Which is going to be hydrogen, not charging from the grid, for long stretches of time if not all the time. The cost of solar panels plus batteries will add significant cost and make it less cost effective than large-scale production of hydrogen. Not to mention that only a minority of people will have access to this.

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.