There is already interconnects between South Australia and Victoria as part of the NEM [1] that covers the grid along the south and east coasts, along with Bass

There is already interconnects between South Australia and Victoria as part of the NEM [1] that covers the grid along the south and east coasts, along with BassLink to/from Tasmania. So an overland or sea route from Perth to Adelaide, potentially following the existing rail lines would get you the advantages of the time zone differences as well as integrating Perth into the NEM.