Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Solar Cells - Is there anyone here involved in research, production, hobby, etc

  1. Feb 18, 2007 #1
    I have an upcoming paper to write for my solar cells course. The question is something along the lines of, if we have a p-n junction which side should we shine the light on for efficiency? Should it shine on the p side or the n side? Efficiency at this point is defined loosely, and can range from anything to solar efficiency to financial.

    I need a baseline to compare my results. So I need to know what is used in the real world. I'm not asking for a reason why they are used that way. I'll figure this out myself.

    Any help would be great here. Even pointing me in the right direction would be nice. Thanks in advance.
  2. jcsd
  3. Feb 20, 2007 #2
    From a fiscal point of view:running cost, maintenance cost (replacing cells etc..) and initial cost is obviously the optimum values to try and minimize.

    That being said, You will need to investigate the optimum way to set up, run and maintain the solar cells, with a respect to cost. This could be comparisons between installations on a roof/installations on a separate structure or the optimum running voltage/current.

    For solar efficiency, you will simply need to find where the cells would collect the maximum sunlight for the largest period of time possible.

    Those should help you start.
  4. Feb 20, 2007 #3
    Thanks AndreJ for the reply. I will keep that in mind when I talk about the fiscal aspect of operating a solar array.

    The professor finally posted the exact problem statement. Here it is in a nutshell:

    (1) Restrict yourself to a single crystal Si solar cell.

    (2) Which is a more suitable embodiment:
    2.a) p-on-n
    2.b) n-on-p

    define "suitable embodiment" as a factor of:
    a) higher short-circuit current
    b) higher fill factor
    c) other relevant metrics

    (3) Get data for the "suitable embodiment" by solving the diffusion equation with appropriate assumptions. Assumptions such as:
    3.a) monochromatic sun
    3.b) sensible values for: absorption coefficient, lifetimes, mobilities, etc...

    I will narrow my questions down a bit from my previous post:

    1) Is p-on-n or n-on-p used in commercial, or residential solar cells?

    2) How can I find data on the gory details of solar technology actually used?
    (note: I have not actually spent the time to look. I will do this, so if you know off the top of your head, and wouldn't mind responding that would be fantastic.)
  5. Feb 20, 2007 #4
    Most pictures I have seen show the extra electrons flowing in the top layer (so n-on-p). If you think about it, the extra electrons in the n-doped silica are the ones that have to be excited, therefore they should be on top to receive maximal sunlight.
  6. Feb 20, 2007 #5
    Thanks dmoravec. You make a good point.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook