# Solar panel model (2 R, a current source and a diode) question

#### hrstar24

Joined Apr 7, 2009
32
I need to figure out the general parameters for a solar panel. Here is the model that I need to use. I already have this equation, which I believe is correct in order to solve for Icell: Now, I need to solve for the following parameters: Io, Ido, Rp, and Rs. Ido is the coefficient in the diode equation for Id. I have taken a bunch of points for Vcell and Icell, enough to generate an iv curve. Otherwise, I have no other information given.

My first line of thought was to figure out Io, by shorting Vcell, so then Icell = Io. After this, I got stuck. Since I only have 3 unknowns left, I was thinking of maybe plugging in 3 different Vcell/Icell pairs into the equation given, and then using a program like MATLAB to churn out the 3 missing variables, but I don't know if this would work.

Another idea I had was that in my Icell/Vcell curve, the initial nearly flat slope of the plot is equal to 1/Rp, and then the steep slope at the end of the plot is equal to 1/Rs, like shown below: Will this work?

Anyone know if there is an easier way to do this without matlab? How do I go about figuring out Ido, Rp, and Rs?

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