CEC Performance Model with User entered Specifications error

Hello Forum,

today I've tried adding a PV Modul to SAM. The specifications are from the manufacturer of the module. After entering
the specs I clicked on "calculate" in the "Current-Voltage (I-V) Curve
at STC" and got the error message "could not solve, check inputs".

I checked the specs again but didn't find any deviations from the manufacturers fact sheet.

I tried to run a simulation and got the error message:

"exec fail(pvsamv1): CEC 6 parameter model:  Could not solve for normalized coefficients.  Please check your inputs.
Simulation pvsamv1 failed :exec fail(pvsamv1): CEC 6 parameter model:  Could not
solve for normalized coefficients.  Please check your inputs.
gen not assigned
Simulation grid failed :gen not assigned
SSC requires input 'gen', but was not found in the SAM UI or from previous simulations
Simulation utilityrate5 failed :precheck input: variable 'gen' (System power generated) required but not assigned
SSC requires input 'annual_energy_value', but was not found in the SAM UI or from previous simulations
Simulation cashloan failed :precheck input: variable 'annual_energy_value' (Energy value) required but not assigned"

I 've added a screenshot of the entered specs. Disregard the "Calculated STC Single Diode Model Parameters", as far as I remember, these where added when I clicked the "copy module specs from currently selected CEC database module". Before that, the "Calculated STC Single Diode Model Parameters" window was blank.

When I enter the same PV Module specs in PV*SOL it works and I can run simulations.

I hope somebody can point me in the right direction, because I don't know what to do else.

Thanks in advance.

Hi Torsten,

Please double-check the values and units of the temperature coefficient of Voc and Isc. Be careful that the units selected in SAM match the units on the datasheet.

If all of the data is correct, please try changing the cell type to see if the solver is able to converge using a different cell type.

If you continue to have trouble, please attach a copy of or link to the datasheet of the module you are trying to use.

Best regards,
Paul.

Thank you for the reply.

I have found the problem. First of all, the number of cells was wrong, its 138. But more importantly, I can't use the V_mpp the manufacturer provided, which is 68.1 V, but instead I can use at most 67.96 V. If I use that value it works fine.

Since I mentioned in my first statement: "When I enter the same PV Module specs in PV*SOL it works and I can run simulations.", I think it's only fair to mention now that simulating the electricity generated by the PV system with SAM produces data, that is more consistent than the data produced with PV'SOL (even if I use the exact same PV parameters in PVSOL than I use in SAM (67.96V vs 68.1 V)).

Best regards,
Torsten