Researchers in China have taken a notable step in underwater solar energy, testing solar modules 10 meters below the surface in the South China Sea near Weizhou Island. After two hours underwater, the system stored 324 milliwatt-hours of energy in lithium-ion batteries, enough to later power an LED panel.
The team designed the cells around the light that survives at depth. Since water absorbs red and infrared wavelengths quickly, the underwater spectrum is dominated by blue-green light. To match that environment, the researchers used a wide-band-gap perovskite material with a band gap of about 1.96 electron volts, supported by a polymer additive that improved crystal quality and reduced defects.
In laboratory simulations of 10-meter-deep conditions, the small cells converted 34.71% of incoming light into electricity, while larger modules reached 29.4% underwater. Under normal sunlight, the same cells achieved 17.08%, showing that the design is tuned for the underwater spectrum rather than surface use.
Wen-Hua Zhang of Yunnan University, the study's senior author, said the approach could help extend the operating time of marine devices by offering a continuous power source. The researchers also noted that deeper deployment may be possible, with early estimates suggesting practical use at 20 to 30 meters in the future.
Challenges remain, including biofouling, debris, and seawater corrosion, but the project points to a new path for powering autonomous underwater vehicles and other smart ocean systems. Published in Joule, the study suggests that marine energy design may soon expand from the surface into deeper waters, shaping the next generation of underwater technology.
