Dear Mike,
First of all, for a description of PVWatts V5 and the differences between V1 and V5, please see Dobos (2014) listed under PVWatts on the SAM
Performance Model Documentation page
of this website. Differences between the two models are highlighted in boxes throughout the document.
In your inputs to the pvwattsv5 module, the losses input should be 14, not 0.14.
Also, to be more consistent with pvwattsv1, set module_type = 0 (standard) and array_type = 0 (fixed open rack).
Please see Section 11 of the PVWatts V5 reference manual for a description of how to convert between a V1 derate factor and V5 loss value.
Because of the differences between the V5 and V1 models, you should see some difference in the results, even after you calibrate the inputs to be as similar as possible. But, the differences should be relatively small. V5 is the current version available on the PVWatts website and that SAM uses, so you should consider that to be the more accurate model.
Best regards,
Paul.