It can be useful for transport or in some industries like steel industry where the alternative is burning coal or LNG.

And not all the solar fields and power plants are in use during the day. Some power plants like nuclear fission reactors can’t stop and relaunch that easily so they are used as the base, while renewables and gas are used according to demand because demand and power production have to be the same. So there are literally moments when solar and wind farms have to shut down during the day bc there is not enough demand for electricity. Using those timezones to produce hydrogen would be a good business