for someone who started out demanding that people 'please provide' a 'source for reliable figures', your comment is astoundingly devoid of any sources or indeed factual information. you are very much not living up to the standards of debate i was hoping for; please try to do better

> "Not producing maximum power because it isn't needed at the moment" is an entirely different thing from "not producing maximum power because you can't".

your replacement solar plant also doesn't have to produce the un-needed power, so you have to take the capacity factor into account when you're calculating the replacement size

> No storage costs are mentioned [in the article about the palo verde trading hub prices]

yes, that's why other parts of my comment explore storage costs in great detail

> Most places are not New Mexico

most places that people live are sunnier than new mexico or close enough to someplace that is

> there's some heavy government subsidization involved here

yes, you may note that the comment that you're replying to discusses those subsidies and actually names another one and computes what the unsubsidized cost would be for your suggested 2/4/1.2 gigawatts. as i mentioned, there's also some heavy government taxation involved here; solar panels in the usa cost twice what they cost in the rest of the world. also, as i mentioned, the price of solar panels has dropped by half since the article was written

> you're claiming ... because there are still coal plants

technically what i claimed was that the typical number in practice was 3–4 hours not 'because there are still coal plants' but 'partly because there are still coal plants and partly because electrical demand drops a lot at night'. probably i should also mention wind power, nuclear plants, hydroelectric power, gas peakers, and distributed storage such as car batteries, all of which currently play a role in compensating for the intermittency of solar

the current average is about 3 hours; that will presumably increase as solar becomes a larger fraction of the grid. to estimate how much it increases, we need to start by understanding the current situation, but we also need to predict how extensive demand response will be. you posit that the storage requirement will increase to 12 hours, but that seems unlikely to me. if it did increase to 12 hours, that would make the battery system cost as much as the solar farm. unless batteries somehow got cheaper

what's at issue is not 'freezing in the dark'. people generally do want it to be dark most of the night, because they're asleep, so not being in the dark only requires storing about 40 watt-hours per person, which is a single usb power bank. and you can reliably avoid freezing with a so-called 'sand battery'; 12 hours of 6000 watt heating can be provided by a tonne of sand heated up to 250° when the sun is shining. that's about fifty bucks of sand and a few meters of nichrome wire. if you live in a normal sized house with maybe some insulation you need a lot less than that

so relax, you're not going to freeze in the dark

a mean man scared you with a scary story, but it's not real

rather, what's at issue is industrial process plants like blast furnaces and haber–bosch nitrogen fixation, which are traditionally pretty intolerant of being shut down; it takes a long time to bring them back to steady state after a perturbation. in some cases there are alternative batch processes that compete with continuous-flow processes, which have conventionally been economically uncompetitive, though there are exceptions such as electric arc furnaces. in other cases, it may be possible to design continuous-flow process plants in such a way that they can ramp up and down efficiently, so that they can take advantage of the unprecedented abundance of free energy during the daytime