Heatpumps to aid in heating hot water for a house is also a good idea if one’s neighborhood doesn’t have gas running through it. I would say that a heatpump would have a hard time heating water to 130 farenheit, so I think it would be best to be used to heat water in a secondary tank to 105 farenheit or so and then this tank feeds into the primary tank…

But this fancy technology costs $$$ I do admit!

If only the production and deliver of power to a home was more efficient …

“However, when the outdoor temperature approaches freezing, a heat pump’s COP can drop down below 1, at which time a resistive backup heater takes over.”

I like this article but I’d have to disagree on the facts you show on the quotes above.
I don’t know about heatpumps that are 15 years + older, but modern heatpumps, I would say still have an efficiency of at least 190% @ 32 Farenheit.
I am looking at a Trane Weathertron Heatpump datasheet manufactured in 2002 (10 seer, HSPf: 6.8 High temp COP:3.1 low temp COP: 2.0), and it is still 238% efficient @ 32 Farenheit, and 176% efficient @ 12 degrees farenheit! It loses about 50% of it’s capacity @ the 17 degree farenheit mark.

That is your standard efficiency heatpump …
and now heatpumps with Inverter Compressors (read: Variable speed) carry a large boost in efficiency. I just installed a Daikon 16 seer dual-zone unit .. according to the data, it will only lose about 1/3 of it’s capacity at 14 Farenheit, and is more efficient too.

So clearly heat pumps still have good potential as long as the winter in the climate it is considered being put in doesn’t go below 15 farenheit very often