4x inverters to 1 big battery bank or to subsets of batteries

[chrisjx]

I'm planning to connect 4x eg4 6000 inverters to 14 EG4 LifePower4 V2 batteries. Please, the pros and cons of one big battery bank vs 2x 3 batteries + 2x 4 batteries into each inverter. I'm leaning towards one big battery bank but now second guessing myself...

Also what kind of bus bar / fuse configuration is recommended? These inverters and batteries have breakers built in.

Thank you,
Chris.

 

[DIYrich]

If the inverters are in parallel, the batteries should be in parallel too. PV from one inverter may be charging the bank while another inverter is taking power.

 

[wpns]

One Big Bank will allow you to share power between all the pieces, definitely the way to go. Even if the loads are the same because all the inverters are in parallel the SCC will probably be producing different charge power over the course of the day as @DIYrich pointed out.

 

[Q-Dog]

Calculate the largest loads you could have if all inverters are drawing max capacity. Start there with calculating how big the bus bars need to be.

 

[Quattrohead]

Parallel the whole lot together, job done.

 

[DIYrich]

Calculate the largest loads you could have if all inverters are drawing max capacity. Start there with calculating how big the bus bars need to be.

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On average, no part of the busbar will see more than 125a max battery connection of an inverter. Still would use a 600a busbar since that is the max draw of 4 6000xp.

 

[wpns]

If you haven't already bought the LifePower4 batteries, the PowerPro WallMount batteries have 600A bus-bars built into them, so this becomes a lot easier.

 

[EPicTony]

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On average, no part of the busbar will see more than 125a max battery connection of an inverter. Still would use a 600a busbar since that is the max draw of 4 6000xp.

If you can setup the connections as suggested by DIYrich that would be optimum. I have 3 inverters and 14 batteries, 1 x 4/0 cable for Positive busbar. 1 x 4/0 cable for Negative busbar. Works fine with 400a busbars, I wish I had the 600A busbars setup like DIYrich mentioned. I limit the charge current to 100A so the max I get is 300A. Yes the 4/0 does get pretty hot at 300A.

 

[Garrik]

When in doubt, do what the manufacturer recommends. From the manual for the PowerPro battery:

Emphasis mine: "Common busbars are superior to separating battery packs..."

"The maximum recommended number of paralleled 18kPV inverters is 6. If this approach is
used, we recommend a ratio of 3 batteries per pack controlled by each 18kPV inverter. Separating
packs is only recommended if each pack's average SOC is monitored over time and does not diverge
by more than 10%. Common busbars are superior to separating battery packs but it may be difficult
to source fused positive busbars rated to greater than 1800 Amps. This translates into separating
packs larger than 9 batteries. "

 

[Mark D]

Only advantage i see to splitting the banks would be for preserving one bank relative to another. But this generally sounds like a less than ideal scenario under most circumstances and I would not recommend it unless you were trying to equalize cycle counts between packs or something to that effect.

 

[AdamsSolarProject]

One Big Bank will allow you to share power between all the pieces, definitely the way to go. Even if the loads are the same because all the inverters are in parallel the SCC will probably be producing different charge power over the course of the day as @DIYrich pointed out.

Agree on the one big bank!