How To choose different Inverters for different Sub arrays

Hi, I am new to SAM, and apologies if my questions are of very Basic Level . But I searched a lot and couldn't found any satisfactory answers. I have problem with two things ,

1. How to choose different Inverters for Different Subarrays of my choice.
2. Why fixed monthly Cost in Electricity Cost Section have no effect on NPV or Payback when doing Parametric Analysis.

I will really appreciate your help.
Thanks
Regards Muhammad Haroon

Hi Muhammad Haroon,

SAM can only model photovoltaic systems with a single type of inverter. It is not possible to assign different inverters to different subarrays.

The fixed monthly charge on the Electricity Rates page may not have a significant effect on the NPV or payback period if it is small compared to the total energy and demand charges in the electricity bill, or if the electricity bill savings are small compared to the cost of operating the system. You can see those values on the Data Tables tab of Results page under "Monthly Data." For example, you can compare the "Fixed monthly charge with system" and "Energy charge with system" values.

Best regards,
Paul.