Hello, yes, indeed, I’m in Belgium and the regulations aren’t the same as in France. I do wonder, in fact, whether it might be safer to do things the French way… Do you have an opinion on that?
The panel configuration dictated my choice; I’m starting with an existing installation (SMA without a battery) that I’m modifying. The 250/100 will be connected to 3 strings of 5 panels; the voltage would be too high even for a 450/100, so I chose to put 3*5 PV panels in series. The RS450/100 is the only Victron MPPT that can accept my 8 existing PV panels in series, and I’m adding 10 PV panels in series that I removed from my roof. That’s why I didn’t choose the RS450/200 Thanks for your reply!
pourquoi compliqué?
soit il fonctionnent ensemble et synchro dans ce cas il y a un maitre et un esclave , cela ne pose pas de soucis, soit, il fonctionne de façon independante et dans ce cas un est relier en vebus l’autre avec mk3 et la aussi pas de soucis du moment qu’il n’y ai aucun lien entre les entrées et la sortie.
Salut @thierry_cortassa , dans son explication initiale Miguel ne parlait pas de mise en // et aussi je n’ai pas lu qu’il se trouvait en Belgique, @Q.x semble au courant.
Hello everyone, I would like to show you the overall AC wiring diagram for the installation to check that there aren’t any errors in the way it has been designed. It is certainly not complete; that will come at a later stage.
It’s only a draft, mind you! When I see your superb drawings, I feel a bit embarrassed LOL. This represents a new main enclosure. I have a single-phase 230V supply WITHOUT a neutral (Belgium)
New Hager CFA240E RCD, supposedly more resistant to interference
EM540 meter (will it work with two phases?) Configured as a grid meter in the Multiplus, it will allow the heat pump and EV charger to be powered when there is surplus PV generation
Parallel supply to a future heat pump, an installed EV charger, the Multiplus 48/5000 and the grid side of the Hager changeover switch
On the AC/OUT, a 40A circuit breaker and 300mA RCD before connecting to the backed-up side of the changeover switch. I am keeping it at 40A because the largest loads are upstream of the Multiplus; I don’t see any need to increase it to 50A. What do you think? I have installed a 300mA RCD on the AC out to protect the downstream installation in the event of a grid failure.
The changeover switch supplies my existing consumer unit, from which I will have removed the 300mA RCD. The dedicated 30mA RCD remains in place.
Can you see any errors? Any improvements?
Thanks in advance.
There should be a circuit breaker downstream of the power sources (Grid + AC IN), before supplying the loads (heat pump + EV + source inverter).
Basically, especially if the source transfer switch is switched to the grid, the MultiPlus-II will compensate for the load up to its limit, generating a current of around 21 A, to which the 40 A from the grid could be added. This means that more than 60 A could flow through part of the installation. I don’t know whether the RGIE permits this situation. In France, for the past year, Consuel has been paying attention to the risk arising from the combined current of the sources exceeding the installation’s rated current.
In any case, a circuit breaker is enough to protect against this risk. So don’t hesitate to add one.
Regarding the EM540 meter, I have the impression that it should work if one phase is considered to be the neutral. But I still have my doubts about that.
Why don’t you install a single-phase meter, either an ET112 (out of stock) or a B21?
Thanks a lot for your reply. I’m not sure I understand where you would add a circuit breaker; there is already a 40A one downstream of the meter, and then ones on the AC-IN, the heat pump and the EV. Would you put it between the EM540 and the others, at the red point?
Regarding the EM540, it’s the only one available from the Victron supplier I’m going to buy from (not too expensive at €101.67). He told me it would work with this wiring, with L2 instead of the neutral:
I’ve looked into the ET112 and the EM24, but they’re not exactly easy to find. Unless you have a source, I’ll stick with this one and hope the supplier knows what he’s talking about! They’re Victron importers, so it would already be surprising if they got it wrong.
Regarding the combined loads, I don’t really understand what you mean. The transfer switch is only used to bypass the system in the event of a fault or modification. If I’m on the grid side, nothing is powered by the MultiPlus anymore, so there’s no risk of the loads being combined.
When the transfer switch is on the AC OUT side, the battery power can indeed be added to the grid power, allowing up to 45A on the AC OUT (that’s what I read), but I don’t think it will be necessary to go up to 50A, since the largest loads don’t pass through the MultiPlus.
Does that sound right to you? Or is there something I haven’t understood? This is still something to confirm; I could also install a 50A circuit breaker downstream and a 63A RCD. In principle, the RGIE should err on the side of safety and support this approach, shouldn’t it?
In your posts, I can see that you have experience with Belgian 3*230V systems without a neutral, and the question of whether the earthing relay should be enabled or not has been bothering me… The Victron supplier told me that it was fine with single-phase 230V without a neutral and that islanding would work without any problem, with the relay that grounds L2 closing. However, I’m surprised to see so many posts about these issues if it’s really that easy! I take it that the problem mainly occurs with 3*230V systems?
Do you have an opinion on the matter?
Once ESS is configured, the GX instructs the MultiPlus-II to balance the point where the grid meter is located. Whether the consumption is on the AC IN or AC OUT side makes no difference, because when the grid is present, AC IN is physically connected to AC OUT. So the energy goes where it’s needed. Besides, you’ll be happy to run your heat pump and EV charger using your solar energy. So, the energy leaves the MultiPlus-II through AC IN to power the loads connected there. This energy can be combined with energy from the grid.
Ultimately, simply switching the transfer switch is enough to end up in this situation. If the installation isn’t monitored, this will go unnoticed until the next grid outage.
In practice, the risk seems low, but these are safety principles that must be applied. There have been many such errors in the past. Fortunately, things are evolving.
To remedy this, you can install a 40 A or 63 A circuit breaker, provided that the installation can support it (16 mm² instead of 10 mm², a 63 A residual-current device in the existing consumer unit if necessary, etc.)
I think the single-phase EM540 on L1–L2 supplied by a 3×230 V grid without a neutral, with phase L1 or L2 serving as a virtual neutral, should work. However, this meter is certainly not suitable for a three-phase 3×230 V installation without a neutral. There are several threads discussing this. Conceptually, it’s unfortunate to install a three-phase meter while using only one of the three phases, but, as you say, single-phase meters are impossible to find at the moment.
As for the earth relay, islanding should not cause any problems.
It’s really hard to find the ET112…
I asked Thierry in March 2026 whether Victron was planning to work on the possibility of using the VM-3P in multiphase mode. He replied: “At the moment, the VM can’t be used for dual metering. This is something the engineers would need to develop, but I can’t give you a release date or even confirm that it will be possible in the future” (and of course with an exclamation mark at the end of his sentence ;))
In any case, it would be a major advantage to use the VM if we had the ability to use the current transformers as we wanted.
Kind regards,
Patrick.
Stef_POLLAK
(sites-autonomes.fr & Team Victron Formation)
15
@patrick, it seems to me that at Intersolar, Victron announced the release of the VM-3P5A, compatible with 5A current transformers that are readily available on the market.
But the product isn’t yet available in the third-quarter price list…
Okay! I see what you mean, that makes sense! And as you say, I was counting on it to supply the EV and heat pump! I added a 50A breaker so I could stick with 10 mm². The charging point will be limited to 16A and the heat pump will be configured not to switch on its heating elements (so 16A maximum), leaving 18A for the rest of the house. The distance between the new consumer unit and the old one is 1 to 2 m, so 10 mm² will be fine.
Here’s what I’ve changed as well:
On AC OUT, I’ve fitted a 50A circuit breaker and a 63A RCD, just to provide some headroom in case lots of appliances start up at the same time. I hadn’t mentioned it, but in the existing consumer unit I’m removing the current main RCD; it will be replaced by the one for the grid supply and the one for AC OUT. Since the incoming supply to the consumer unit is being increased to 50A, I also need to replace the 40A 30mA RCD with a 63A one.
I think the AC side is all right? Is that correct?
Regarding islanding, your reply combined with Ataum’s has reassured me!! I was pretty worried yesterday after seeing all those posts talking about problems with this neutral-less current. I’m ready to buy all the equipment, but I need to be sure about everything first!
Thanks for your insightful and illuminating answers LOL
I may have to come back to you (and all the other forum members!) again about the DC side, but I have a few fewer doubts about that—well, for now
Er, just a reminder: there should be no RCD upstream or directly downstream of your M+. Protection against electric shock is provided by your main LV switchboard.
Why a 50 A and then a 63 A downstream? I don’t understand the purpose of the 63 A.
You should add a changeover switch for your EV; this would allow you to choose between grid mode and M+. Very useful for maximising your self-consumption — in summer, obviously.
Be careful with a heat pump: the manual often specifies a Type D curve.
Be careful with the maximum permissible current; 10 mm² does not automatically mean 50 A. It depends on the manufacturer’s specifications, as well as the installation method, grouping, cable lengths and temperatures. See UTC-15-105.
Otherwise, I don’t see anything else concerning your AC side.
Have you looked at the ET340? Even though it has three-phase metering, it works really well on a single phase. You can also use its second phase to calculate another input…
First of all, thank you for taking the time to reply to me
As far as I know, you can’t have two 300 mA RCDs in series, so if I put one in the backed-up consumer unit and the changeover switch is on the grid side, that would be the case. If I don’t install one on the AC OUT, does that mean that when the changeover switch is on the MultiPlus’s AC OUT side, there is no 300 mA RCD protecting the installation? Unless the main RCD upstream of the MultiPlus protects everything? What is the risk of installing an RCD after the M+?
I installed a 63 A RCD because a 40 A one isn’t suitable downstream of a 50 A circuit breaker. I don’t really see how else I could do it.
As for the 10 mm² cable, there will only be 1 to 2 m maximum between the new consumer unit and the old one, and I had found online that this was sufficient. But if 16 mm² would be better, that’s no problem!
Regarding the changeover switch for the EV, using the EM540 as the M+'s grid meter allows me to push the excess solar current upstream of the M+. How would it be better with the changeover switch?
The heat pump is for the future; I’ll correct my diagram with a Type D curve, thanks.
Thanks for your reply!
