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Solving Diode Equation for Current?

  1. Oct 5, 2014 #1
    1. The problem statement, all variables and given/known data

    I need to find the current, but not sure how to rearrange the equation because of the I in the exp.

    2. Relevant equations


    3. The attempt at a solution

    Thanks, just need to be pointed in the right direction. Seems like I will either be in ln or exp.
  2. jcsd
  3. Oct 5, 2014 #2
    Also, just a follow up question, the diode ideality constant... Is there a way to solve for it? My notes just say its between 1 - 1.5, Should I just assume its 1? The manufacturers data sheet does not mention a value for this.
  4. Oct 5, 2014 #3


    Staff: Mentor

    Because I appears on its own and as the argment of the exponential, you can't solve for it using elementary operations.
  5. Oct 5, 2014 #4


    Staff: Mentor

    Are you talking about I0? That one you can solve for.
  6. Oct 5, 2014 #5
    No, I'm talking about just I. So how would I go about finding it?
  7. Oct 5, 2014 #6
    Using numerical methods
  8. Oct 5, 2014 #7
    Thank you, I used newtons method on matlab, I think it should be correct :)

    Also, do any of you have an idea about the diode ideality factor? Im trying to model a PV module in Matlab and the data sheet does not mention this. I read online that people tend to assume its just 1... Any ideas?
  9. Oct 5, 2014 #8
    Nevermind!! After running through the code using different values (between 1 and 2), There is no difference in terms of the current... well either, it can be neglected or my code is wrong (I tried entering a large number, that affected the current)
  10. Oct 6, 2014 #9


    Staff: Mentor

    Which variable is the diode ideality factor? That's what I was asking about in post #4.
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