If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #223
Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125
One thing that I noticed about solar cells is that they need to be really large to generate any decent amount of electricity. However I came up with a rather crazy idea. Why not use a lens to focus more light energy onto a smaller cell. Obviously you would need to solder them to a copper block to keep them from getting too hot but It sounds feasible. This method would have it's limits but I’m wondering if it would be worth it. Just as an experiment I have a good sized copper block that would fit two radio shack cells nicely. These cells only put out 0.5v at 0.5V usually. Using one of those page magnifiers (a fernells[sp?] lens) I should be able to at least double the output current. The main problem I would think is keeping them cool. I mean it would have to be passively cooled in order to save any increases made. Maybe I can cheat and use running water from a small stream to cool them off.
Registered Member #53
Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638
The only issue I can think of would be if the cells use a wavelenght of light that the magnifer would block (glass blocks some uv if i remember correctly). I thought of this because I noticed that those radio shack cells don't generate alot of anything when under artificial light (even when close to the source). Just a thought.
Registered Member #71
Joined: Thu Feb 09 2006, 08:23AM
Location:
Posts: 63
This method of 'boosting' the output of solar cells is already being used. There are special reflective parabolic dishes that are designed to concentrate sunlight onto a relatively small solar panel. This is cooled with oil pumped around it.
There are a few on experimental runs here in Australia, although I can't remember where.
Registered Member #223
Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125
Well those page magnifiers are made of some sort of plastic so I don't know if it would block a specific wavelength that the solar cell uses. But if that fails I could use mirrors. I never heard about this before it's just a random thought I had. It's a rather simple concept though. I know there would probably be a point of diminishing returns. One thing I'm not sure about is if it possible to saturate a solar cell or will it just generate more and more power the more light you focus on it until it gets too hot. but I guess I'll find out in my little experiment.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
Fresnel lenses are fine, I have used one on a solar panel from a garden light and got eight times the normal output. I cooled the panel with water. Solar cells does not generate much energy in fluorecent light. That is why fluorecent lights are effective, they mostly contain energy in the frequencies in the visible band. If you use a normal light bulb a solar panel is probably more efficient than in sunlight because it contains more IR.
One of the problems is the internal resistance of the solar cells, so overdriving them causes a large of loss. There are special cells that are made to be overdriven by 300-1000x, they are probably very expensive.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
When we get around to using solar cells to generate energy (hopefully soon, the company I work for has a $60mil contract for terrestrial solar cells) we will be using your method.
However, it will be a much larger magnification factor... I believe they are planning to use a 10' diameter disk focused on to a 4" square of cells (100x) which should give about .5-1kw a peice. To deal with cooling they will plan to use liquid sodium.
I have a few (20ish) old concentrator cells (from when my dad was working at texstar) that are about a 1" square, with about a .8" in diameter active region. I don't have big lenses to try it out, but with water cooling (1'^2 of sun is about 100w) you should be able to get at least 10w of power from 12" fresnel lens.
I wouldn't really worry about blocking out the uv, as a uv photon gives the same amount of energy as a far ir photon, so you aren't really blocking too much out.
Registered Member #223
Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125
Well those page magnifiers are about the size of a letter sized piece of paper. But I had seen some reflective film stuff at a hobby supply store. it was about 2ft wide and was on a roll of 10ft or so. I could build a support frame for it a make it into parabola. Sort of like this. But I’ll try the magnifier first. These solar cells are about 2cm x 4cm and only put out 0.25W in full sunlight normally! If I could get even 5W with a page magnifier and two small solar cells that would be a huge improvement! One thing i'm conserend about is soldering them to the copper block. First will they be able to survive the tempratures needed to solder them (~200C). Secondly their backs are soldered to a copper bar only so only a parallel configuration is possible limiting the output voltage. They only put out out 0.5V under normal sunlight so I'm hoping under the lens it will boost it to at least 1.5V. This would at least be a usable voltage. Current shouldn't be much of a problem and would probably be able to supply a few amps.
Registered Member #223
Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125
Rats.. With only 0.5V the max current (and power) I can get from it will severely be limited. Plus getting a DC-DC converter to run off of 0.5v would be a very challenging feat if not impossible. So it seems like I can't just solder them to a copper block after all. I would need some sort of insulation between the cell and the heat sink in order to wire them in series. Although finding something that is non-electrically conductive and still has good thermal conductivity will be rather difficult. Hmm seems like a fruitless effort then.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
That is the problem with heat sinking solar cells, they need to be electrically isolated I wonder what it would cost to get a big sheet of a high conductivity ceramic that is tinned on both sides so you could etch it into some seperate pieces, solder it to the heatsink/waterblock, and solder the cells...
Yo could always use seperate heat sinks for each cell...
On that note the cells should take the heat fine, but it is probably best to minimise the time they are at temp. The real concentrator cells had the contacts welded becuase they ran too hot for solder
Or you could use some triple junction cells which would give a little over 3v... I know I have a few arround here somewhere, but considering that they were sold for thousands of dollers a cell...
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.