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PV cell spectral sensitivity?

Discussion in 'Photovoltaics' started by Mark Fergerson, Oct 19, 2004.

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  1. I was sent here from sci.electronics design, so if I'm
    asking a question that's in a FAQ someplace, please point me
    there.

    I've been trying to find out what part of the spectrum
    your common silicon cells scavenged from calculators best
    convert to current, but the best I've been able to find
    after Googling myself silly is the fact that the bandgap for
    silicon puts their sensitivity peak in the near-infrared.

    Some claim that such cells are antireflection-coated
    which would explain the different colors they come in, but
    others claim that's just a moisture barrier and the most
    efficient ones are dark blue, which makes sense if they like
    NIR best.

    Why do I care? I want to hide some cells behind fake
    gemstones for a project. If the cells do prefer NIR, it's
    going to make it interesting to find fake stones that will
    pass enough NIR to be worthwhile. Not impossible, it just
    means I get to do a lot of testing.

    Is there anyone/a site that can set me straight, or am I
    doomed to the tedium of finding out for myself?

    TIA

    Mark L. Fergerson
     
  2. George  Ghio

    George Ghio Guest

    Would you like a chart (graph) of this? PDF.

    George
     
  3.  
  4. asking a question that's in a FAQ someplace, please point me
    there.your common silicon cells scavenged from calculators best
    convert to current, but the best I've been able to find
    after Googling myself silly is the fact that the bandgap for
    silicon puts their sensitivity peak in the near-infrared.
    crystalline silicon).

    That's the reverse of my original impression. However,
    upon close inspection they don't have the same obvious
    crystalline appearance as do old-fashioned large-grain
    polycrystalline cells I have on hand. I was unsure whether
    modern cells might be single crystals that wouldn't show the
    obvious grain structure the old ones do.
    which would explain the different colors they come in, but
    others claim that's just a moisture barrier and the most
    efficient ones are dark blue, which makes sense if they like
    NIR best.
    Black, nearly violet, dark blue, leaf green, a strange
    greenish-brown, and the rust/dark red you say is CdTe.

    Oh, dear. This is getting more and more complicated.
    googling.

    Yes, the few numbers I could find were for crystalline
    Si. Can you point me to a comprehensive data source on the web?
    That's a relief. I'm getting similar voltage/current
    numbers from "unhidden" cells of various colors, so I'll
    stop worrying about their chemical composition.
    gemstones for a project. If the cells do prefer NIR, it's
    going to make it interesting to find fake stones that will
    pass enough NIR to be worthwhile. Not impossible, it just
    means I get to do a lot of testing.
    Right; I'm aware that the sensitivity of the cells are
    curves as opposed to narrow peaks. I'd about settled on
    amethyst because I have plenty and it's relatively easy to
    work, but it does absorb green strongly (I'm interested in
    running some low-power circuits from sunlight and
    incandescent room lighting) and there'll be a lot of light
    going to waste if I do that.

    The idea is to hide the fact that the cells are there
    while allowing them to do their job. I may just go with
    straight quartz and rough it up a bit on the backside into a
    diffuser.
    I expected to do quite a bit of testing, but I wanted to
    have a starting point to avoid time wasted slabbing the
    wrong materials.

    Thanks for your help.

    Mark L. Fergerson
     
  5. George  Ghio

    George Ghio Guest

    Hi Mark

    Sorry for the break but the server has been down.

    If you would like a graph of spectral sensitivity Where would you like
    it sent.

    George
     
  6. Stuff happens.
    mfergerson(one)(at)cox.net

    Decode as appropriate. Spambot harvesters are getting
    smarter. :>(

    Thanks again

    Mark L. Fergerson
     
  7. If possible, could you also send a copy to wookie(at)wookie.demon.co.uk
    please ?


    Thanks, J/.
     
  8. George  Ghio

    George Ghio Guest

    Not a problem

    George
     
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