Researchers Develop a Strategy for Underwater Solar Power

Some of the greatest innovations in the field of clean energy are coming from solar power. Now, a team of researchers from Yunnan University in China have taken it to a new level—below sea level, in fact. While the idea is not entirely new, the scientists have made it work at 33 feet deep, breaking a record in photovoltaic research and widening the possibilities for this natural resource.

In a new study published in Joule, the researchers shared their findings on perovskite-based solar cells, which is a type of semiconductor crystal. This allowed them to tweak the panels to capture the blue and green wavelengths of sunlight that make it through the ocean surface.

The team also mixed in a polymer called polyhexamethylene guanidine hydrochloride, which captures even more electrons, and added a water-repelling layer to delay water-induced degradation of the equipment. With this, the solar cells could operate for up to five and a half years.

“Very few studies have been reported on underwater solar cells, and all of them are focused on very shallow water depths of only 2 meters or less, a scenario far from catering for requirements of practical application,” professor Wen-Hua Zhang told Science Alert. “This work presents the first functional validation of submerged solar cells practically operating at a water depth of up to about 10 meters, greatly broadening their application scope.”

First, they tested their solar cells in a lab simulating illumination at 10 meters under the sea. There, they reached a power conversion efficiency—that is, how much sunlight reaching a panel is converted into usable energy—of almost 35%, matching the latest breakthroughs, with the perk of theirs taking place underwater. The mark also surpasses the Shockley-Queisser limit, a theory that caps photovoltaic efficiency at 33%.

The researchers then took the cells to the ocean, submerging them off the coast of Weizhou Island in the South China Sea with remotely operated robots, where they tested them at three different depths for two hours. At 2 meters (6.5 feet), the cells harnessed 1,416 milliwatt-hours (mWh) of electricity; at 6 meters (19.6 feet), they got 752 mWh; and at 10 meters (32.8 feet), they collected 324 mWh—enough to power a small LED light for a few hours.

While a commercial application of these underwater solar cells won’t come any time soon, it could definitely become a reliable source of energy for a variety of academic and technology resources, including anything from a camera providing a livestream to smart sensor networks. The study authors say, “This work paves the way for the practical deployment of perovskite photovoltaics in underwater environments, offering a promising route toward self-sustained marine energy systems and autonomous underwater devices.”