question

petajoule avatar image
petajoule asked

Can GX cope with two Inverter "systems"?

For two very special projects, I would like to modify the original design which was


3 x Multiplus-II 10kVA (3-phase core) + Fronius Symo
3 x MPPT-RS 450/100 (DC branch)

to

3 x Multiplus-II 10kVA (3-phase core) + Fronius Symo
2 x MPPT-RS 450/100 (DC branch)
1 x Multi RS Solar 48/6000 (including a dual-tracker MPPT 450/100 equivalent)

Reason being, that I would like to have the 6kVA Inverter as fallback in case one of the Multiplus went kaboom. Yeah yeah - no 3-phase then etc.

Question is if I connect the MPPT-RS and the RS Solar via CAN to GX, plus the Multiplus via VE-Bus if the GX will or will not get a split brain syndrome? In the ideal case, I would like the GX to show only the 3xMultiplus-II system and consider the Inverter in the RS Solar dormant.

cerbo gxMulti RS
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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

The GX device is set up to handle only one inverter/charger system (your 3x Multiplus in this case). Any additional inverter/chargers will appear in the device list only and not be included in system totals shown on the pages showing the components as tiles.

You might be able to get the Multi RS to "take over" for the 3x Multi system in the event the latter fails. Disconnecting the VE.Bus connection to the GX device and rebooting will possibly trigger the change. You would of course need some AC switching in order to transfer AC inputs and outputs between systems.

You should be able to include the MPPTs in the Multi RS for solar charging even of the 3x Multi is active.

The Multi RS AC input would charge the batteries but probably would not be included in the AC input power calculations shown on the various pages.

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Alexandra avatar image Alexandra ♦ commented ·
@PetaJoule

For simplicity lets just say this is not intended/officially supported use for the GX. It is designed for one system.

It will be able to monitor and control one VE bus system.

Only monitor the second system.

If you can connect the multi RS it will see/use the mppt in it. With the main system.

If it is sharing the battery bank, not sure how that would be a good fail safe system. Often on bigger systems that is the cause of shut down.

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petajoule avatar image petajoule Alexandra ♦ commented ·

Thanks. I intended to connect the Multi-RS only via VE.Can as I would have done in the case of 3 MPPT-RS and connect only the Multis via VE.Bus.

"If it is sharing the battery bank, not sure how that would be a good fail safe system. Often on bigger systems that is the cause of shut down."

Let's just say that I trust the battery in that system more than a 3-phase config of 3 Multi-II. However, if someone manages to pull out the MTTF or MTBF information out of Victron for a Multi-II that would change my mind - I'm all ears.

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petajoule avatar image petajoule commented ·

Thanks a lot - all of that makes sense, but it would be a shame if the AC-Input charging would not go into the calculations as in one of the systems there is a small Honda Inverter Genset planned for it.


Well - not sure if a Skylla-TG 48/50 that was considered an alternative in that case would show up either.


edit: oh wait - of course it would show up (any charger), because there is a SmartShunt "in front" of the battery which is used for monitoring DC in/out of the battery.

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