On 01/14/2015 11:39 AM, Ben Goren via EV wrote:
I hadn't heard of heat pump water heaters before this discussion.
Something like that could, indeed, tip the balance.
What happens to the cold side of the heat pump? Can that be used to
reduce air conditioning load in summer?
Certainly, depending on where it's located. Mine is in the basement
where, unfortunately now, it's keeping it quite chilly. It was 56 down
there yesterday. But in the summer it helps keep it cool and helps
dehumidify it. I have a dehumidifier that runs almost constantly all
summer. The water heater generates about 5 gallons of water every 2
weeks so that's got to be helping.
As of a few years ago, the return on investment, the payback time,
for solar hot water was better than that of PV -- and that included
maintenance every few years, electricity to heat the water on cloudy
days (though much less electricity since you still get a substantial
amount of warming), and so on.
But it's obviously a rapidly-evolving field. If heat pumps really are
coming to water heaters, that's huge not just for PV adopters but
energy efficiency across the spectrum.
Absolutely. My GE GeoSpring has a 2.4 energy factor. (You can also buy
stand-alone heat pumps that you plumb inline with a standard resistance
water heater.)
I think, as others have said, that the plummeting price of PV has really
tipped the scale and when you add in the improving efficiency of heat
pumps it really falls over.
--Rick
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