, they produced 324 milliwatt-hours during the same period.
The output at 10 metres was considerably lower, but it demonstrated that the panels could still generate usable power where sunlight is severely limited. The researchers also reported almost no performance loss after 1,160 hours in simulated underwater conditions.
Based on those laboratory tests, the team estimates that the perovskite solar cells could operate continuously at 10 metres for approximately five and a half years. That is an estimate rather than a confirmed operating lifetime in the open sea.
Why underwater solar power matters
Underwater equipment often operates far from shore-based electricity supplies. Oceanographic sensors, monitoring cameras and communication systems may depend on batteries, which eventually require replacement or retrieval missions.
A compact source of renewable electricity could extend the operating life of such equipment and reduce the need for maintenance trips. Potential applications could include:
- Environmental monitoring sensors;
- Underwater cameras and observation systems;
- Oceanographic research instruments;
- Communication and navigation equipment; and
- Remote systems that need more power than batteries can reliably provide.
The technology would not replace large solar farms or conventional offshore energy systems. Its likely value lies in supplying modest amounts of electricity directly to equipment located beneath the surface.
Underwater solar panels build on wider off-grid innovation
The experiment forms part of a broader trend in which solar technology is being adapted for locations where grid electricity or fuel supplies are difficult to access.
Solar systems have already been developed for remote healthcare, isolated infrastructure and transport sites. Examples include solar-powered vehicles intended for rural medical services, renewable generation at remote sites in Norway’s Svalbard archipelago and panels installed between railway tracks in Switzerland.
Underwater solar power addresses a different challenge: keeping equipment operating in an environment where access is difficult and battery replacement can be expensive or disruptive.
What researchers need to test next
The South China Sea trial lasted two hours, while the longer durability evidence came from laboratory simulations. That means the research does not yet demonstrate that the panels can withstand years of exposure to every condition found offshore.
Further work will need to examine how the cells perform:
- At depths greater than 10 metres;
- In changing water clarity and weather conditions;
- During long-term exposure to saltwater and marine growth;
- Under movement caused by waves and currents; and
- When connected to real underwater equipment.
The researchers say their next step is to establish how far beneath the surface solar generation remains practical. That will help determine whether the technology is best suited to shallow coastal waters or could eventually support equipment at significantly greater depths.
Conclusion
The underwater solar panels tested by researchers show that sunlight can still produce electricity 10 metres below the sea when solar cells are designed for the wavelengths that penetrate seawater. The current output is modest, but the potential five-and-a-half-year operating estimate could make the technology useful for remote sensors and communications equipment. More open-water and deeper-sea testing will determine whether this promising research can become a dependable part of future ocean infrastructure.
