ESS with only 2 Victron Multiplus II in a 3 x 230V delta grid

Q&A and troubleshooting
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1

We live in Belgium and have a 3 x 230V delta grid connection. We have solar panels and have been looking for a way to store this solar energy in a battery so that we can use it in the evening. Also as a backup when the grid goes down, which happens quite regularly in our region.
At the moment, we have 2 inverters from Solaredge SE3500. SE1 is connected to phase A, and SE2 to phase B. Phase C only receives energy from the grid. And this combination works excellently.

We would of course like a full-fledged 3-phase system, but that does not exist for our grid. The ESS system with the Victron Multiplus comes closest to our wishes because the Victron Multiplus II can work together with the Solaredge inverters.

I have created a schematic diagram, and now my question is: can this work?

Schema 2MP for 3 x 230V delta
Schema 2MP for 3 x 230V delta1082×746 121 KB

It is not the intention to have a complete 3-phase 230V delta, as I have already found that this would not be possible. But rather something that might work?

First, a bit of explanation about the diagram. FM1 is a phase monitor (like the Schneider RM22TR31). As long as all phases are at their normal voltage, the relay output of FM1 is ON, and thus the contacts of the relays CR1 and CR2 are closed. The Multiplus units can operate normally, charging the battery with solar power during sunny hours, etc., as described in the Victron documents.

If the grid goes down (or if one phase goes down), FM1 detects this and opens CR1 and CR2. Phases A and B receive energy from the battery via MP1 and MP2. Phase C does not receive voltage because CR2 is open. This is necessary to prevent ghost voltage on L1 and L3.

When the grid is restored, CR1 and CR2 turn back ON, but after a time delay. This time delay (ON Delay) is adjustable in FM1. I would set this to 20 seconds. When the grid comes back ON, it often happens that it goes down again within a few seconds. ON – OFF – ON – OFF… is not very healthy. Therefore, I would prefer to wait 20 seconds for a stable grid.

I would disable the Ground Relays in both Multiplus units.

What do you think about this? I hope there are specialists here who can help me ?
Thank you very much for this.

2

I made a mistake in the diagram; the outputs of the Multiplus II should not be connected to the grid. The diagram has been adjusted, but the question remains: Could this work?

Victron ESS-3
Victron ESS-31082×746 129 KB

4

Yes, the Ground Relay must be disabled. I suspect that this could work, but before I order anything, I want to be sure. Should the settings be on 3 phases? Because it is not really 3 phases; it’s just that MP2 is 120° shifted compared to MP1.

5

https://www.victronenergy.com/live/ve.bus:manual_parallel_and_three_phase_systems

Delta configurations not supported

For units in 3 phase configuration: Our products have been designed for a star (Y) type three phase configuration. In a star configuration all neutrals are connected, a so called: “distributed neutral”. We do not support a delta (Δ) configuration. A delta configuration does not have a distributed neutral and will lead to certain inverter features not operating as expected.

6

Yes, but it is not a complete 3-phase system. My solar inverters also cannot operate in a 3-phase delta configuration; inverter 1 is connected to L1 - L2, and inverter 2 is connected to L2 - L3. And that works well.

If I follow the same philosophy, would this not also work for the Victrons? The Ground Relay must be disabled, and MP2 is 120° shifted compared to MP1. There are no 3-phase connections at the consumers (no motors, etc.).

7

Regarding the technical questions, I don’t know if this will work. I would however like to know, because I’ve already thought about this possibility.

But regarding the regulatory side: I’m not 100% sure, but I think in Belgium everything that CAN have solar panels attached does not count as battery inverter but as PV inverter. If this is the case total PV inverter apparent power would be the sum of the SolarEdge and Multiplus. With already 7kVA from AC inverters this could be above 10kVA. So this topic may be worth investigating before.

8

This is what I found:
For the inverter(s), there is a limitation of 5kW (single-phase) or 10kW (three-phase) that only applies to PV inverters and hybrid inverters.

Battery inverters (retrofit) do not count in the calculation as PV.

However, in installations with a separate battery inverter, a (approved) power management system is always required (Synergid C10/11 §7.11.2).

This “EnFluRi” must be set up so that no more can be injected than the capacity of the PV installation.

The Multiplus units can be considered as retrofit battery inverters. The intention is to use the energy directly as much as possible during sunlight hours, with any surplus going into the battery. In the evening, I will primarily draw energy from the battery.

9

If delta is an unsupported Victron configuration, will you succeed with the required AREI/RGIE inspection? I’m not sure the EnFLURI sensor can be installed with this setup?

If you disable the ground relay, is RCD protection on AC-out still working?

10

It’s counted differently here:

4.1.10 hybride omvormers
“Bij de bepaling of een installatie kan beschouwd worden als een “kleine productieinstallatie” volgens de definitie van §4.1.7 wordt het vermogen van een dergelijke omvormer niet meegeteld als energie-opslag-systeem, maar wel bij “Som van de vermogens van de elektriciteitsproductie-eenheden, anders dan de eventuele energieopslagsystemen”. Dit geldt ook in het geval er aan de DC-zijde van een dergelijke eenheid (nog) geen productie anders dan batterij-opslag is aangesloten.”

I think this means that Multiplus II are always counted as PV inverter and not as battery inverter.

11

@skibbi
Bedankt voor het document van Synergrid.

Voor details over reglementering in België kunnen we beter verder gaan in het Nederlands.

For details about regulations in Belgium, it would be better to continue in Dutch.

Volgens 4.1.7 in het document is een kleine productie-installatie als volgt:

Bij aansluiting op een 3 fasen net mag de “Som van de vermogens van de elektriciteitsproductie-eenheden, anders dan de eventuele energieopslagsystemen niet groter zijn dan 10kVA”
Som van de vermogens van de energieopslagsystemen (omvormer(s) v.h. batterijsysteem) niet groter zijn dan 10kVA.
Volgens de tabel mag bij 3-fasen het totaal van de PV omvormers max. 10 kVA zijn, en het totaal van de batterijomvormers mag niet groter zijn dan 10kVA. In dit geval mag er maximum 10 kVA naar het net geïnjecteerd worden. Dit moet ingesteld worden in het EnFluRi systeem (sensor).

Maar; als de regeling van de energiestromen aan de DC-zijde gebeurt (dus bij een hybride omvormer), en het totaal geïnjecteerde vermogen nooit groter kan zijn dan het maximaal AC-vermogen van de omvormer zelf, is voor dergelijke systemen geen EnFluRi sensor verplicht. Een goedgekeurde EnFluRi voor Victron is de CT van de Multiplus zelf.

Per Multiplus II 48/5000/70/50 is de maximale AC uitgang 5000VA, voor zo’n 2 omvormers is het dus 10 kVA. Dus binnen de norm van een kleine productie installatie.
Voor mijn 2 PV omvormer (2 x 3500 VA) heb ik dus 7 kVA. Dus nog altijd binnen de norm van een kleine installatie.

Maar in dat document staan er toch een aantal tegenstrijdigheden.
De vraag blijft is het mogelijk volgens mijn schema? Kan dit werken ?

12

I have meanwhile submitted a request to my distribution network operator to switch to 3N400V. From an initial message, it seems that it might be possible!?? In a few weeks, a technician will come to assess whether it is actually feasible. So I will wait and see.

13

I’m curious to see if that will work out. Then you would have to get a completely new 4 x Xmm² feed with a PEN conductor. Keep your fingers crossed …

14

The connection cable was installed in 2008 and is an EXVB 4 x 16mm². I think the cable between the meter box and the street connection is okay.

15

oh thats a 4x16 copper cable … step 1 … check :+1:

16

Also, when speaking of wire dimensions:
When you are planning to use the same wiring for the solar inverters and the Multiplus the wiring must have the correct size for both appliances to work simultaneously (they are both energy producers).
So you also have to take into account the rules for an electric house installation :slight_smile: .