LabVIEW
One-diode model fitting using nonlinear curve fit
I am trying to fit the I-V curve of a solar cell using the one-diode model. The equation of this model is
The goal is to extract I_0, Rs, Rsh and n. I and V are the variables, the rest are constants.
I_ph can be removed, since it's just an offset that is easily found from the data.
Following the suggestions in these topics: Fitting Non-ideal Diode equation, non linear fit for diode equations and
, I is moved to the right to format the data for the Non-Linear Curve Fit VI:
For the fitting model, I have this:
Here is an example curve
The issue I'm having is that, although the fitting doesn't give an error, some parameters aren't reasonable:
The data is very typical of a silicon solar cell, as are the guess parameters. (Rs and Rsh guesses are extracted using the slope of the curve at V=0 and I=0, respectively). I've followed the suggestions of the abovementioned topics, which were said to have worked. Did I do something really wrong?
I have attached the VIs with example data.
