# question

asked

## Large BESS with 15 Quattros - can we split into 5 AC-coupled independent BESS?

Designing a 3-phase BESS with 15 Victron Quattros (left side of diagram).

To make the current handling more manageable, and to add redundancy, we'd like to split the system into five BESSs (right side of diagram). If so required, a single BESS can go off line and later come back on line.

Is this possible? Either with 5 independent BESS (where one operates as off grid and the other four as grid interactive) or with one Quattro being the leader and the other 14 being followers.

large-bess.png (188.0 KiB)

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
Paul B answered ·

What you are asking cant be done,

first off all all the inverters have to run off one LARGE battery BANK.

second each phase is programmed to have 5 units in parallel and then each phase HAS to have 5 units in each phase all the time. totaling 15 units.

third if you could connect all 5 units per phase then thats a 75,000 VA per phase and that means at max overload ( being 100% though not for long))at 52 volts the amp draw per phase could reach 1442 amps so with 3 phase all running amps drawn from the bank could be as high 4300 amps if all phases are loaded at the same time , very big fuses and bus bars and batteries required.

also I do not think that its advisable to go over 3 quattro 15000 in parallel, in these larger units so max size would be 9 x 15000 units (3 in each Phase)

I would suggest that you have more discussions with a authorized Victron Distributor in your area.

Also are the PV panels going to be DC connected IE direct to the batteries or AC connected being connected to ac1 out.

2 comments

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

·
Thank you for your advice, which I am taking to heart, and for sharing your expertise.
0 Likes 0 ·
·

> Also are the PV panels going to be DC connected IE direct to the batteries or AC connected being connected to ac1 out

This is a DC-coupled solar system.

0 Likes 0 ·

### Related Resources

Victron Offgrid page

AC-coupling and the Factor 1.0 rule

AC-coupled PV with Fronius PV Inverters

Additional resources still need to be added for this topic