Everybody can run their AC's full blast with the windows open.

I think this approach, just massively deploying an overbuilt capacity of solar, really is the future. There are a lot of things you can do with excess power. For example, with enough overcapacity, you don't have to worry about seasonal variations. A solar panel even on a cloudy day in winter still produces some power. If you build enough panels to meet your peak demand on a cloudy winter day, then you really don't have to worry about seasonal variations; only day-to-day variations.

That gives you a ton of excess energy to use during the summer months, but we've always found ways of using excess energy when it's available. Some things we could do:

• Carbon capture

• Synthetic fuel production

• Vastly cheaper aluminum smelting (and other metals where the ore is abundant, but the refining takes a lot of energy.)

• Large multi-story indoor vertical farms. (Vertical multi-story farming is often seen in sci fi, but real indoor farms tend to be confined to single-story greenhouses. This is because there's only so much sunlight available in an area. But with cheap/free energy at peak times, the energy problems disappear.

For the daily swings, even beyond moving energy long distances across a few time zones, there's a lot that can be done to move more demand toward the peak times. For example, homes can be built with better insulation and thermal mass. If a building is constructed with this in mind, it is absolutely possible to have a building that only needs heating/cooling equipment running during the times when solar power is available. In the winter, you use heat pumps powered by cheap solar to heat the building to a bit above the preferred temperature. When the Sun goes down, the heater turns off, but the building has enough insulation and thermal mass that it's only cooled to a bit below comfortable temperature by morning. You can do the same trick with fridges, freezers, water heaters, etc. For washers and dryers, they can be built to give you options. If you want something washed right now, even at 11 PM at night, you can do so, but more for electricity. If you're not in a hurry, you load your laundry and have the washer/dryer simply wait until the Sun rises and drops the spot price of electricity.

I think we have far more potential to shift electricity demand through a day than we give ourselves credit for. We're not used to thinking this way, because we're accustomed to a world where the cost of electricity is constant throughout the day. Batteries and other methods like thermal storage, compressed air storage, etc will always have their place. But I think we can probably eliminate 80-90% of our need for storage to meet daily swings just by being a bit more clever about when and how we use energy.

Hell, I could even think of a way of using thermal mass for something like cooking/baking. Many traditional stoves were built with a ton of thermal mass. Things like this. You could have an oven that was a box surrounded by a ton of insulation and thermal mass. It uses solar power during the day to heat up to say, 350F and then just retains that heat all evening. If you need to cook something in the evening, you just pop it into the already-warmed oven. If you need a temperature over 350F, you use a small bit of expensive evening energy to drive the temp up a bit hotter.

Sure, this seems like a gluttonous waste of energy in a contemporary context. But if energy is superabundant and essentially free during the day, then things like this become possible.

That would only work with lots of HVDC cables. In fact if we could produce our electricity about 2 times zones to the west and bring it to the place of consumption by HVDC cables, we could match the demand almost perfectly.
And if we can go 7 times over then I would suggest going for hydrogen or better synthetic fuels. That way we could even store enough renewable energy for the winter and the relatively huge losses would be worth it.

This I’ve heard in relation to electric cars in particular. Countries with a strong car culture have tons of batteries that at any given time are either idle or being used for low-energy applications like music, gaming, or cooling (cars are much smaller then even tiny apartments).

No amount of over capacity makes the sun shine at night or during a winter storm.