Navy Puts Solar Cells Nine Meters Under WaterCategory: Science & Technology
Posted: June 11, 2012 11:09AM
Getting power or an Internet connection in some parts of the country can be difficult, because the area is so far removed from the nearest ISP or power plant. At least it is still possible to run a cable over or under ground to transmit whatever is needed. In the ocean though, cable installation is not exactly viable. For this reason the Naval Research Laboratory has been working on specialized solar cells for electronic sensors that operate under water. In this case, about nine meters below the surface.
As you may expect, just putting a solar panel under water does not work very well because the water blocks a lot of the light. As it turns out though this blocking of light can be an advantage. Surface solar panels have a wide spectrum of light to work with, and the more frequencies it can absorb, the more electricity it can produce. Water filters out many frequencies, leaving primarily green and blue, so the underwater solar panels can be designed to respond specifically to this smaller frequency range.
The researchers moved away from silicon for their new panels and instead used high-quality gallium indium phosphide (GaInP) for the cells. This material has a higher bandgap, which means it reacts better to higher frequencies of light, including the frequencies from green to blue. The preliminary tests of the new cell achieved an output of 7 W at a depth of 9.1 m. Seven watts may not seem like much, and it probably isn't for what the NRL will ultimately want from underwater solar cells, but it is enough to show there is power down there.