Is the idea of using solar energy in underwater exploration viable?

At first glance, the idea may not seem promising. After all, how much solar energy can penetrate through the thickness of water? It is well known that eternal darkness reigns at depth. Nevertheless, researchers from Tandon University in New York have been considering the prospects of photovoltaics in exploring the world's oceans using autonomous and remotely operated underwater robots. Source: Nature Photonic https://doi.org/10.1038/s41566-023-01276-z 

Underwater robots are an excellent tool for scientists to conduct various underwater explorations. However, the autonomy of robots is limited by the need for constant recharging. Often, onboard power sources are not installed on remotely operated vehicles, forcing them to rely on power supplied through cables from accompanying vessels.

The Tandon researchers are considering creating alternative power systems for autonomous and remotely operated underwater vehicles that would allow them to surface less frequently for recharging. Moreover, underwater power sources would also be useful for underwater sensors, navigation, and communication systems, reducing their dependence on battery resources or eliminating the need to run power cables to them.

Research has shown that using waves, tides, and currents for underwater exploration has potential, but their effectiveness depends on location and can limit mobility. Thermal energy from the ocean and temperature gradients are also options, but they have limited potential for stationary underwater devices. However, sunlight has potential as visible light can penetrate up to 50 meters deep, providing energy for recharging underwater robots and electronic devices. 

One issue with using photovoltaic cells underwater is that common ones are optimized for red and infrared light, reducing their efficiency underwater. Alternative options such as gallium indium phosphide (GaInP) and cadmium telluride (CdTe) panels show higher efficiency in ocean conditions, as well as organic (OSC) and perovskite cells. 

Biofouling is another issue as research has shown that after just 30 days, over 50% of the absorbing surface of underwater panels is affected, reducing their efficiency. This problem is more significant in tropical waters but becomes less of an issue at higher latitudes, making the idea viable in Arctic waters. 

While a final answer to the question of using solar energy in underwater exploration is premature, the idea of using photovoltaics to create underwater solar power stations may be worth further investigation.  \\