Bob,
I totally understand the concern about multiple strings *if the strings are
connected across the battery bank* as had always been the tradition in off-grid
installations. My own experience with such a bank in my system showed why
when I had a single cell get to near meltdown. I was luck
OK, I've been hearing for years now that one battery string is best and
maybe two but no more should be used.
What is the reason for this fear ???What is the experience with
multiple strings in parallel ??
If it is because of current sharing of the strings, that shouldn't be an
insurm
Oops! Guess I should have read all the posts before I reply;->
Larry Crutcher
On May 31, 2011, at 5:23 PM, Wayne Irwin wrote:
> I think the verdict is 12 - Rolls 2-YS-31 2430 AH @ 20 HR (one string) and
> one dry spare in storage is the best case scenario!
>
> Wayne Irwin, EE
> Director of En
Wayne,
Whenever possible, always design a battery bank for a single series string.
Parallel strings require more attention and increase the probability of early
failure due to unequal charging.
Larry Crutcher
Starlight Solar Power Systems
11871 S Fortuna Road, #210
Yuma, AZ 85367
la...@starligh
On 2011-05-31 20:14, Tom Elliot wrote:
Good on the buss bars Wayne. Using them removes the concerns about
multiple strings and increases redundancy and system stability. You
won’t need 4/0 between single strings and the buss bar, you can probably
easily use smaller cable, just size it for the ind
Good on the buss bars Wayne. Using them removes the concerns about multiple
strings and increases redundancy and system stability. You won’t need 4/0
between single strings and the buss bar, you can probably easily use smaller
cable, just size it for the individual string. 4/0 to the inverter
I'd vote to listen to the manufacturer. It's in their best interest to provide
a reliable solution. Good call.
On May 31, 2011, at 8:23 PM, "Wayne Irwin" wrote:
> I think the verdict is 12 - Rolls 2-YS-31 2430 AH @ 20 HR (one string) and
> one dry spare in storage is the best case scenario!
I think the verdict is 12 - Rolls 2-YS-31 2430 AH @ 20 HR (one string) and one
dry spare in storage is the best case scenario!
Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc.
State Licensed Solar Contractor
License # CVC56695
wa...@pureenergysolar.com
http://
Just another thought- If redundancy is an issue with string sizing, having a
12v inverter handy is sometimes a viable backup option with a 24v bank with 2
or more parallel strings.
Jason Szumlanski
Fafco Solar
On May 31, 2011, at 7:55 PM, "Jason Szumlanski" wrote:
> If the choice is one or t
Tom,
Yes, but if you use individual 2V cells, you can pull one failed
cell out of the string and get by just fine by adjusting setpoints
down by 8% (11/12ths). You'll lose 8% of capacity until a cell is
replaced; or, if the failed cell is the first to go at end-of-life,
Hi Wayne,
Why not 12 cells (24VDC) and put the 13th in storage as DRY?
Regards,
Jamie
>>> Wayne Irwin 5/31/2011 9:01 PM >>>
A) With a 13th battery and only one string, if there were a failure in
one of the cells, the system would most likely demonstrate the failure
rather quickly and allo
No DC loads at all.
Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc.
State Licensed Solar Contractor
License # CVC56695
wa...@pureenergysolar.com
http://pureenergysolar.com
352 377-6527 Office
352 336-3299
Fax
352 316-1637 Cell
The
content of this message
A) With a 13th battery and only one string, if there were a failure in one of
the cells, the system would most likely demonstrate the failure rather quickly
and allow for the faulty battery to be removed while still maintaining adequate
voltage to operate the 24V system.
B) On the other han
Wayne,
I'd recommend against that. To do an effective equalization charge on that bank
you'll need to get the voltage up to at least 2.6-2.7V per cell. That would
mean a 13 cell pack voltage of 34-35V. Got any DC loads at all? Danger, Will
Robinson, Danger! Using the inverter as a charging sour
If the choice is one or three, I choose one. If the choice is one or two, I
choose two for the same redundancy benefit echoed by others. However, it
sometimes depends how remote the system is.
If you are a few miles down the road from a stocking battery distributor, one
string is great. If you
Just for a little extra.
Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc.
State Licensed Solar Contractor
License # CVC56695
wa...@pureenergysolar.com
http://pureenergysolar.com
352 377-6527 Office
352 336-3299
Fax
352 316-1637 Cell
The
content of this mess
Hello all.
I am indeed thinking of 13 - 2 volt batteries to make up a 26 volt battery bank
for the 24 volt system.
Thoughts for or against are welcome.
Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc.
State Licensed Solar Contractor
License # CVC56695
wa...@pu
>From a reliability standpoint I would never want to bet the farm on one
>string. All it takes is the failure of one cell and the system is useless
>until it is replaced. Three strings means a cell failure only reduces
>capacity by 33% not 100%. I’ve always thought in off-grid systems it is a
Fewer number of strings the better. Go with plan A. Why 13 (and not 12) of
the Rolls if I may ask?
Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parr...@calsolareng.com
Ph 323-258-8883
Wayne,
First, let's hope you mean 12 of the 2YS31. A single battery string is always
preferable to multiple strings in my book. The only downside is interconnect
cables the same size as your inverter cables. That probably means 4/0 CU for
most 24V, 3KW and up inverters. Two strings in parallel-n
My one string of 1476 AH IBE 2 V cells went 19 years before retiring them to
a neighbor's off grid system, where they are now working.
One string has my vote!
Sincerely,
Chris Worcester
Solar Wind Works
NABCEP Certified PV Installer
Phone: 530-582-4503
Fax: 530-582-4603
www.solarwindworks.co
first I am confused 12 each at 2 volts is 24 volts, also I always like one
string over two, I have experianced a battery fire with 4 strings in parallel.
From: Brian Mehalic
To: RE-wrenches
Sent: Tuesday, May 31, 2011 5:24 PM
Subject: Re: [RE-wrenches] 24
Hi Wayne-
While I think a lot of folks will agree that a single string is better for
the long term health of the batteries as it results in more even charging, I
still like the idea of at least two strings. That way if a single battery
fails, that string can be removed and the end-user can at leas
Hi Wayne,
I look forward to the input from the wrenches.
My recommendation, regardless of the brand, would be for one string.
Regards,
Jamie
>>> Wayne Irwin 5/31/2011 6:49 PM >>>
Hello Esteemed Battery Gurus,
Which of the following do you believe is the better 24 V battery bank?
A) 13
Hello Esteemed Battery Gurus,
Which of the following do you believe is the better 24 V battery bank?
A) 13 - Rolls 2-YS-31 2430 AH @ 20 HR (one string)
or
B) 9 - Rolls 8-CS-25P 820 AH @ 20 HR (3 strings of 3)
Thank you in advance for your input!
Wayne Irwin, EE
Director of Engineering
P
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