Shutting down factories in winter will make local industry uncompetitive, which will have awful effects.

That argument ignores the fact that the variability goes both ways: during peak production times, electricity will be CHEAP. Hell, it's not hard to imagine a situation where capacity gets built up high enough to extend the viable high-consumption times that during peak hours the grid has to actively incentivize industry to use more power.

IMO, the right move is for the government to subsidize power generation to the point of absurd excess, like we do for agriculture. It's a matter of national security, and it ends up acting as a subsidy for industry of all kind.

Yes, you can make extra cheap aluminium on sunny days, but when it's cloudy you have a bunch of metal workers with nothing to do.

Aluminum pots cannot have their power varied too much. Either they freeze up or they ruin the walls by overheating. Some variably can be tolerated, and would be useful, but they wouldn't be highly dispatchable like electrolysers would be (and are not at a scale that could load balance entire grids.)

Brownouts and blackouts lasting for weeks during windless winter weeks are hardly solution.

Can't we fill the Sahara with solar panels? If transmission lines are problematic hydrogen or methane could be used to transfer the energy to where it needs to be used.

This of course has a lot of political implications, but if we wanted to do it we could.

And quite avoidable, even on a 100% renewable grid.

I was responding to " So make the factory, AC, etc... vary the load! " that proposed blackouts as solution.

That post did not propose blackouts as a solution.