2 x Multiplus ii 8Kva Not working in parallel

[Jonathan22 (Jonathan Manjoro)]

Good day

Just finished wiring 2 x Multiplus ii 8kVa inverters in parallel

External Transfer switch and External Ground relay both wired according to the manual

inverters connected perfectly in parallel

inverters have different firmware, but same Comp ID, and Victron supplier confirmed they are compatible

S99 inverter firmware used

100A Victron CT installed

Grid code used: “Other, not compliant to any grid standard”

NO Ziehl relay used

When I switch the system ON, it’s not engaging. The Master inverter has all 3 charge status LEDs flashing

Manual says it’s a configuration or CT issue, but I can’t figure out where exactly I missed it

Is there anyone who can assist me remotely on site, as this is pretty urgent

[nickdb (Nick)]

@Jonathan22

inverters have different firmware

What do you mean by this?
All systems should be on the same version.
Those 3 flashing LEDs mean Hardware or EEPROM error - in this case a config mismatch of sorts.

The community can’t offer that kind of support, it is not a support site. You will need to involve your supplier for assistance.

[Jonathan22 (Jonathan Manjoro)]

Please see attached compatibility ID form from Victron

I’m connecting 2 inverters, 3 years apart, in parallel

Old inverter Serial number: HQ2220C4VY3

Old inverter firmware: 2621563-s99

New inverter Serial number: HQ2545YNP6P

New inverter firmware: 2682563-s99

New inverter Comp ID 2621_A

Old inverter does not have a Comp ID on the sticker, meaning the first 4 digits of the firmware plus A is the Comp ID (Which is 2621_A)

According to Victron, these inverters can be paralleled (see attached reply from my dealer), so I guess that removes the inverter compatibility issue

The inverters are also syncing in parallel with no issue.

If you can please let me know if there are other settings that I skipped, or if this was not a very accurate answer

Another test done

I’ve tested the old inverter, which is the Master, as a standalone, and it engaged perfectly. I couldn’t test the new one because I didn’t have a compatible CT for it. I’ll test it on thursday and give feedback

See also attached VE Config screenshots

2026-05 - Compatibility ID explanation and handling guidelines.pdf (505.4 KB)

[nickdb (Nick)]

Have you enabled the external CT on the master, configured the rating? The secondary unit doesn’t need one, there is one per phase.
Comp ID’s are right, so something else is off.
Maybe attach your remote config file here from VRM.

If all else fails, flash them with veflash and try again.

[lxonline (LX)]

I was thinking about this. The one confog error inhave seen twice is this one

4.2. VE.Bus System configuration - 4. Configuration

Grouping them incorrectly.

Group 1 is masters for all phases

Group 2 for slaves.

[Jonathan22 (Jonathan Manjoro)]

Thank you

I programmed the parallel setup using VE Quick configure. Didn’t think it would make a difference since it’s only 2 inverters parallel in single phase.

I will use the VE System configurator when I get back to site

[lxonline (LX)]

All Victron multi inverter systems are configured with VE.Bus System Configurator. And through it all inverters are programmed through it (right click and configure) ve bus config like singe unit ve bus systems are.

[Jonathan22 (Jonathan Manjoro)]

Thank you

I reprogrammed the inverters with System VE Configurator, like what you said. Everything is working perfectly now. The 2 inverters, though having different Firmware versions, have the same Component IDs, which makes them compatible

[lxonline (LX)]

@Jonathan22

though having different Firmware versions

Ultimately they should both be updated to the same firmware.

Excellent. Glad you are up and running