They don’t shut down entirely because the aluminum has to stay molten at a thousand degrees, but they can scale the energy usage significantly, this is becoming more of an interest in the last decade.

https://www.greentechmedia.com/amp/article/german-firm-turns...

When solar hits a certain ratio of production there will be a daily peak where electricity will be very cheap because there’s too much of it, regardless of what people “advocate”.

Electrochemistry things are where it’s at, metal refining specifically.

Aluminum production from ore has one step where you literally just make what is effectively an enormous battery out of aluminum ore and “charge” it, when it’s fully charged you’ve turned aluminum oxide into pure aluminum. It can even be run backwards to produce electricity because it’s literally a battery (a really shitty one). So there’s not a huge capital investment or complex process and electric input is actually a significant portion of the cost.

Other simple electrochemistry things that do have a major portion of the cost in electricity can do the same when costs get low enough. There’s a lot of recycling that becomes possible with cheap clean energy that you would never do with fossil fuel electricity.