Dear Bill,
Thank you for the clear statement of your question, and for providing supporting documents.
For some types of modules, the algorithm SAM uses to calculate the six parameters of the CEC module model fails to find a solution. This is particularly true for thin film modules because of the
a parameter, or "modified nonideality factor", as described in Dobos 2012 (see the Detailed Photovoltaic Model references at
sam.nrel.gov/performance).
We'll look into this further and I will follow up when we learn more.
Best regards,
Paul.