Producing hydrogen when there is excess power from renewable source could be a great addition to the mix of "how to store energy when we produce more than we need, and use it when we need it".
but the biggest problem is psychological: The Hindenburg, still
So it's only worth it if you have other uses for the hydrogen or need longer-term storage, e.g. gas reservoirs.
Plus any infrastructure you build will have to be overprovisioned because by definition it'll be designed to absorb peaks and run idle the rest of the time, which makes it even less profitable.