[RE-wrenches] How large is too large?

Mon Mar 2 18:08:18 PST 2009

Maybe they could go “off-grid” with a cogeneration unit powered by
biodiesel.  That could make a lot of $ sense depending on their annual
heating load and local kWh price.  Our local biodiesel plant sells it
cheaper then propane for now.  Rough math is 1/3rd electricity, 1/3rd
recoverable heat, and 1/3rd waste heat that you can’t get back.  You could
still take the some/most of the lighting, refrigeration and water pumping
off grid with large but still standard set of battery based inverters, wind
and solar.

Have you pointed out that batteries aren’t exactly environmentally friendly
and reduce the efficiency of the system?  That might trigger them to battery
less grid tie.

FYI, HUP now has a 1990 AH battery.   Of course that’s still way too many
stings to get to 19,000 AH (900+ kWh, wow)

Speaking of big, high quality batteries; Special thanks to Jamie Surrette
for helping me out last week.  I was able to successfully weld a new
terminal back on a Surrette 4v 1100 AH battery with his help.

Best,

Travis Creswell

Ozark Energy Services

   _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Monday, March 02, 2009 1:03 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] How large is too large?

We had a similar lead come up a year ago, although the lodge in this case
was 22 miles from mains power and 10K feet up.

Thank goodness we had contracted $3500 in design fees up front to do all of
the load projection and design research work. We determined that the
batteries were the limiting factor: at 48V, about 2,000 amp-hours, and two
or three strings max (depends on expected DOD), we couldn't provide a
battery bank large enough.

The only solution we arrived at was using Sunny Islands in 3 phase,
redundant generators, duplicate services, Sunny Boys on arrays, and Windy
Boys on two Provens to build an AC-coupled microgrid. That way we had
duplicate battery banks.

When we presented the general design approach to the owner's (common
household name, largest private landowner in the US) representatives through
the electrical engineer, with a preliminary estimate around $700K, they
decided to run the lodge on generators.

Allan Sindelar 
HYPERLINK
"mailto:allan at positiveenergysolar.com"allan(at)positiveenergysolar.com 
NABCEP Certified Solar PV Installer 
Positive Energy, Inc. 
3201 Calle Marie 
Santa Fe NM 87507 
505 424-1112 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Dickson

Hello Wrenches, 

I have a customer that has really likes the thought of being off-grid and
they have asked me to design a system for their “lodge”.  I have kicked and
screamed to get them to consider a grid-tied system using their existing
grid service—to no avail.  

After doing a preliminary load analysis, I have determined that it would
take ~35kW of solar and a couple Bergey Excels for it to work along with a
19,000Ah battery bank.  

So, how big is too big?  If we were to move forward on this, what would be
the major obstacles/show stoppers besides the price (as price is not an
issue)?

What are some of the largest battery based systems that you have installed
or heard of?

Any input is welcome. . .besides being told just to run away from this one.
. .

REgards, 

Mark Dickson

Oasis Montana Inc.

HYPERLINK "http://www.oasismontana.com/" \nHYPERLINK
"http://www.oasismontana.com/" \nwww.oasismontana.com

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