[RE-wrenches] 24 vs. 48

[Jay Peltz]

Hi Mark

I think it's other things that help to determine it
Array size and therefore # of CC
Battery size and # of parallel banks
Inverters and cabling

This system at 24v requires 2 CC, 4 parallel strings and dual 4/0 cables  vs a 48v would be single CC, 2 strings batteries and a single 4/0.

In the it's just cheaper in this  case and better in terms of battery design

My thoughts
Jay

Sent from my iPhone

On Jan 17, 2012, at 11:19 AM, "Mark Frye" <markf at berkeleysolar.com> wrote:

> Interesting.
> 
> I can choose an OB VFX3524 w/ 85 ADC or an OB VFX3648 w/ 45 ADC of charging
> capacity.
> 
> And assuming that I need C/10 during bulk charging (and the importance of
> this is really what I am asking about) then:
> 
> VFX3524: 85 ADC * 10 = 850 AH * 24 VDC = 20.4 kWH battery bank
> 
> VFX3648: 45 ADC * 10 = 450 AH * 48 VDC = 21.6 kWH battery bank
> 
> OK, so it's about a wash either way in terms of stored energy.
> 
> But assuming for the moment that distances are short and the initial
> difference in copper costs are small, wouldn't you rather have half the
> number of individual cells to maintain...less watering, less SG measuring,
> lower overall "part" (individual 2V cells) count?
> 
> Mark Frye
> Berkeley Solar Electric Systems
> 303 Redbud Way
> Nevada City,  CA 95959
> (530) 401-8024
> www.berkeleysolar.com 
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray
> Walters
> Sent: Tuesday, January 17, 2012 10:38 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] 24 vs. 48
> 
> The only advantages of 24 v are that you can create smaller KWH battery
> banks, and that Bergey's XL.1 was only available in 24 v.
> Anytime the design allows, I jump to 48 v.
> 
> R. Walters
> ray at solarray.com
> Solar Engineer
> 
> 
> 
> 
> On Jan 17, 2012, at 11:11 AM, Nathan Jones wrote:
> 
>> 
>> 
>> Mark,
>> It would seem to be a wash. As the voltage is halved the amperage is
> doubled in the battery bank. This would seem to require doubling the
> charging amperage so nothing is gained. On a system of any size the 48 volt
> gets the default nod here. Charge controllers handle twice the solar.
> Parallel battery strings are eliminated, or at least held to two. Wire
> sizing might be reduced on the low voltage side of things. And much easier
> future expansion possibilities, too.
>> Cheers,
>> Nathan Jones
>> Power Source Solar Inc
>> 
>> 
>> ------------------------------
>> On Tue, Jan 17, 2012 10:56 AM CST Mark Frye wrote:
>> 
>>> Not really on topic to Jay's question, but...
>>> 
>>> Is 48v always better than 24v?
>>> 
>>> How important is bulk charging current to overall battery life?
>>> 
>>> In some cases, isn't it better to use a 24v inverter/charger which 
>>> can develop a higher charge current for a battery bank that has a 
>>> higher AH rating?
>>> 
>>> Mark Frye
>>> Berkeley Solar Electric Systems
>>> 303 Redbud Way
>>> Nevada City,  CA 95959
>>> (530) 401-8024
>>> www.berkeleysolar.com
>>> 
>>> -----Original Message-----
>>> From: re-wrenches-bounces at lists.re-wrenches.org
>>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of jay 
>>> peltz
>>> Sent: Tuesday, January 17, 2012 8:43 AM
>>> To: RE-wrenches
>>> Subject: [RE-wrenches] battery buss bars
>>> 
>>> Hi All,
>>> 
>>> Where do I find buss bars for a battery parallel problem?
>>> 
>>> I've got to fix a brand new ( not me) system, that has 4 sets of 
>>> L-16's at 24v.
>>> Yea yea why didn't they go to 48?
>>> 
>>> So I want to use buss bars to parallel them, and looking for premade
> ones.
>>> 
>>> Thanks in advance,
>>> 
>>> Jay
>>> 
>>> Peltz power
>>> 
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