See, you don't really get the scale. It's not practical, the land size where it needs to be would be immense, and all the numbers below get worse as you go north. This would be around Texas.
These things would need to run in the winter when the output is worst. You would need approximately 7GW of solar to power a 1GW datacenter and charge the batteries to run on off sun hours. That battery would need to be 16 GWh.
Except, that's perfect winter weather. It's not always perfect winter weather, it needs a buffer, likely at least 1+ day of buffer for when there is no sun, so thats another 24GWh of battery, and that 24GWh of battery needs another 7-10GW of solar to keep it topped up appropriately.
So 23-26 14-17 GW of solar and 40GWh of battery and you can have some bad solar days with a complete 1 day backup if everything is taken offline, but you really think they would build something like this completely off grid that only has 1 day of backup?
That's 14-17 times the largest solar field active in the USA today, and 13 times the largest battery.
Getting all that space, permitting it all etc would take years on it's own.
Thats why they're all doing gas turbines. Don't get me wrong, I don't like it, but it's definitely easier and quicker than something on the scale what would be required with solar. Long term yes the solar/batteries would be cheaper.
Edit: i fail at addition and addrd storage and solar for the solar. 7GW + 7-10GW is not 23 to 26. So itd be 14 to 17x not 23-26x.