Lots of data centers are, and will remain, off grid. Redundant power supplies, nat gas generators, and diesel back-up are the more common arrangements due to the uptime requirements.
Discussion
No way you’re off grid with renewables only. That’s not reliable enough for a top tier DC
Best off grid is you overbuild solar, add some batteries and a liquid propane generator. Can’t do with solar alone but if sized right you are only running your generator a handful of times a year. Maine did this with some remote cell tower locations several years ago.