I found that over the years, the bottom line correlates pretty well with
total energy concerns. I got away from DC and other super energy
efficiency modes, as reliability is even more important, and non
standard pumps just don't last near as long. For off grid, I usually
spec Grundfos SQ
Why would one specify DC voltage appliances or lighting for off grid systems
today when we have sub-buck-a-Watt PV solar power? If you have space, you can
make the added power that conventional AC appliances draw for very low cost. It
could even be argued that the cost for DC items, wiring,
-boun...@lists.re-wrenches.org] On Behalf Of Larry
Crutcher,Starlight Solar Power Systems
Sent: Tuesday, December 11, 2012 11:56 AM
To: RE-wrenches
Subject: [RE-wrenches] DC, or not DC, Dat is Da question (Two Load
Questions)
Why would one specify DC voltage appliances or lighting for off grid systems
--
*From:* re-wrenches-boun...@lists.re-wrenches.org [mailto:
re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Larry
Crutcher,Starlight Solar Power Systems
*Sent:* Tuesday, December 11, 2012 11:56 AM
*To:* RE-wrenches
*Subject:* [RE-wrenches] DC, or not DC, Dat is Da question
The light by the inverter is the only DC appliance I routinely recommend
nowadays in off grid homes and businesses, unless they have no backup
generator. If no backup, every electron counts, and there are some DC
appliances, in that case, that can be worth the price and fuss.
Blessings,
Kelly
Hello Larry,
I still install DC fridge/freezers in off grid systems for efficiency, but
also so that when the owners leave for the weekend/week/month they can turn off
the inverter and all the associated phantom AC loads, but the DC freezer is
still on. When they come back, the meat in the
I'd do the comparison against one of the much cheaper energy star rated
AC models. In my comparisons,On the slight edge in efficiency isn't
worth the extra cost of the DC units. I've also had premature failures
of DC fridges due to low voltage. Finally using the inverter's built in
low
Hi Jason,
With respect to you, Sub Zero is an exceptional refrigerator but at 4-5 times
the cost of conventional high efficiency refrigerator so the cost comparison is
not really relative to most peoples choice.
A typical efficient 25 cu ft refrigerator will draw about 400 kWh annually.
this brings up a probably off topic subject regarding efficiency. i have always
considered efficiency and conservation to be job one... especially on off grid
systems... but with modules so inexpensive... does this still make sense? for
example, i have an off grid customer who i suggested get
Conservation = doing without it.
Efficiency = doing it but using less energy.
We really always try to avoid specing any system that's DC only, but we get
some pretty unusual requests from remote regions.
The Morningstar SureSine inverter has made most DC system designs moot. But
not all.
Dan
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