"data centres operate 24/7 with an industry standard of “five-9s” reliability—99.999% uptime, equivalent to less than 5.3 minutes of downtime per year. This level of reliability requires access to a stable and highly reliable source of electricity."

https://www.oxfordeconomics.com/resource/the-rising-challeng...

Many kinds of renewables are day/night, weather dependent, you don't get this level of reliability without a fossil fuel backup. If you already need to build a dedicated gas power plant to power your data center, then the decision to invest in an additional renewables power plant depends on the costs of the natural gas. (Additional capital expenses of the renewables power plant vs reduction in consumption of the natural gas).