Perovskite solar cells tested 10m underwater charge batteries — NRG-IA

A perovskite solar module has generated electricity 10 meters below the sea surface and charged lithium-ion batteries in a test conducted in the South China Sea. The module had an active area of 115 cm² and accumulated 324 mWh of energy in two hours at this depth, demonstrating that photovoltaics can be designed for environments where light is much weaker and has a radically different spectral composition than at the surface. The result, published on September 11, 2026, in the journal Joule , does not open up the prospect of underwater solar farms powering cities. Instead, it unlocks a much closer and more realistic application: powering sensors, cameras, communication equipment, and other devices that must operate autonomously underwater, where every maintenance intervention translates into extra time, logistics, and costs. The cell was designed for the light that survives underwater At the surface, a solar panel receives a broad spectrum of radiation. Underwater, the situation changes rapidly. Water strongly absorbs longer wavelengths, including much of the red and infrared radiation, and at depths of about 5–10 meters, the available light is dominated by the blue-green region, roughly between 400 and 600 nanometers. This is one of the reasons why a conventional silicon panel is not the ideal choice for such conditions. A significant portion of the spectrum that silicon can utilize at the surface disappears as light travels through water. Research published in Nature Photonics had already identified this spectral mismatch as a major challenge for underwater photovoltaics and pointed to wider-bandgap materials, including perovskites, as promising candidates. The team behind the new study engineered a perovskite with a bandgap of approximately 1.96 eV , tailored to the remaining solar spectrum at these depths. The properties of perovskites can be tuned by altering the material's composition, allowing the cell to be optimized for specific wavelengths. In practice, the researchers did not try to make a terrestrial panel work underwater. They designed the cell for the light that actually remains there . At 10 meters, the module successfully charged a battery The field test shows how rapidly the solar resource declines as the module descends. In two hours of natural exposure, the 115 cm² modules charged the batteries with 1,416 mWh at 2 meters , 752 mWh at 6 meters , and 324 mWh at 10 meters . At the maximum depth, the energy harvested was about 23% of that collected at 2 meters during the same interval. The figure of 324 mWh seems minuscule compared to the energy produced by panels installed on a house or in a solar farm. For a low-power underwater system, however, the relevant comparison is different: can the device continuously harvest enough energy to extend its autonomy or recharge its battery without being pulled out of the water? The experiment shows that the answer can be affirmative for certain tasks. The researchers charged lithium-ion batteries and powered LEDs, and the study points to underwater sensors, cameras, and communication systems as potential applications. This is where the real economic advantage lies. For a sensor installed in a hard-to-reach area, the energy does not necessarily need to be abundant; it needs to be available consistently enough to reduce reliance on retrieving the device, changing the battery, or powering it via a dedicated cable. The 34.71% efficiency shows how well the cell utilizes the remaining light The most spectacular value in the study appears in the laboratory: a 34.71% conversion efficiency when the cell was illuminated with a spectrum designed to replicate conditions at approximately 10 meters underwater. Under standard AM 1.5G solar conditions, the same family of devices achieved 17.08% and 16.79% certified efficiency , respectively. However, these two percentages measure performance under different spectra. The 34.71% figure shows that the device converts the light actually reaching the cell at that depth highly efficiently. It does not mean that 34.71% of the solar energy available at the surface is present at 10 meters, nor that an underwater module can produce the same power as one in full sunlight. Absolute power remains limited by the dwindling amount of light available at depth. This is precisely why the natural application of this technology is not utility-scale energy production, but powering low-demand devices. A self-charging sensor could change the economics of underwater monitoring Much of the world's oceans are difficult and expensive to monitor continuously. Underwater sensors and instruments rely on batteries, power cables, or periodic retrieval for maintenance. A local photovoltaic source could top up the battery during the day and extend the period a device can operate autonomously. For marine environmental monitoring, oceanographic equipment, cameras, or communication systems, this practical advantage can be far more important than the…