[ianburrell]

Many of those extra things can be intermittent and shut down when excess power isn’t available. Which means can overbuild solar and wind to satisfy everything but the worst case, and use the excess most of the time.

The result is that don’t need seasonal storage only daily storage. It is likely better to build more capacity than long-term storage. Although, generated fuels like hydrogen might work well for long-term storage.

[Equadex]

Production facilities idleing is not free. Intermittent production means the equipment isn't generating any money while costing the owner money. Wheter this is significant depends on the cost of the facility, economic yield from production and if costs are energy dominant or not.