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Research Promises Full-Spectrum Solar Cell
nphillips writes "As is being here reported here, a serendipitous discovery was made that a single system of alloys incorporating indium, gallium, and nitrogen can convert virtually the full spectrum of sunlight -- from the near infrared to the far ultraviolet -- to electrical current. For if solar cells can be made with this alloy, they promise to be rugged, relatively inexpensive -- and the most efficient ever created. Solar cells so efficient and so relatively cheap could revolutionize the use of solar power not just in space but on Earth."
As I understand it, UV light hits the earth at all hours.
Does anyone know how much UV hits the earth during the night?
Almost none. Virtually all of the light that strikes Earth comes from the sun.
As another poster pointed out, you may be confusing this with the mid-IR glow that warm objects (including the ground and the air) give off. The amounts of energy involved are very low, and room-temperature thermal IR is difficult to convert to electricity efficiently.
Any solar power scheme (and so any photovoltaic scheme) has to have enough storage capacity to power the load overnight. Ideally, it should be able to provide power for several days, in case of cloud cover/rain/whatever. This is why most home-powering schemes involve large battery arrays. A city-powering solar plant would probably use fuel cells (energy density is much higher, and there are off-the-shelf models of power-plant scale already available and in use).