To get $2/kg 300 bar H2, $500/kw electrolyzer capital costs, and 2c/kwh electricity input costs are needed. China is pushing down to $300/kw on electrolyzer costs. Just as seasonal negative prices happen in some locations, stabilizing to 2c/kwh is the path H2 enables. $2/kg H2 means 6c/kwh CHP power cost from Fuel Cell, and 10c/kwh electric only power output. Competitive with electric utility service, and fast charging vehicle stations. It's competitive at $4/kg in many jurisdictions, in fact.

Factories already operate mostly daytime. Solar output is seasonal with more variability the further from equator you go. Having solar cover 100% of summer cloudy day generation at low AC use, can result in 2c/kwh or less prices on sunny days, and in Spring and fall where there is no HVAC demand. Running FF electricity just in winter/backup is path to significantly lower emissions, and lower cost of FF energy from less use. Factories with long shifts running half on solar is still low overall energy input costs, if they can sell what they make.

H2 storage is a solved problem. Lined pipe and pressure vessels. If factories are ever automated to the point where labour cost is nearly irrelevant compared to energy costs, then they too can become variable loads. H2 electrolysis and desalination and battery charging are all highly automated processes that benefit from those conditions today.

The forever advantage of green H2 production is that it is containerizable. Can be transported seasonally to where renewable surpluses will occur. I guess self mobile robots could do the same, though.