Fwd: New solar cells could even work at night!
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James DeMuth
Dec 21, 2010, 1:32:33 PM12/21/10
to RCLReid, Leah Reid, JSIP, Jodie DeMuth, Rick DeMuth, Dennis DeMuth
Very Interesting!
-James
New solar cells could even work at night
by Staff Writers
Idaho Falls, Idaho (UPI) Dec 20, 2010
U.S. researchers say they've developed a new kind of solar cell that can generate energy even at night, promising a new form of renewable energy.
The key is their ability to harvest infrared radiation as well as visible light, Steven Novack at the U.S. Department of Energy's Idaho National Laboratory in Idaho Falls says.
Almost half of the available energy in the spectrum of solar radiation resides in the infrared band, and infrared is re-emitted as heat by the Earth's surface after the sun has gone down, meaning the cells can even capture some energy during the night, he says.
Novack estimates a complete system using the new cells would have an overall efficiency of 46 percent, whereas the most efficient current silicon solar cells top out at about 25 percent.
Also, currently solar cells can only produce their top output in a narrow range of conditions. For example, if the sun is in the wrong position, sunlight is reflected off a silicone solar cell instead of being absorbed to create energy.
The new cells can absorb radiation at a variety of angles, the researchers say.
by Staff Writers
Idaho Falls, Idaho (UPI) Dec 20, 2010
U.S. researchers say they've developed a new kind of solar cell that can generate energy even at night, promising a new form of renewable energy.
The key is their ability to harvest infrared radiation as well as visible light, Steven Novack at the U.S. Department of Energy's Idaho National Laboratory in Idaho Falls says.
Almost half of the available energy in the spectrum of solar radiation resides in the infrared band, and infrared is re-emitted as heat by the Earth's surface after the sun has gone down, meaning the cells can even capture some energy during the night, he says.
Novack estimates a complete system using the new cells would have an overall efficiency of 46 percent, whereas the most efficient current silicon solar cells top out at about 25 percent.
Also, currently solar cells can only produce their top output in a narrow range of conditions. For example, if the sun is in the wrong position, sunlight is reflected off a silicone solar cell instead of being absorbed to create energy.
The new cells can absorb radiation at a variety of angles, the researchers say.
marc fawzi
Dec 22, 2010, 1:30:10 PM12/22/10
to js...@googlegroups.com
"
(see: http://www.physike.com/oldweb/%E8%B5%84%E6%96%99%E4%B8%8B%E8%BD%BD/%E5%A4%AA%E9%98%B3%E8%83%BD%E7%94%B5%E6%B1%A0/High-efficiency%20solar%20cells%20from%20III-V%20compoundfulltext.pdf)
For infrared, they may be using something other than silicon, e.g. GaAs, that has the right band gap(s) for infrared, but I'm accessing ancient memory here.
5% is a great leap in any case -- I think the first solar cell only had 10-18% efficiency.
--
Marc
"We assume that space-time at the Planck scale is discrete, quantised in Planck units and "qubitsed" (each pixel of Planck area encodes one qubit), that is, quantum space-time can be viewed as a quantum computer. Within this model, one finds that quantum space-time itself is entangled, and can quantum-evaluate Boolean functions which are the laws of Physics in their discrete and fundamental form." --Paola Zizzi
whereas the most efficient current silicon solar cells top out at about 25 percent."
I believe the efficiency (conversion ratio) of *traditional* cells is up to 39% these days(see: http://www.physike.com/oldweb/%E8%B5%84%E6%96%99%E4%B8%8B%E8%BD%BD/%E5%A4%AA%E9%98%B3%E8%83%BD%E7%94%B5%E6%B1%A0/High-efficiency%20solar%20cells%20from%20III-V%20compoundfulltext.pdf)
For infrared, they may be using something other than silicon, e.g. GaAs, that has the right band gap(s) for infrared, but I'm accessing ancient memory here.
5% is a great leap in any case -- I think the first solar cell only had 10-18% efficiency.
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Marc
"We assume that space-time at the Planck scale is discrete, quantised in Planck units and "qubitsed" (each pixel of Planck area encodes one qubit), that is, quantum space-time can be viewed as a quantum computer. Within this model, one finds that quantum space-time itself is entangled, and can quantum-evaluate Boolean functions which are the laws of Physics in their discrete and fundamental form." --Paola Zizzi
Tim Sennott
Dec 26, 2010, 9:33:56 AM12/26/10
to js...@googlegroups.com
39% is at concentration and with specialized multi-junction (non-silicon) cells (read very expensive). 25% is peak for Si cells, best commercially are sunpower (presently 19.5ish). Other non Si techs like CIGS are coming along but at ~11% commercially. These are to the best of my knowledge.
Very curious about this tech, anyone find real papers? I'm computerless for holiday. Garrett I'm lookin at you.
Seems like antennae would have to exploit craZy resonance/coupling to capture as broad a band as the solar spectrum. Guess I could see that though. Harvesting the Infrared down to 300K seems stupid though, so little energy there...relying on sky cooling to drop cell temp below ground temp and harvest that delta? Ya, sure.
People with computers send more stuff!
Marc Fawzi
Dec 26, 2010, 1:03:36 PM12/26/10
to js...@googlegroups.com, js...@googlegroups.com
I thought concentration is achieved via optical means (a lens over each cell?) and it's practical enough to do with a plastic lens array/sheet?
there is a type of acrylic lens called a 'cone lens' that is basically a tapered waveguide with a concentrating lens on the wide end (base of the cone) and I can see such cone lenses being big enough to act as cheap/practical single cell concentrators where the tapered end simply buts against the cell
Merry Xmas/Happy Holidays
Envoyé de mon iFoam
Envoyé de mon iFoam
Tim Sennott
Dec 26, 2010, 1:39:28 PM12/26/10
to js...@googlegroups.com
Yep, concentration is optical and theoretically cheaper/more efficient, but cells designed take advantage of it are more expensive. Regular cella can see low concentrations but little performance boost.
Hardest thing about concentrating is tracking. Most optics require pointing a the sun, which makes things complex. Some optics (CPC, for example) are non-tracking, but uniform flux distribution on cell then becomes a challenge.
Plus concentrators require direct sunlight, not as plentiful as "global" (5-10% loss on sunny days, 100% loss of overcast ones)
I think the future of solar will be cheap, non-concentrating cells. Efficiency is really less of an issue than cost. And the Chinese are winning that.
T
Caitlin O'Brien
Dec 26, 2010, 5:35:58 PM12/26/10
to js...@googlegroups.com
I'm no engineer, but I do know carbon nanotubes can collect IR and concentrate energy. I came across this a few months back and sent it to Tim:
I'm stuck at the airport and can't get ahold of the original papers, but you can check 'em out for yourself.
Caitlin
gcfitz...@gmail.com
Dec 26, 2010, 5:37:24 PM12/26/10
to js...@googlegroups.com
Ill find some journals on them when I get a chance, I'm in the mts for a few days.
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Subject: Re: [JSIP]: Fwd: New solar cells could even work at night!
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