From the previous open Nem link this is SA for the last week
This is the reported curtailment for the same week from nemlog: nemlog curtailment
In my opinion additional solar will not help in the night when gas and imports were used. Additional wind would help a little but because there were lower wind conditions due to High Pressure systems the capacity factor was low which means the existing wind farms were not performing at levels used in the modelling or LCOE justifications. A lower capacity factor increases the cost per MWh
If the transmission line's capacity is 800-900MW then it would allow the existing curtailment to be exported however it's main purpose is give SA access to supply from NSW if the gas is to be reduced as demonstrated in the top chart.
The curtailment quantity above helps quantify the amount of storage required to make this work. For context the big battery is 129MWhs and the new upgrade takes it to 196MWh's
