can my system accept a second battery pack?

[BAndrews]

A relative bought a package from a very decent company a few years back.  I've been press-ganged into setting the system up   :-).  Some of the goodies:

(eight) Solarworld, 265W panels, Sunmodule Plus, Black/Black Mono 2.5, SW265 W (the numeral eight in parenthesis was acting oddly)
(4) Rolls Surrette 6v, 400 AH S530 S-530 WET
(1) Midnite Solar classic 150
(1) 4 Star Solar MS4024PAE Single Magnum inverter


System is wired for 24V.  Zipcode is 32440.

Is this system strong enough to power a second 24 volt battery pack wired in parallel with the original?  If the system will accommodate another battery pack, can the new battery pack be a slight mismatch on specs?  The Rolls S530 is no longer available so I was wondering about a slightly bigger Rolls or Crown 24V pack.....

Sure would appreciate any advice.

[Syonyk]

How are you planning to set the panels up?  I don't think you can do 4 in series with the Classic 150 for voc reasons.  Two in series, 4 of those strings in parallel?

You can probably wire a second pack in parallel, but it's going to be difficult to keep everything happy.  Lead acid doesn't parallel well with different cells or even different ages of a certain battery.

[BAndrews]

How are you planning to set the panels up?  I don't think you can do 4 in series with the Classic 150 for voc reasons.  Two in series, 4 of those strings in parallel?

You can probably wire a second pack in parallel, but it's going to be difficult to keep everything happy.  Lead acid doesn't parallel well with different cells or even different ages of a certain battery.

Hello! 

I should have provided more detail on the layout.

The system has four panels per pole mount ...... and two pole mounts.  As you surmised, each group of two panels is wired in series producing about 60 volts.  Then four of these strings in parallel.  The system was running yesterday for the first time on six panels (waiting on wiring for panels seven & eight).  It's a beautiful thing to see.  Amazing.  Flawless.

The owner really wants a second battery pack but it sounds problematic.  Is there somewhere that would accept these batteries in partial trade on a matching eight-pack?  I don't know if these types of things come up very often.

[russ_drinkwater]

You can do as I will be and have a isolator switch to change feed from reg to each battery pack for now until you get something sorted.
Four positions 1. off 2. bank one 3.bank two 4. both banks
Have a similar problem here, but I think I will run one reg to each bank as I have two 150's here and switch between banks on the feed to the inverter as needed. One bank for during the day (smaller 870 amp) and bank two for night time (2700 amps @ 24 volts).
A tad messy but wife can handle it then it is all good!