I don't know how many hours would your mining go every day (probably @philipma1957 will come with the proper math), I think that it makes sense only if it's more than 2-3h
20kwh flat a day assuming no extra spent on anything as cooling would be able to run him an S19Pro for 6 hours a day, just a little bit more with an S19XP, but I would not let it go for more than 5 to be extremely sure some other thing in my house will not push the consumption over.
But let's stick with the 6 since it's easier for math, 1/4 of a day.
Standard bitmain shop prices, no taxes, a 19Pro will get you 2.5$ a day, so it will take about 1800 days to make for the miner, the S19XP will do 3.5 and I remember Mikeywith saying something of 8k for one, so 2200 days.
I have net metering and if I don’t use my excess the power company uses it for free.
I assume that in your contract is stipulated how you can use your extra energy, I don't think that any company has written there it must be exactly the same quota each day, so you could simply let it run for one week continuously and then shut it, less stressful for the miner and for yourself. I agree with DaveF, get one older generation used miner, less revenue but at least chances of actually making a profit, that is...if the miner doesn't break. Let's see if somebody is up to date with used gear prices, as I have like zero idea where those are right now.
