02 Aug '10 16:27>
http://www.physorg.com/news199962208.html
Potentially 2X the efficiency of regular silicon cells!
Potentially 2X the efficiency of regular silicon cells!
Originally posted by joneverySounds like it would be pretty useless WITHOUT one! It seems to love 200 degrees C or near 400 degrees F. The ones on the space station don't even get that hot.
With increasing efficiency at high temperatures sounds like it would be useful in a concentrator cell.
Originally posted by sonhouseBut mirrors are cheap. It would presumably be fairly easy to set up a tin foil reflector on your roof that concentrates the sunlight onto one of these. The actual area of solar cells could then be even smaller than usual and thus even cheaper for a given amount of sunlight captured.
Sounds like it would be pretty useless WITHOUT one! It seems to love 200 degrees C or near 400 degrees F. The ones on the space station don't even get that hot.
I wonder how close to the sun you would have to go with a space probe to get that temperature on exposed PV cells?
Originally posted by twhiteheadMore than less efficient at higher temps, they deteriorate quickly at those temps. That's why they use gallium arsenide, they can take that kind of heat by design.
But mirrors are cheap. It would presumably be fairly easy to set up a tin foil reflector on your roof that concentrates the sunlight onto one of these. The actual area of solar cells could then be even smaller than usual and thus even cheaper for a given amount of sunlight captured.
Here in Africa we frequently use corrugated galvanized Iron as roofing ...[text shortened]... to save costs on standard solar cells is that they are less efficient at higher temperatures.
Originally posted by sonhouseIf the width is not enough, then larger corrugations would be needed, but that would reduce the strength (which is what the corrugations are for). So that idea might have to be scrapped in favor of a dish shaped roof!
The problem with using a corrugated structure like you are talking about is the small surface area of each corrugation. A couple of cm across but meters long. There would by design have to be a large area of pv cells at each focal line and there would not be enough concentration to get up to 200 C.
Originally posted by twhiteheadSince the sun moves on an east-west path, the trough would have to be oriented north-south. There would have to be some kind of tracking still but only in one dimension, tilting the trough to follow the sun. After a tilting mechanism has been built, it could be just run by hand, move it to a better position after 15 minutes or whatever.
If the width is not enough, then larger corrugations would be needed, but that would reduce the strength (which is what the corrugations are for). So that idea might have to be scrapped in favor of a dish shaped roof!
[b]Did anyone put a temperature probe in in food in the pot on that cooker? I doubt it got up to 200 C.
I do know that they work. Y would work better than a dish, but I could be wrong. Maybe an East-West trough would be better?[/b]
Originally posted by sonhouseI am not convinced. I think that a East to West trough tilted to the angle of the suns arc would loose a little light at the ends, but otherwise remain in focus for most of the day along most of its length.
Since the sun moves on an east-west path, the trough would have to be oriented north-south.
Originally posted by twhiteheadIf you go east-west orientation, it would do like you say but I think the actual concentration would be a lot lower overall. You would get a lot more bang for the buck to go with the north south idea. Flat mirrors certainly work but they would have to be individually aimed, I don't think you would want the job of engineering that.
I am not convinced. I think that a East to West trough tilted to the angle of the suns arc would loose a little light at the ends, but otherwise remain in focus for most of the day along most of its length.
[b]After a tilting mechanism has been built, it could be just run by hand, move it to a better position after 15 minutes or whatever.
Obviousl ...[text shortened]... t the end of the house. Of course the mechanism for tilting the mirrors might get complicated.[/b]
Originally posted by uzlessThat way you can lose half the energy which has been beamed back to Earth and then the system performs exactly as good as the non heat converting cells🙂
should just place solar panels close to the sun and then beam the electricity wirelessly back to earth
Originally posted by uzlessWhat sort of wireless energy beam would you use? Light?
should just place solar panels close to the sun and then beam the electricity wirelessly back to earth
Originally posted by twhiteheadMicrowaves are the energy of choice. It's really the same energy, just a lot lower frequency. The main thing is, the atmosphere is more transparent to UHF radiowaves or microwaves.
What sort of wireless energy beam would you use? Light?
Surely the most efficient would be a large magnifying glass between the earth and the sun rather than pv cells to electricity then back to light.
Or are other beams like microwaves more efficient?
Originally posted by sonhouseWhat are the benefits? You implied earlier that about half the sunlight is lost on entry through the atmosphere. Does this mean that you only need half the area if the array is in space? Is it really worth the extra effort of putting it in space and microwaving the energy down etc?
Japan already has on the drawing board plans to do exactly that. Orbit large PV cell arrays, turn that energy into microwave beams, aim them at the Earth from a geostationary orbit, and have maybe a couple square kilometers of receive antennas that turn that energy back into electricity with high frequency diodes. So they think the idea will work fine. It would for sure be green energy, no CO2, etc.
Originally posted by twhiteheadThe advantage of putting PV cells in space (geostationary orbit 22,400 miles high)(35840 kilometers up) is you almost always have sunlight, the amount of dark time is very short compared to being in sight of the sun.
What are the benefits? You implied earlier that about half the sunlight is lost on entry through the atmosphere. Does this mean that you only need half the area if the array is in space? Is it really worth the extra effort of putting it in space and microwaving the energy down etc?