Error when trying to input user specified values for CdTe module CEC model

  • Koami Soulemane Hayibo
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18 May 2024 16:06 #13174 by Koami Soulemane Hayibo
Hello,

I am simulating a system with a CdTe module not in the CEC database. I have input all the values according to the manufacturer's specifications sheet but when I tried to plot the IV-curve, I got the following error: Could not solve, sanity check failed (-2): Il < 0.5 || Il > 20.0

My hunch is that SAM does not accept PV modules with short-circuit current values of less than 0.5A and more than 20A. Is my hunch correct? If not, could someone please let me know what that error might be and how to fix it?

The details of the PV modules I have are as follows:
  • Module Power: 24 W
  • Cell Type: CdTe
  • Vmp: 88.4 V
  • Imp: 0.27 A
  • Voc: 118.7 V
  • Isc: 0.32 A
  • Temperature coefficient of Voc: -0.321 %/°C
  • Temperature coefficient of Isc: 0.06 %/°C
  • Temperature coefficient of power: -0.214 %/°C
  • Number of cells in series: 140
  • Nominal operating temperature 47.3 °C
  • Module area: 0.72 m²
  • Module aspect ratio: 2

Regards.

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  • Paul Gilman
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20 May 2024 15:09 #13178 by Paul Gilman
Hi Koami,

Make sure you change the units for the temperature coefficients of Voc and Isc if you enter them in %/°C:

 

If you are using the correct units and continue to have trouble, please attach a .sam file with the data you entered so I can help troubleshoot.

Best regards,
Paul.

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  • Silvia Ma Lu
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26 Jul 2025 03:10 #14181 by Silvia Ma Lu
Hi Paul,

Not sure if this has been solved or if anyone found a solution. I got the same problem as Koami describes and the error still appears when the temperature coefficients of Voc and Isc are in their correct units %/°C. 
It seems that SAM does not allow for modules with short-circuit currents (or maximum power current) below 0.5 A. Since the error is Could not solve, sanity check failed (-2): Il < 0.5 || Il > 20.0

However, many semi-transparent CdTe modules in the market have currently these currents below 0.5 A. Is it possible to override that sanity check, or lower the lower limit in SAM? 

Thanks,
 

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  • Paul Gilman
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28 Jul 2025 09:44 #14186 by Paul Gilman
Hi Siliva,

Can you share a manufacturer datasheet for the semi-transparent CdTe module you want to model in SAM?

We are working on a new mathematical solver implemented in Python that calculates coefficients for SAM's modified single-diode model: github.com/NREL/pysam/pull/195 .

Best regards,
Paul.

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  • Silvia Ma Lu
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28 Jul 2025 10:03 #14188 by Silvia Ma Lu
Hi Paul,
Thanks for the quick reply and updates. Looking forward to the new implementation. Yes, find attached the datasheet from the manufacturer. Particularly for the most-transparent, lowest short-circuit current module, is where I got problems with SAM. 

Thanks for the help!
Best,
Silvia

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