Batteries are deployed quickly, but high-capacity grid connections can take a decade in the planning phase alone. Everyone wants one, and NIMBYs are quick to oppose them. Locating at a decommissioned nuclear plant is a great solution avoiding this issue
Recently had a battery storage facility nixed near where I live because the loudest local residents were panicked about possibilities of leaks of heavy chemicals into the groundwater (which is somewhat fair) and a bunch of less reasonable nonsense. Still, assuming the legit risks can be handled, facilities like these are crucial to future growth in electricity demand.