Hi Alejandra,
SAM's automatic sizing algorithm is described in the Help topic for the System Design page, under "Estimate Subarray 1 Configuration":
samrepo.nrelcloud.org/help/pv_system_design.html
For some of the desired sized in the parametrics table, the sizing algorithm fails. For example, Run 31 fails:
You can see what the inputs are for Run 31 in the Parametrics table:
You can test that desired array size on the System Design page:
A better approach might be to disable the Estimate Subarray 1 configuration option, and instead change the number of strings in parallel to change the system size. You'll also have to change the inverter size. Or you could try using a small module (maybe around 120 Wdc) and small inverter (around 100 Wac to work with the 1.2 DC/AC ratio).
Best regards,
Paul.