Scientists at the U.S. Naval Research Laboratory have uncovered something of a breakthrough that could help us harness underwater solar energy more effectively than what's been possible to this point. Traditionally employing solar technology underwater has proven difficult since water happens to absorb a key ingredient: sunlight. Researchers have also largely stuck to solar cells that depend on unobstructed spectrum from the sun, which isn't exactly a recipe for success when those cells are submerged and taking in far less solar radiation.
But recent discoveries at the NRL's Electronics Science and Technology Division note that energy conversion can be improved if solar cells are specifically attuned to the narrow spectral ranges that travel underwater. Gallium indium phosphide cells fit the bill in that regard, offering high efficiency at wavelengths between 400 and 700 nanometers — precisely what you'd find below the surface. Early tests show output levels that reach seven watts per square meter at depths up to 9.1 meters, or roughly 30 feet. For now, the tech is aimed at powering underwater autonomous systems and sensor platforms, but there's no telling where these advancements will ultimately lead.