[0] https://www.cleanenergywire.org/sites/default/files/styles/g...
[1] https://www.cleanenergywire.org/factsheets/germanys-energy-c...
(note: "levelized" costs are total costs divided by total real-world production, so it's already adjusted for "the time the sun doesn't shine" etc: https://en.wikipedia.org/wiki/Levelized_cost_of_energy
That metric ignores how much real world economy is being enabled by the power that you generated, roughly the price for which you could sell your energy in a free market.
My point would be that energy is much more important when the sun is not shining, etc. that makes e.g. solar not as good as a naive calculation would say. That sould be accounted for right?
I think that currently if you are capable of producing electricity but no one needs it, you get curtailed, and your "theoretical production" doesn't get counted towards your levelized cost.
What really needs to happen is for there to be good ways to store that otherwise-wasted energy (opportunity). Flow batteries are a promising technology for grid energy storage, as are power-to-gas and power-to-ammonia systems.
As you say, the inflection point for that economic effect was probably years ago in a lot of places, although if the world had made an economically rational coordinated response to climate change 40 years ago, it could well have made sense to mass-produce nuclear power stations and use the excess energy for atmospheric carbon capture.
To me that means that the "levelized cost" metric punishes controllable energy sources unfairly for the "issues" that are caused by volatile energy sources right?
Perhaps a better way to look at it is that there are two markets: one where providers compete to offer the cheapest power, and one where providers offer guaranteed amounts of power.
Once inter-day storage is deployed at scale, the providers in that second market might only be called upon 20% of the time (to pick an arbitrary number), but even if that means their costs are 5x higher than renewables, that might still be a price worth paying to ensure people continue to have electric heating during cold still winter nights.
I think the real outstanding questions are how far energy storage and over-provisioning of renewables can take us. For some people, charging a battery in their car or home during the day and half-draining it over night will mean they are self-sufficient in terms of storage for most of the year. On a wider scale, at certain prices it might even make sense to extract CO2 from the air and use renewable energy to make renewable natural gas.
It is not a cost/efficiency that is attributable to the inherant characteristics of the backup source.
That would be like blaming a relief pitcher for what happened in the innings he didn't pitch.