Even if the marginal cost was zero, you gave coal/nuclear as the cause for negative energy prices, even though they didn't exist before renewables came into the picture. You may claim that the situation is better with the renewables in the mix, but you can't claim that renewables aren't the ultimate cause of negative prices in this case.
Similarly, you may claim that coal/nuclear are slow/expensive to regulate, but then must also concede that wind/solar can't be regulated up at all and couldn't provide a stable supply without e.g. natural gas, or a buffering solution that currently doesn't exist (at scale) and isn't priced into wind/solar.
Please provide a citation that renewables have a non-neglible marginal cost.
> Furthermore, if you pay negative prices as a result of a renewable surge, that might as well be considered into the marginal cost.
With a lot of imagination.
> couldn't provide a stable supply without e.g. natural gas
Alright, we'll keep those nuclear power plants that run on natural gas for now.
> or a buffering solution that currently doesn't exist (at scale)
We've got a way to build things that don't exist yet. It's called "engineering".
Riddle me this, then: Why did negative energy prices emerge along with renewables[1]?
The problem isn't coal/nuclear, because the variance in demand is far lower than the variance in output of renewables. Furthermore, both coal and nuclear plants can be adjusted to react to seasonal variance.
[1] https://www.cleanenergywire.org/factsheets/why-power-prices-...