The total outlay in that calc is affected by how big of a system you need though.
If you've got no obviously inefficient gear then yes you just put in a system of whatever size is needed.
If you have easy wins on the consumption side then you do that first.
Silly example but say you could eliminate half your consumption with a once off $100 spend then you do that. You don't pay through your nose for an system twice the size just because of ""free"" power later.
Where that cutoff point lies will require calculation, but chances are old enterprise racks are on the wrong side of it.
It's really unlikely that most people will gain a lot of money from these kinds of installations nowadays (an EV probably tips that somewhat).
The big benefit is the resilience. Since you are using them every day, they will be far more likely to work in the event of an outage than a gasoline generator that you test once a year.
