Is there a better method specific for implicit equations? I'm working on extracting lumped parameter equivalent values of a solar cell for single diode model, using experimental JV data. The relevant equation is
J=J0 (exp(q(V-JRs )/(nkB T))-1)+(V-JRs)/Rsh -JL
I measure J,V and using non linear curve fitting methods trying to extract the values for (Jo,Rs,Rsh,n,JL).
Is T (temperature) a constant or a variable in your above model?
I think that the term k[Boltzman]*T needs a specific value for T, if I am right.
Your equation is not an implicit one, it can be solved by using special functions.
It is not elementary, but it can be solved.
@Demetris,
Can you please give me some details on special functions you have indicated? some pointers that would help me track down literature.
Thanks
You have to read about Lambert W function, start from here:
http://en.wikipedia.org/wiki/Lambert_W_function
It has direct application to your model.
Dear Warantaha,
You can use lambertw function to make implicit solar cell equation to explicit one.Then you should apply lsqcurvefit to extract the different parameters from the equation i.e Rs,Rsh,n,Io and Iph. for using lsqcurvefit you need a good initial guess of Rs,Rsh,n,Io and Iph. For your guidance i am attaching the following paper where explicit solar cell I-V equation has been used and parameters are extarcted using lsqcurvefit function.
If you need further help then i am ready to help you. wish you success.
@Demetris & Ashraful,
thank you very much! This is what I have been looking for.
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