Author Topic: Worth changing from 24 to 48vdc battery bank?  (Read 310 times)

openplanet

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Worth changing from 24 to 48vdc battery bank?
« on: March 15, 2017, 10:58:13 PM »
I currently have:

*24 volt, 405ah battery bank in the form of 4, 6 volt batteries in series
*2 series strings of 3, 295 watt panels (about 110 vdc comes in to the controller)
*Classic 200
*lights, ceiling fan, and 'fridge are 24vdc
*24v, 2kw inverter

I'm planning to add two more strings of 3 panels each and another Classic 200.  I could double my battery capacity with either

*two parallel 24v strings of 4, 6 volt batteries, or
*a single series string of 8 batteries for 48 volts.

In either case they'll all be new batteries.  I understand that (1) it's better to avoid parallel battery strings if possible, and (2) the controller is more efficient as the input voltage is closer to the battery bank voltage.  In order to convert to 48vdc I'd need to (1) sell my 24v 2kw inverter and purchase a 48 volt unit, and (2) purchase a DC-DC converter to run my 24v loads.

Here's the question: Given the above, are the benefits of going to 48vdc worth the cost?

Thanks!

ClassicCrazy

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Re: Worth changing from 24 to 48vdc battery bank?
« Reply #1 on: March 16, 2017, 12:42:35 AM »
I believe the new Midnite inverter coming onto the market in the near future will be 48v so that may be  a consideraton.  I think the controller modules may be integrated into it so that may be something to consider if you want to upgrade.  There was a youtube video on Alt E about the new Midnite inverter .

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

CDN-VT

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Re: Worth changing from 24 to 48vdc battery bank?
« Reply #2 on: March 16, 2017, 03:09:47 AM »
Here's the question: Given the above, are the benefits of going to 48vdc worth the cost?
new 48 Vdc inverter + is also needed .
48Vdc harvest is twice the 24Vdc harvest . MATH is needed

 
VT
« Last Edit: March 16, 2017, 11:41:21 PM by CDN-VT »
Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
48Vdc almost done.

mike90045

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Re: Worth changing from 24 to 48vdc battery bank?
« Reply #3 on: March 16, 2017, 10:28:56 AM »
I've never seen any posts where someone was sorry they went to a higher voltage (48V)

Lots of folks moaning:  "have to get new controller, this one is maxed out at 24V 65A"
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

openplanet

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Re: Worth changing from 24 to 48vdc battery bank?
« Reply #4 on: March 16, 2017, 10:53:48 AM »
CDN-VT...Your post is rather cryptic. Could you expand / clarify? Thanks!

TomW

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Re: Worth changing from 24 to 48vdc battery bank?
« Reply #5 on: March 16, 2017, 12:37:45 PM »
I've never seen any posts where someone was sorry they went to a higher voltage (48V)

Lots of folks moaning:  "have to get new controller, this one is maxed out at 24V 65A"

Mike;

I never heard anyone whine about going up in battery volts beyond the equipment upgrades needed, either. Of course, The Classics are capable of a range of battery voltages so that is good to go for 48 volts in this case.

Yep, The Classics are rated in current and any time you have the same amps at higher volts you obviously have more power. But you know that, I am sure.

The point may be less than obvious to some of folks.

Just from here.

Tom
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

openplanet

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Re: Worth changing from 24 to 48vdc battery bank?
« Reply #6 on: March 17, 2017, 02:15:40 PM »
One other consideration that some have brought up but that I forgot to mention is that it's worth having 2 parallel strings so that if a battery fails you can limp along on one string until battery is replaced.  Personally I don't find this a compelling reason to stay with 24 volts, but I'm curious what other think.  Thx.