There may be possibility that in older version "Lower temperature for Absolute Voltage Limit" set @ 0°C however as per attachment "PV Syst" Set temp. is -10°C resulting 1020V which is exceeding inverter maximum input voltage and not allow to take 20modules in series due to same.
Hence go to Project → Project Setting → Design Conditions and set the "Lower temperature for Absolute Voltage Limit" value as weather file.
Also find below details.
PV Syst Design Temperature.jpg [ 88.04 KiB | Viewed 2246 times ]