[DennisP]

From that Lazard report, PV with four hours storage costs 10 to 13 cents/kWh. That's "in front of the meter" which is the wholesale cost. For retail cost, commercial/industrial pays 22 to 38 cents/kWh, and residential pays 45 to 66 cents/kWh.

That's with only four hours storage. That's a convenient amount since it's the excess typically generated by solar installations during the day, but to actually get through a windless night we might need more storage. Lazard's retail cost for storage alone is 48 to 104 cents/kWh. Plus you'll need extra solar dedicated to charging it.

At this point people often bring up long-distance transmission. The report happens to include that too, with a cost starting at $2.35/kWh wholesale and going way up from there.

None of this includes the overcapacity we'd need, to get through cloudy winter weeks.

Lazard puts nuclear's cost at 12 to 19 cents/kWh but it's unclear whether that's retail cost; I suspect so since I only pay 12 cents/kWh on a grid that's heavy on nuclear.

Wind/solar is very cheap when the grid is still mostly fossil, but to run a reliable carbon-free grid in areas without abundant hydro, nuclear is still cheaper. The cheapest combination is probably nuclear to the level of minimum nighttime load, and renewables for everything beyond that, without just enough storage to even out remaining discrepancies with demand.

[makapuf]

What night base consumption is absolutely vital ? I understand that some of the consumption is necessary to function and that some other is made possible by the fact that fossil energy is as expensive to generate at night and that it's cheaper to function 24/7. But sometimes it can be cheaper to shut down widget X factory at night not to double storage capacity. Maybe this effect will be important, I don't know.

[DennisP]

If we have to build twice as many widget factories to make up for shutting them down at night, that's another cost to society that we should take into account. I've seen a lot of renewables advocates talk about "demand management" but not any estimate of this cost.

There's also heating, air conditioning, street lights, etc. Aluminum plants, which can't shut down more than 4-5 hours without major damage from the metal solidifying.

Before long, electric vehicles charging in people's garages at night; it'd be nice if we used them to supply the grid at night but that would require parking lots full of charging stations where everybody works, plus new infrastructure in people's houses, and some kind of incentive to get people to bother. All that costs money too.