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 pumps, as they are fairly standard, but don't have a
starting surge.
People won't appreciate the efficiency much when they have to replace it
in a couple of years.
If they're off grid, they're main focus can't be embodied energy, as
they're probably driving a SUV long distances every day. Also,
batteries are pretty bad, when compared to a grid tie PV system. I
studied my energy usage overall, and found that off grid wasn't saving
the planet, when I was driving 20K miles/ year. I moved into the city,
fixed up an old home, and ride a bicycle more. My overall foot print is
less than building a new "efficient" home out in the vanishing wilderness.
I've tried it all, and that's just where I landed for now. I'm
currently working on an off grid PV charging system for a customer's
Chevy Volt, though, so I'm always open to new things.....
Ray Walters
On 12/11/2012 10:10 PM, [email protected] wrote:
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 a lorentz pump for his well. yes, the well
produces around the same gpm as it used to, now only using about 15%
of the power... but the cost to accomplish that was absurd, and that
money could have been invested in more modules, which would also mean
less winter generator run time... but manufacturing modulesis not
light in the resource consumption department either.
so my question is: do you other wrenches just look at the bottom line,
short term costs for more efficient appliances compared to more
modules to power the old inefficient gear... or do you take the added
step to include embedded energy... and if so can you share the
calculation process?
thanks,
todd
On Tuesday, December 11, 2012 10:55am, "Larry Crutcher, Starlight
Solar Power Systems" <[email protected]> said:
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, distribution gear and labor will cost much
more than simply adding more PV solar and staying all AC.
I don't like wasting resources and I understand old school thinking
when PV modules were very expensive, but with high efficiency AC
appliances and low cost inverters and PV modules, does it still make
any sense? Shine some light on my thinking.
Larry Crutcher
Starlight Solar Power Systems
On Dec 10, 2012, at 9:12 PM, Allan Sindelar wrote:
Wrenches,
We still try to encourage prospective off grid customers to do a full
load analysis as an initial step in the system design process. To the
point:
1) What is a good watt-hours/day figure to use for a typical, modern,
new, carefully chosen, fairly large conventional AC chest freezer, if
kept in a heated indoor location? Assume 65 degrees and seldom opened.
I will encourage that the freezer be located in a shaded, protected
outdoor location, in order to greatly reduce winter energy
consumption, but I need a good base figure to work with.
The proposed system will most likely be 48Vnom, so a Sundanzer or
similar DC freezer is out.
2) Same question for a ceiling fan, for general slow circulation of
winter heat. The energystar.gov <http://energystar.gov> list gives
relative cfm efficiency but not wattages. Is 55W still a good figure
to use as a default?
I have attached a condensed energystar.gov <http://energystar.gov>
list for the freezers, but wonder what other off grid Wrenches
typically use. Also, I'm not sure that Wrenches posts allow
attachments, so this may not appear with my message.
Thank you,
Allan
--
*Allan Sindelar*
[email protected] <mailto:[email protected]>
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
*505 424-1112*
www.positiveenergysolar.com <http://www.positiveenergysolar.com/>
*
*
<Freezers Product
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