Because these are bad comparisons, a heat pump water heater and a heat pump house heater use substantially less electricity. Resistance heating sucks and will lose to burning gas locally.
Speaking for myself (and I suppose the millions that are on the same utility), the only time when it's cheaper for us to use the heat pump over the gas furnace is from midnight to 6am and when the temp outside is below 20F.
You're also assuming time of use billing, I assume.
I don't disagree, btw - gas is cheaper than a heat pump for me also, which makes me sad. My only point was that you have to compare against them and not resistance heating. (That's slightly wrong - if I were to use a heat pump during the shoulder season and my boiler when it's colder it would be cheaper in operating costs but lose on capex)
Is that accurate?
They use a tankless water heater so electrical use is ~zero when nobody is using hot water, which is most of the time. If you use a tank - heating ~40 gallons of water 24/7/365 - that's hard to compete with by just being more efficient.
Is there such thing as a heat pump-powered tankless water heater? I expect the challenge is the surge of energy needed to instantly warm heating elements to functioning temperatures.
There are all-electric tankless water heaters but in my limited experience they need ~120A available, which is prohibitively expensive. (Why not just a capacitor that can surge the startup energy?)
Let's say you want to run a single shower at 2.5gpm, the water comes into the home at 55F (12.8C, pretty temperate!) and you want your shower at 100F (37.8C), so a 25C rise. 2.5gpm = 9.463 L/min = 158mL/sec. Water's heat capacity is 4.184* J/mL/degC, so the sustained thermal power you need to deliver is:
4.184 x 158 x 25 = 16.5kJ/s = 16.5kW
At 240V, 16.5kW would be almost 70A.
What makes a heat pump heater more efficient is that it multiplies the electrical power input into a larger thermal power output, by "borrowing" thermal energy from the surroundings. So you could get (for example) 15kW thermal power from 5kW electrical power. In practice the heater will be tanked, rather than tankless, for two reasons:
1. The effective power will probably be less than that.
2. That was an estimate to run just one shower and you might want to run more than that!
So the tank lets you buffer the power draw over time; there will be some thermal loss over time, but insulation is cheap, and it's hard to fight a 3-5x amplification from the heat pump.
* Yes, yes, per gram/K but 1mL of water is close enough to 1g for this.
FWIW, one US govt source attributes ~20% of a typical household's domestic energy usage to water heating, though the source doesn't attribute it to thermal loss or initial heating.
You need to compare this against the average heating days for their location.
Water heaters are a "incandescent lightbulbs are 100% efficient in the winter" situation.
The other issue is the for-profit electric monopoly. The elimination of gas will just mean they can extract even more from their customers.