Any FCEV has a battery that in theory can be charged from the grid. So FCEV owners are also interested in charging their cars at work.
Making grid electricity with hydrogen is expensive, but is only need for a fraction of the time. So on average you come out ahead.
There may in the future be an interesting difference in regions. Some regions can combine hydro, wind, solar, etc. and have cheap electricity. Other regions are not so lucky.
Plug-in FCEVs exist. They can react flexibly to energy costs if hydrogen suddenly gets more expensive. They make more sense than a car that only runs on electricity.
If by "fraction of the time" you mean upwards of 100% of all grid energy for weeks on end, then yes it is a fraction of the time. In reality this is such a large factor that it will drive hydrogen costs to below grid electricity for very long periods and over large areas. Some communities might even think of getting off the grid and generate all electricity from hydrogen directly. In such cases hydrogen will always be cheaper.
While it will make sense for some communities to stick with direct electrification, this is going to be the rare case where dependable renewable electricity exist. It will also likely force BEVs into driving "islands", as it would not make sense to drive a BEV outside those specific regions. Ultimately, BEVs will end up mostly as commuter cars intended for short range trips. This will also drastically reduce the problem of battery e-waste and eliminates the need for vast numbers of fast charging stations.
Solar panels are cheap. Batteries are cheap if you can use them every day. Indeed not everybody has a drive way.
Weeks on end sounds very dramatic. But the important number is what fraction of the year. Combining solar and means that a very large fraction of the year there will be green electricity.
If you need to produce large amounts of green hydrogen, then you need to massively overbuild green electricity production. And this increases the fraction of time that there is green electricity.
With respect to islands of BEV. That is a bigger risk for FCEV. It is very unlikely that a BEV island would have a hydrogen infrastructure. On the other hand, in an area dominated by hydrogen, it is still cheap to provide a few fastchargers. Maybe the elctricity won't be cheap but the charger setup is not that expensive, so you can expect them on major highways. Which will make FCEV the car for commutes.
In any case, I'm curious which country will actual role out a fine grained network for green hydrogen. I very much like to know what green hydrogen will cost 'at the pump' if there are no subsidies.
It will be a significant fraction of the year that will be powered by hydrogen as the primary energy source. Just creating more green electricity will mostly end up wasting it as there is no other way of capturing and storing it.
All regions must have hydrogen available. For things like industry, shipping, trucking, grid energy storage, etc., it is basically unavoidable for a country to not hydrogen. BEV islands will be small and not an alternative to widespread deployment of hydrogen-related infrastructure. But the reverse is not true, as it is fully possible for a country to reach zero emissions with no BEVs.
The biggest change in environmental policy is the widespread deployment of hydrogen and related technologies. Many countries now like the UK, Germany, Australia, Japan, etc., have very significant hydrogen expansion policies. These policies will accelerate rapidly going forward.