Changing times

I don't disagree that currently the best storage option is Li. However, it is also my personal belief that the long-term solution will be a much more distributed storage and generation scheme. At present, most utilities are heavily invested in selling power, and not their distribution system. It is the primary reason that solar grid-tie is such a big issue all over the country. If they can change their mind set, and start charging for distribution in some fashion, they might be much more receptive to distributed storage and generation.

Here's the answer we've been looking for.

Grid energy storage using elevators in skyscrapers, with robots storing wet sand ballast in the corridors. And the robots will be programmed to get out of the elevators if ppl need to use them.

Skyscraper energy storage.

not satire, apparently. someone spent quite a lot of time looking at this.

Here is a link to the researchers published study

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Lift energy storage

My thought is that post Covid everyone wants to work from home anyway. So why not just vacate the top half of all those high rise office buildings and use half of each building and half the elevators for energy storage? That still leaves half of each building for human use, let the robots and sand have the rest so nobody's feet need to be run over.

From what you describe as the energy profile of conventional cable based counterweighted elevators, it sounds like the skyscraper storage concept would work much better with the cable-less Thyssen maglev elevator technology the article refers to. The only problem I guess is it costs 5x what a normal elevator costs. But it can go sideways as well as up and down.   Willy Wonka anyone?

As for a solar elevator, it's going to be better to just grid tie the solar instead. That way none of the energy is wasted when the batteries get full and elevator usage is low, it can get used elsewhere in the building or by other grid customers.
Same problem happens with solar powered EVs, better to put the solar on the roof and grid tie it rather than on the car itself.   

I was kidding about the Thyssen Wonavator.

It's not a day/night problem, batteries do take care of that. It's a summer/winter problem. Trust me I designed these systems for a living for 40 years.

Off grid solar is never anywhere near as efficient as grid tied because of seasonal solar insolation variation. If you size the PV array for winter operation when the available insolation is low you will waste the excess energy production in summer to avoid battery overcharging. There is no way around that unless there is another place for the excess production to go, eg the grid. To do it with batteries you would need to install enough battery capacity to carry the load for smany months, which is totally cost and resource prohibitive.

This is especially true in a northern climate like Europe where ppl tend to be most interested in this kind of thing. In northern Germany there is more than a 5x difference between June and December for example.

So the Schindler solar elevator is going to appeal to architects and building owners who want to appear to be green more than they actually are green. If they really want to be green they'll install a conventional grid tied solar array and a conventional grid connected elevator system. As with Thyssen's Wonkavator, Schindler's off grid solar elevator sounds really cool but makes no practical sense.