Solar Minisplit Hot water Heat Pump
I’ve been on vacation last couple weeks, so usually I get future thinking more than usual.
Minisplit DHW isn’t really a thing yet in north america, but I know it’s coming. Probably sooner than we think.
PV augmented heat pumps are also not really a thing in north america yet. But I know it’s coming. Probably sooner than we think.
But, thinking the way I do, I wonder what the viability of incorporating that into a residential hot water system would be.
Looking at fujitsu’s waterstage catalogue ( https://www.fujitsu-general.com/shared/pdf-feur-support-ctlg-3ef023-2008e-atw-01.pdf ), one of their single stage “super high power” units supplies 16kw (54,594btu) of heating, obviously in ideal conditions. That’s about a quarter of capacity of the 199kbtu unit I like to use.
BUT the concept of using a PV panel to provide ‘free’ water heating is interesting.
There’s some caveats here, for instance these have an electric resistance backup heater. Which I’m obviously not interested in when I live in Ontario, the land of cheap NG. Another is how minisplits are roughly a COP of around 3 or 3.5? Comparing that to my matural gas prices it’s cheaper to run gas, but I believe it’s relatively close.
So for a thought experiment, I’d like to ask the group here what they think of a potential setup:
PV split water heater, with it’s integral buffer/battery tank, and it’s backup electric resistance disabled, then to a 199kbtu NG tankless water heater plumbed in series.
Basically the concept is the heat pump water heater provides ‘free’ hot water when available, then the rest is made up by the NG heater. Used for both radiant heating and DHW.
Obviously in real life this would also have to take into account what a PV minisplit HW system would cost to a brand new market, and then when the ROI happens would have to be taken into account. Or reverse calculating where the system cost would have to be to start getting ‘free hot water’ after say 5 years.
Anybody have thoughts on this?
Here’s hoping some of you with more experience with the numbers or these systems can chime in.
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