One more note on this: For the Inverter Datasheet option, SAM sets the C coefficients of the Sandia inverter model to zero, which effectively removes Vdco from the simulation equations. That is why you don't see a difference in the results over the range of Vdco values you tried.
The C coefficients are small empirical adjustments to the Sandia inverter equations. To learn more about them, see King (2007) listed under "Inverter Models" on the Performance Model documentation page of this website:
sam.nrel.gov/performance
Best regards,
Paul.