Hi Nathan,
Not all input variables are available as inputs for parametric and stochastic simulations. For a PV array consisting of more than one subarray, the number of strings allocated to each subarray must equal the total number of strings in the array as defined by the "strings in parallel" input. The System Design user interface page checks that to prevent you from designing a system with inconsistent subarrays. There is not a way to control that for parametric and stochastic simulations, so we decided not to allow the variables to be inputs for those simulations. When you run a parametric or stochastic simulation, SAM sets the number of strings in each subarray to the values shown on the System Design page.
You can access those variables in LK script (subarray1_nstrings, subarray2_nstrings, subarray3_nstrings, subarray4_nstrings). Obviously, you have to be careful in your script to assign values such that the total number of strings is equal to strings_in_parallel.
Best regards,
Paul.