[RE-wrenches] DC, or not DC, Dat is Da question (Two Load Questions)

[Ray Walters]

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, toddcory at finestplanet.com 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" <larry at starlightsolar.com> 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*
> Allan at positiveenergysolar.com <mailto:Allan at positiveenergysolar.com>
> 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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