The storage in "PV with storage" is most commonly measured in single digit hours of capacity, and is primarily used in locations where the sun is predictable up during the day and has a predictable discharge/charging cycle of 24 hours. One of the biggest upside is that the economics of it is fairly simplistic with 365 cycles each year that produce predictable revenue.
There is a second form of storage that is also fairly common, which is storage that exist to balance the grid when different units goes up and down. Those generally have even less capacity and are not intended to operate under long periods.
For locations where the first form of PV with storage works, they should really replace everything (with imports handling any exceptional weather events). Storage of this form does however become significant more expensive the further away we get from this optimal weather pattern, and there is a multiple reasons why wind heavy nations can not survive on a few hours of storage. Latitude and seasons can also have a very large impact if a nation where to use this as their only strategy.
There is a second form of storage that is also fairly common, which is storage that exist to balance the grid when different units goes up and down. Those generally have even less capacity and are not intended to operate under long periods.
For locations where the first form of PV with storage works, they should really replace everything (with imports handling any exceptional weather events). Storage of this form does however become significant more expensive the further away we get from this optimal weather pattern, and there is a multiple reasons why wind heavy nations can not survive on a few hours of storage. Latitude and seasons can also have a very large impact if a nation where to use this as their only strategy.