Sorry, I should have more diligently expanded my abbreviations... B^>
Rgds
Damon[ Parent ]
At someone else's prompting, total cost about £28k for PV + £6k for ASHP as opposed to just £6k for solar DHW, but none of those figures is firm.
28000 - 6000 = 22000 = ballpark difference in cost 22000 * .05 = 1100 = annual interest in British Pounds at 5%
if the maintenance and depreciation were identical it still seems unlikely that you would save even 550 Pounds on energy costs - or on difference in income on energy generated per year assuming a home energy use on a home about like mine. $1100 U.S. is about 5500KWH at $.20 U.S. per KWH which is a bit less than double what I pay per additional KWH now.
Another way of looking at it is that you would need a difference of about 15KWH average for every day of the year (at 20 pence per KWH) from the ASHP system to come close to competing at those costs. This of course excludes any government or other incentives and of course assumes equivalent maintenance and depreciation.
Still it is interesting to see how close to self sufficient one can come energy wise in an urban environment. Rich'A Joule saved is a Joule made'[ Parent ]
Saving money is no part of the motivation.
Reducing carbon footprint, preferably to (say) current Chinese per-capita levels, is.
Now, there is probably a very large emboddied energy in the ASHP that I don't (yet) know about, but at least the refrigerant is sane in the models I'm interested in.
I see I used 'costs' misleadingly in my opening line: my apologies.
I meant costs in the CO2-costs sense.
There's a decent prospect of the PV side getting much cheaper, soon, but I have no idea about the ASHP until I do more research.
Still, if 1 million+ of the ASHP variants that I'm interested in got installed in Japan that sounds like maybe 1%+ of households already, and some of these systems are as cheap as £500 here (maybe $500 in the US) and thus compete with ordinary boilers/furnaces.
So really, the silly bit is putting the RE on my own roof, and if you take that away you discover that lots and lots of people, especially in Scandinavia, where power is cheap and clean and heating is difficult/vital, have these heat pumps already.
So the foolish and expensive part really is the microgeneration, and maybe an understanding of the value of CoP, and trying to do it all in a house built to rather less good insulation standards than the typical target of a heat-pump install until now.
You think that'll deter me? B^>
But it might well be worth trying it with a cheaper unit. At worst you get CoP of 1 and you're back to an expensive resistive load.
Would you use an air-to-air or air-to-water pump by preference?
Damon [ Parent ]
The main difference in an installation I would have would be the power source. I would have to add a second inverter and connect both in a stacked lbx mode to power it. I have one SW4048 connected to one phase now which works out OK, so I know that the concept is sound. It would draw power from the renewable source when available, and from the grid when not. I would leave the resistive dump load in place as a failsafe.
Of course this would depend upon my ability to expand my rooftop solar arrangement. I hope to add 6 more 190 Watt panels this summer. Also, I will need to expand my storage. I currently have a 440 Amp hour bank at 48V only.
Like you my main goal would not be the economics, but the reduced consumption. Rich 'A Joule saved is a Joule made'[ Parent ]
