I'd 2nd Hilton's comments. Energy efficiency can reduce heating loads
to almost nothing. The German standard "passive solar" design uses
almost R100 insulation, triple pane Lo E windows, doors with multiple
seals, and are so tight they require an air to air heat exchanger to
insure fresh air. The occupants own body heat accounts for a large
percentage of the heating, and small amounts of passive solar gain do
the rest.
I've worked with a builder in Taos that is building to this standard,
and it works.
2nd, If that's too extreme for the customer, they can utilize an active
solar thermal system that works in conjunction with floor heating. With
efficient pumps and closed loop design, pumps only run in the day when
the sun is shinning anyway.
3rd, the old fashioned off grid method: air tight wood stove. No
electric load, and we have a lot of beetle kill firewood that is being
turned into CO2 by decomposition already. Might as well use it to heat
your home.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 2/4/2014 12:28 PM, Hilton Dier III wrote:
I've done a couple of load profile studies for heat pumps and solar
and unless the load is primarily air conditioning it's a bad match.
Ground sourced heat pumps in general only pencil out if there is a big
air conditioning load.
The only time I'd recommend a heat pump with an off grid system is if
there was a wind turbine that massively over-produced in the winter.
The PV production curve is exactly backwards.
The clients should take half the money they would have spent on
installing a heat pump and do a thermal efficiency/passive solar
retrofit. Better ROI.
Best,
Hilton
--
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC
453 East Hill Rd.
Middlesex, VT 05602
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