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Discussion in 'General Electronics Discussion' started by cspannos, Jul 24, 2010.

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  1. cspannos

    cspannos

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    Jul 24, 2010
    Hello,

    I am looking to power some solar panels artificially for testing purposes in a project I am working on. My question, is there any type of light bulb that would work best for this?

    I am trying to make a 12" x 12" light panel using CFLs to keep the heat down to a minimum, but still try to get the highest lumen output I can find. I came across this setup which is meant for hydroponics:

    http://www.stealthhydroponics.com/product.php?xProd=120&xSec=3

    It looks small enough, but I wasn't sure if I have to worry about the specific light spectrum this thing outputs or just worry about the total lumen output.

    I read this about solar panels and light spectrum requirements, but really still need some guidance I think. I will be using solar panels like these:

    http://www.siliconsolar.com/flexible-solar-panels-3v-051287-p-500996.html
    http://store.sundancesolar.com/susoce0500ma.html
    http://store.sundancesolar.com/supsolcel5v1.html

    Would I get the most power out of a Blue, vegetative spectrum or a Red, Flowering spectrum when it comes to these CFL's?

    Thanks,
    Kosta
     
  2. trobbins

    trobbins

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    Jun 15, 2010
    My gut feeling is to check the typical single crystal spectrum response (if you end up using single crystal) and determine the peak frequency response range where power output is greatest. Then you need to work out what the cfl spectrum power distribution is - I think it will be focussed into peaks close to the blue region where 50k temp aligns. If you find good references for either of those areas then good to post back. I have seen the single crystal spectrum years ago but can't find a link.

    Ciao, Tim
     
  3. cspannos

    cspannos

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    Jul 24, 2010
    Thanks for the response trobbins. The only thing is that these CFLs that have such a high lumen output are quite expensive. I really don't have any to test with yet. I want to be able to purchase the right one. I was hoping someone would just... well, "know the answer" I guess, lol.
     
  4. trobbins

    trobbins

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    Jun 15, 2010
    You do have to worry about the frequencies the cfl outputs at, because if they don't align with the cells peak response then compared to other light sources you may be paying for wasted lumens, and it may be better to go to other light sources that are less lumens.
     
  5. cspannos

    cspannos

    14
    0
    Jul 24, 2010
    Hi trobbins,

    I really do agree with you. I think I am going to try to find some lower wattage, cheaper CFL bulbs at the hardware store that have similar lumen output, but at different color temperatures.

    23 Watt (100W) Soft White, 27K
    http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

    23 Watt (100W) Bright White, 35K
    http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

    23 Watt (100W) Daylight, 65K
    http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

    Then I will just hook up a multimeter to a small solar panel and see which CFL I get the most output from. I'll have a bunch of extra bulbs, but I'm sure I can make use of them around the house I guess. I will post the results soon....
     
  6. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    I don't know how photovoltaic cells work exactly, but if radiant power is a factor then you would be better to look toward HID lights. Even then I think a 250 watt HID will provide as much lumen's as those particularly expensive CFL's. You don't need those expensive ballast they use in hydroponic setups.

    http://www.1000bulbs.com/product/5020/MH-025001P.html
     
    Last edited: Jul 27, 2010
  7. cspannos

    cspannos

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    Jul 24, 2010
    Wow, you are definitely right about the price difference for the bulb itself. I knew about HIDs but stayed away from them because they get burning hot like halogens. They operate under high pressure and temperature, and need special fixtures which are just as expensive: http://www.1000bulbs.com/product/755/HLF-400NFB250MH.html
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
    2,820
    Jan 21, 2010
    I'm a little curious as to what you're doing this for. I presume it's a demonstration of something.

    I also presume you're not trying to use the power generated to light the bulb(s) :p :)
     
  9. trobbins

    trobbins

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    Jun 15, 2010
    The linked paper has a graph that indicates you are best served by using a CFL light source with the dominant spectral peak(s) more into the red end than the blue end (eg 900nm peak for monocrystalline cells).

    http://www.pvmeas.com/solarcellspectralresponse.pdf
    http://www.pveducation.org/pvcdrom/solar-cell-operation/spectral-response

    And a summary of the spectral response of some common light sources is:
    http://intiridesigns.com/articles/color.php

    So you will be like a moth attracted to the 'bright' light if you go for your high lumen blue end cfls - rather than the safety (and much higher efficacy) of say a tungstan halogen bulb.
    http://www.oceanoptics.com/products/ls1.asp
    http://zeiss-campus.magnet.fsu.edu/articles/lightsources/tungstenhalogen.html

    Ciao, Tim
     
  10. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    There again, you do not need to buy that fixture for a HID to work. I bought my HPS ballast used $150 (400 watt) and bought $20 bulbs for it at home depot. Look around online. The only part of a HID that you need new is the bulb so you receive the max lumen's possible. Any bulb even a CFL will have losses overtime. Besides you will have a great outdoor night light when your solar panel project is over with.

    Do you plan on using this whole thing inside on a permanent basis? A halogen bulb will get a lot hotter then a HPS, MH or even mercury vapor.
     
    Last edited: Jul 28, 2010
  11. trobbins

    trobbins

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    Jun 15, 2010
    The spectrum assessment indicates that a HID or CFL will be much less effective light sources than the tungstan halogen bulb in transfering Watts of energy to a monocrystalline pv panel.
     
  12. cspannos

    cspannos

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    Jul 24, 2010

    Haha, no... not trying to power any light bulbs here. I'm building a lot of little BEAM robots that are powered by small solar panels. I'm setting up a kind of terrarium to bring them all to life in one shot with the flip of a switch. Some walk around, some flap their thin solar panel wings, some make noises, etc....

    Yes, I'm a wierdo I know :) Just figured I'd beat you guys to it.
     
  13. cspannos

    cspannos

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    Jul 24, 2010
    This explains alot! Thanks so much!! But this still means I can go for a 5500K or 2700K CFL, no? The heat issue is still there with a halogen.
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
    2,820
    Jan 21, 2010
    Nah, BEAM robots are really amazing in their own way.

    The advantage is that many will operate from comparatively low light levels, so the level of illumination may not be terribly critical.

    If you can take a video if them when you're finished and post us a link, I'd certainly like to see it.

    As for what light to use. It seems that you could do a simple test by buying one of each globe and placing them a set distance from one of your BEAM robots. See which one works best.
     
  15. cspannos

    cspannos

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    Jul 24, 2010
    It'll prob be a while, but I'll definitely post a link to a video!
     
  16. trobbins

    trobbins

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    Jun 15, 2010
    The heat content of the light source can be filtered out to a considerable degree by a suitable front glass. You may be able to find 12V 'downlight' reflector modules with a suitable filtered output - and these would be substantially cheaper than any other form of intence light source. And of couse you need to cool the lamp bulb itself without that heat getting to your terrarium.

    I still suggest that the qu-hal bulb will provide much more power output from the mono-Si cell(s) you have - compared to any other bulb (W for W).

    The other path to take is to change your choice of PV cell - however I think any option will most likely be inherently less efficient and of no nett benefit.

    Tim
     
  17. bensonbarton

    bensonbarton

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    Jul 29, 2010
    thanks a lot for ur useful information
     
  18. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    I happen to be watching tv the other day and on the science channel "How is it made" they had solar panels. To quality control the process of the solar panels they would measure the power produced from the panel when it was tested using a HID light. They did not say what light they where using, but it looked like either a mercury vapor or metal halide. It's hard to say what their purpose was for using a HID light, but I think it certainly validates there usage with solar panels inside as a test bed.
     
    Last edited: Aug 6, 2010
  19. trobbins

    trobbins

    83
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    Jun 15, 2010
    jacko,

    The principal characteristic of a solar simulator for testing PV panels is stability of light output over time (measurement time, and drift). The spectral response differences are accounted for by a calibration constant using reference cells. A simulator can have very poor power transfer performance - as that is of no consequence to its application.

    Ciao, Tim
     
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