"The number of hours with negative power prices in Germany increased by around 50 percent to 146 hours in 2017, which translates into 1.6 percent of total time"
So if you're only going to run it when power costs are negative, you're amortizing the capital costs over running the plant for the equivalent of six days a year in 2017 Germany.
This is changing rapidly in many countries. House and large farm PV is getting super popular, more wind generators are being built, etc. Wind grows 10+% every year in Germany and solar ~5%.
I agree it's going to change. Overprovisioning of renewables is going to be necessary if we're going to rely on them alone, and long term I am excited about hydrogen.
But parent's link didn't really back up their claims, and concerns about capital efficiency for infrequently used plants are valid.
So if you're only going to run it when power costs are negative, you're amortizing the capital costs over running the plant for the equivalent of six days a year in 2017 Germany.