[xxpor]

That usually is true if your electricity is generated by natural gas too and you're comparing it against a gas HWH

Rough math is

NG -> Electricty is 50% efficient thermally.

A heat pump can have a COP of 4.2.

100 * .5 * 4.2 = 210% efficient, thermally

A hot water heater powered directly by gas is ~100% efficient thermally.

[kkfx]

Personally I do not care about efficiency: I can't sell energy I produce so the point is just heating the water and the load profile of a classic resistance and the load needs of my houses match normally to heat without the heat-pump (witch have a far limited life respect of a classic resistence)...

I use the heat pump mode only when there is little solar for few days where there is not enough overall energy production, otherwise being able to produce 120-130% of the overall consumption (of course ONLY when the Sun shine, so NOT independent as some sell just playing with absolute numbers) why care about efficiency? I can't use the extra energy anyway...