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Solar PV & ASHP might beat solar DHW | 20 comments (20 topical, editorial)

Re: Solar PV & ASHP might beat solar DHW (3.00 / 0) (#19)
by DamonHD (d@hd.org) on Mon Jul 7th, 2008 at 11:12:25 AM MST
(User Info) http://www.earth.org.uk/

Depending on what duty cycle you have that might be an expensive replacement for the resistive heating, and you'd have to be careful to avoid short-cycling the pumps.

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?

Rgds

Damon

[ Parent ]

Re: Solar PV & ASHP might beat solar DHW (3.00 / 0) (#20)
by richhagen (richhagen (a t) Juno.com) on Mon Jul 7th, 2008 at 02:54:45 PM MST
(User Info)

Currently the main heating unit is a forced air natural gas unit. There is an A-coil for air conditioning which I put in at the time and ran the lines out from the finished apartment. I never installed the AC, but the refrigerant lines are still in place and should be appropriately sized for a heat pump as well. I was looking at something like: http://www.djsonline.com/amanaasz18_heatpumps.htm (but probably in a smaller 1.5 or 2 ton capacity.
I am not an expert on these, but understand the basic concepts. I basically would likely need to change out the A-coil and get a control that would work in conjunction with the natural gas heating and the available power source to optimize the efficiency of the heating. Such controls have been commercially available here for such systems but I am just starting to look at this so much more research is in order. I would likely need to be able to modify the control to take into account the state of the battery bank.

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 ]

Solar PV & ASHP might beat solar DHW | 20 comments (20 topical, 0 editorial)

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