That's a rather fat margin. And things would be a lot cheaper overall if we could shave that off with some long-term storage.
A 5x overbuild would give you massive amounts of "free" electricity. I'm sure the world would find something economically useful to do with it. Maybe you could use it to generate green hydrocarbons from atmospheric CO2, killing several birds with one stone.
Which would start to look a lot like long-term storage. But subsidized by negative energy prices during excess production. So rather than bleeding money while someone else makes profits any power company will prefer to build less overcapacity (which also avoids risking devalued assets) and run their own peak-shaving if they can. Which means this problem still has to be solved one way or another. Whether you call it long-term storage or excess energy use.
> generate green hydrocarbons from atmospheric CO2, killing several birds with one stone.
This is great because it means we can use guilt-free hydrocarbons where they're important. Like rocketry and airplanes, making lubricants, plastic bags, etc.
> overbuild would give you massive amounts of "free" electricity. I'm sure the world would find something economically useful to do with it.
Generating proofs of work for a blockchain collectible card game? :D
If nuclear power physics stopped working October to March, that would drastically effect nuclear power economic competitiveness...
Wait, what's this people are telling me, I can't just make stuff up?
You make up a completely BS example but then actually go through and try to come out with actual numbers. Right.
Yes, 5x variability in wind production has actually been observed: https://en.wikipedia.org/wiki/File:Erie_Shores_Wind_Farm_out... https://en.wikipedia.org/wiki/File:Windpowerprediction.png
There is no summer which have had no winds, no winters that have had no insolation or vice versa. Instead of making up numbers, you can use a site like this: https://www.solar-electric.com/learning-center/solar-insolat....
You'll find that by comparing seasonal best case to seasonal worst case it is something like, on average, 50% difference. It gets worse the closer you to get to the pole obviously.
Furthermore, surplus production does not go into dev/null. Excess resources create markets, and there will be consumers that take advantage of cheaper surplus power (smelting, heavy industrial, desalination, hydrogen production, and whatever else anybody cooks up).
The part of "no production" were not meant to be taken literally. If you want a more precise statement then let me put it this way:
For PV in central europe even an overcapacity factor of 5 would be insufficient to cover the difference between summer and winter. Germany's PV plants produced 7.3TWh during June 2019 and 0.58TWh during december 2018.
Wind does look a bit better as far as seasonal differences go (about 4-5x) but it suffers from more short-term variability, so you might need less seasonal storage for it but it would require more medium-term (multi-day or -week) storage compared to solar which is a bit less variable during its peak months compared to wind's peak months.
This leaves experimental solutions like the Sabatier process, Hydrogen storage, or more exotic things like lifting concrete cylinders with pulleys.