solve block error this variable is undefined

Question

Hi everyone my name is jimmy from Mexico im student researcher my major is electromechanical engineer, i have a project for evaluation of PV modules, and one of my objectives is too use data-sheet information with 4 parameters Voc,Isc,Vmp,Imp from the PV module to extract another parameters (a,Iph,Io,Rs,Rp) that not included in the data-sheet. For that im using a five parameter model to solve that problem, im using the solve block (Given,Find) for a nonlinear systems, the method im using is the conjugate gradient. im attaching my file and you will see all the equations that i use, my problems is that when i put the solve command an error display appear saying that some variable is undefined and i check all the file to see what would be the problem and when i use the track error option put me in the first formula the saying that Iph is undefined. i will really appreciated if you can help me because im new on this software

Best regards to the PTC community.

Werner_E · Accepted Answer

the five equations that i put it is from the model. It supposed works solving with the conjugated gradients method with mathcad solve block (Find,Given).

Nevertheless iot seems that Alan is right and you are missing a fifth equation. Or in other words, there is more you can wish.

Being an underdetermined system would perfectly explain the different results achieved with different methods.

Of course this does not mean that I think that there is mistake in the De Soto model, but maybe it needs some further inverstigation from your side.

Werner_E · Answer

What I spotted on first glance is that1) Rs has no guess value2) Most/All of your five functions don't use all parameters, so these obesolete parameters should be omitted

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