Its advantage is continuity of supply - ground based PV in a single location is only available for about a third of a day.
Building transcontinental and transoceanic UHV power transmission lines circling the northern hemisphere, providing the same function is probably cheaper, but may be more politically difficult.
But that's moot. We have a cornucopia of viable storage methods in active development--viable meaning capable of being scaled up to global scale in 20 years or so.
Form Energy's iron-air battery, for instance - good at the two days to two weeks duration, needed as backup for wind during prolonged calms. We already mine a great deal of iron; the extra needed globally wouldn't really be noticed. Others are working on iron-air also.
At least a couple of teams are quite far along with hot rock energy storage. Good for the one week to one month timescale.
Various other battery technologies for sub-day timescales - lithium for grid frequency stabilisation, flow batteries.
I don't know of any active trials of ammonia energy storage, one of the most scalable candidates for seasonal storage, but ammonia engineering is very old and very widespread, so there don't appear to be roadblocks to scaling up rapidly once required.
The YouTube channels "Just Have a Think"[1] and "Undecided with Matt Ferrell"[2] focus on this stuff, and do some research.
Edit: you should be sceptical; well done! Scaling really does take forever. That's why the only viable technologies are those already lying around all over the place, being used for other things.
Building transcontinental and transoceanic UHV power transmission lines circling the northern hemisphere, providing the same function is probably cheaper, but may be more politically difficult.
But that's moot. We have a cornucopia of viable storage methods in active development--viable meaning capable of being scaled up to global scale in 20 years or so.