xxxxx
Hazard to Others
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Registered: 21-5-2004
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increase light input to solar cells
i had heard that orbiting space stations use solar cells to produce electricity and that above the earth's atmosphere sunlight is 10 times as intense
as at sea level. i was wondering if a thin plastic fresnel lens could be used to increase the intensity of light entering a solar cell at sea level
and if so how many times normal sunlight intensity could conventional solar cells accept without some type of damage or failure and would electrical
output increase linearly.
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12AX7
Post Harlot
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Your brief wording implies laminating a fresnel right over the panel. This is useless, because it saves no area. The fresnel needs to be at a
distance (some ratio of the focal length) to concentrate the light onto the panel's economically limited area.
I don't know what the limits are for power output. Probably, cells become less efficient and last shorter when intense light is directed on them. I
don't know if there is a saturation where more light causes very little additional electrical output. The panels must be oriented to gather enough
light, since the response becomes very directional, instead of merely the sine of the angle beteen the panel and the sun, which can stand wide
variation. You at least have the opportunity to block harmful UV radiation with a suitable coating, and a modicum of armor against micrometeorites by
the lens' thickness.
Tim
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Twospoons
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The problem is getting rid of the waste heat. Efficiency of PV cells drops as they get hot. It is quite feasible, however, to use reflectors for a
2:1 or 3:1 concentration ratio. The other point is that lenses work well for point light sources (like the sun) but fair poorly under diffuse light
conditions (cloud cover). Google "compound parabolic reflector" for a good diffuse light collector design.
Helicopter: "helico" -> spiral, "pter" -> with wings
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phase_dancer
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I was quite impressed with this guy's earlier designs, as they were featured on Australian television a couple of years ago.
http://www.abc.net.au/tv/newinventors/txt/s1487858.htm
http://www.greenandgoldenergy.com.au/
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