A Forum run by Enthusiasts of MidNite Solar

General Category => System Design and Layout => Topic started by: openplanet on March 15, 2017, 10:58:13 PM

Title: Worth changing from 24 to 48vdc battery bank?
Post by: openplanet 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!
Title: Re: Worth changing from 24 to 48vdc battery bank?
Post by: ClassicCrazy 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
Title: Re: Worth changing from 24 to 48vdc battery bank?
Post by: CDN-VT 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
Title: Re: Worth changing from 24 to 48vdc battery bank?
Post by: mike90045 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"
Title: Re: Worth changing from 24 to 48vdc battery bank?
Post by: openplanet on March 16, 2017, 10:53:48 AM
CDN-VT...Your post is rather cryptic. Could you expand / clarify? Thanks!
Title: Re: Worth changing from 24 to 48vdc battery bank?
Post by: TomW on March 16, 2017, 12:37:45 PM
Quote from: mike90045 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"

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
Title: Re: Worth changing from 24 to 48vdc battery bank?
Post by: openplanet 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.