Science does not stand still, and alternative energy sources wherever they are mounted and what is just is not used. But there are places on this earth where it is particularly difficult to produce energy. For example: the ocean. For such purposes the U.S. Navy developed solar panels that can produce energy at a depth of 9 meters!
In the Research Laboratory of the U.S. Navy developed solar panels with a wide band gap. Such batteries are best suited for efficient production of sufficient energy for electronic sensor systems to a depth of 9 meters.
Underwater autonomous systems and sensor platforms are severely limited in use because of the lack of a long-lived source of energy. At present, all of them are powered by sources located on the coast or on the platform above the water.
Attempts to use traditional solar not over, and under water were unsuccessful due to lack of sunlight, because such batteries are adapted to work with conventional, terrestrial spectrum. And, according to scientists, although the water and absorbs sunlight, the main technical challenge is to develop a battery that would effectively convert the remaining "hidden" photons into electricity.
Although the absolute intensity of solar radiation by water below, the spectral composition of the remaining narrow stream of photons, which should contribute to the high conversion efficiency of the battery, "incarcerated" under the spectrum of the incident on her wavelength.
Researchers have found that for the water quality are most suitable cell based on gallium indium phosphide (GaInP). They have a high quantum efficiency for photons with a wavelength of between 400 and 700 nm (visible light) and low current shadow, which is critical for high performance in low light conditions.
The spectrum of sunlight in the underwater world is confined primarily to the waves of blue and green area, but because photovoltaic cells with a large band gap, and what are the batteries are at GaInP, are significantly better than traditional silicon.
Preliminary tests at a depth of 9.1 meters showed the output power of 7 W / m? solar battery. It is a little, but for those tasks that are put before the batteries should last. Another minus — the high price of indium.
On materials: computerra.ru