DIY 3 phase ESS installation in Belgium - Do's and dont's to get legalized (AREI)?

DIY
,
1

Hi,

I have been researching the Victron EES system and the mandatory AREI inspections in Belgium.

Currently, I have an Enphase 3-phase EQ7+ setup with 19 panels, 5300WP, which has been AREI inspected and approved.

This winter, I plan to install a 3-phase setup in my garage, located 26 meters (cable length) away from the house’s electrical panel. For this, I intend to install two 5x6mm² ground cables (one for the return path) and some double-shielded CAT 7 Ethernet cables for network connectivity and potentially some other equipment.

On the roof of the garage I would like to install 4 550Wp panels that feed into the battery via a victron MPPT

I would like to utilize the Victron backup feature to have most of my house on backup power.

In the house’s electrical panels, I plan to separate some non-essential loads, such as my EV charger, while connecting the rest to the second 5x6mm² cable that returns from the garage to the house.

I have a few questions I’m unsure about, particularly concerning the mandatory AREI inspection:

  1. Will the additional 50+ meter length of 6mm² cable pose any issues (voltage drop, or otherwise)?
  2. Can I legally place my Enphase system on the backup side, allowing solar power to operate in the event of a grid outage?
  3. Can I use the Multiplus II 5000kVA, or is there still a 10kVA limit? If I place the Enphase system on the backup side, will that add to the 3x Multiplus 3000 = 9000kVA, potentially exceeding the 10kVA limit?
  4. Can Yixiang DIY Lifepo4 battery boxes with EVE Lifepo4 cells and a JK-BMS be approved? Do they even check the DC side during inspections?
  5. Are there any other Belgium-specific rules and pitfalls I should consider?

Kind regards,

Michel

2
  • The 6mm² cable should be OK for 25A up to 2x 25m, but it’s near the limit
    You could go for a thicker cable and maybe a remote transfer switch
  • I don’t see legal limits to put the Enphase system on AC Out
  • The power of all inverters is counted, so PV and Multis.
    Up to 10kVA worth of inverters (on a 3 phase system with max 5kVA difference between phases) then can’t really refuse
    Above 10kVA worth of inverters, a net study needs to be done
    Up to 25kVA worth of inverters, that net study is free of charge but doesn’t imply your setup will get automatically approved
  • I see no possibility to get a DIY battery box approved
3

Thanks for your responses.

Regarding the last point, I have seen people get a DIY box like this approved by attaching the BMS serial number sticker to the box and providing the CE certificates for the batteries and the BMS.

I really don’t want these Pylontech batteries stacked in a tower. What are my alternatives?

Are there any more important things I should consider?
Are there schematic drawings available from people who got their setup AREI approved?

4

If you’re lucky you can get away with that but in my book it wouldn’t get approved.
The BMS and the cells might have a serial and CE certificate (that doesn’t have much value but that’s another story), but the total assembly does not.
You as the assembler have final responsibility and you can’t guarantee that the complete assembly is conform all regulations.

Are you talking about the 19" Pylontech stacks ?
They have the vertical tower stacks as well (just like BYD) and those are OK for me.
The 19" stacks have the advantage that you can connect each module independently to the busbar.

As for myself, I’m very satisfied with the BYD Battery-box Premium LVL batteries.

5

Hi Bart, I’m a bit confused. I have a 10kva 3fase SMA inverter, solar only. I would like to add a Multiplus 2 5kva as battery inverter only. I’ve read somewhere else this is allowed, but now I’m a bit confused by your reply. :slight_smile: This other info says it is allowed, if there is an approved power meter that is used by the ESS, and the ESS is set to limit total grid return to 10 kw.

As for the breaker: in the manual it says 50A, or less. I have a 40A 3F grid connection. What would be the recommeded breaker size in my situation? Last question: is it best to connect to a breaker on the 30mA or 300 mA bar?

6

Quite the confusing situation in belgium, in short;

All inverters connected to the grid must be approved and on the C10/26 list.

The multiplus 2 is on there twice, once with and once without additional MPPT solar chargers. With MPPT they are regarded as hybrid inverters.

In normal residential you ar allowed to install up to 5kVA on single phase or 25kVA on three phase of solar/hybrid inverters. You can install up to 5kVA on single phase or 25kVA on three phase AC battery inverters next to the solar inverters.

Some caveats;

In all situations there is a maximum phase imbalance of 5kVA.

If you install a hybrid inverter this counts as both a PV and battery inverter.

These regulations are from fluvius, check to see if they apply to you.

Power providers (for example engie, mega, …) can have separate contracts for people with more than 10kVA of PV.

With an installation >10kVA PV you need to have a VAT number.

Some examples;

single phase multiplus 5000 and SMA sunny boy 5000 = no problem

single phase multiplus 5000 and 5x MPPT 250/100 = no problem (only the AC inverter is limited)

single phase multiplus 3000 with MPPT 150/35 and a SMA sunny boy 3kVA = not allowed, more than 5kVA AC inverter power

three phase 3x multiplus 3000 and SMA sunny boy 10000 3ph = no problem, but the PV inverter can’t be on the AC out

three phase 2x multiplus 5000 and SMA sunny boy 10000 3ph = no problem, the PV inverter on the AC out can’t work if the grid is lost because it only gets 2 of three phases

In your case adding a multiplus will be no problem as long as there are no MPPT’s added. You won’t be able to use the SMA when there is no grid power.

In belgium the breaker depends on the wire size used, for example a 40A breaker for 3G10 or a 32A breaker for 3G6. Best installed on the 300mA bar.

7

Small correction on this:
Fluvius counts the sum of all AC inverters, so battery inverters + PV inverters and that sum is what counts as the limit.

So you can NOT install 5kVA PV and 5kVA Multi in a single phase system, the TOTAL LIMIT there is 5kVA.
If you already have a 5kVA PV inverter there, you can 't add any other inverter.

In a three phase setup, the total limit is 25kVA for the total amount of AC inverters: Multis + PV.
You can go higher but then you have to pay for a grid study.
And starting from 30kVA of AC inverters the install is considered an industrial installation and a grid disconnection board is required.

The requirement for a VAT number if you go over 10kVA AC inverters can be argued.
If you can make a very good case that you’re installing so much PV to maximize your self-consumption and not with the intention (primary goal) to sell energy (to the grid), the VAT requirement can sometimes be dropped.

8

Synergrid separates these in their definition of a small production system, see 4.1.7 kleine productie installatie. I can’t find fluvius documentation confirming or denying this.

9

I am also planning on a three phase Victron installation (in Belgium).

  • 3x MP II 48/8000/110
  • SMA 3-phase 6kW inverter, that will be connected on the AC-out

So, that’s a total of 30kVA and therefore a grid study was necessary, but it was free (because we are not changing our connection to the grid and our connection <= 56 kVA). Grid study tariffs 2025 Fluvius

It doesn’t matter that our solar inverter will be connected to the AC-out of the MPes, it counts for the total kVA. On the other side, if we were to add inverters on the DC-side of things this will not be added to the total sum of kVA.

Above 30kVA a grid disconnection protection is also required.

10

Look at Technische voorschriften elektriciteit - Synergrid at the tabel entry behind C10/11. There is also an Excel file Samenvatting van de benodigde uitrustingen in which you can see what is allowed and what not and the conditions that apply.

In a monophase connection, you may have 5kVA of solar inverters and 5kVA of battery inverters combined. In a three phase connection, an imbalance of 5kVA between the phases is the maximum imbalance allowed.

1 Like
11

In the Fluvius URL you pasted they state “inverter power: up to 5kVA on single phase or 25kVA on three phase” and this accounts for the combined power of all AC inverters - both PV and battery.
I’ve called them to double check on this.

12

With 10kVA of the SMA inverter and an additional 5kVA of a single Multi, you’ll end up with a total of 15kVA worth of AC inverters.
That’s allowed and these days Fluvius doesn’t mention the (free) grid study anymore if you go over 10kVA but not over 25kVA.
You might end up paying taxes on the injected PV power because the total inverter power is over 10kVA, unless you can argument that you do this to improve your self consumption and not with the goal of earning money by injecting solar power.

An approved grid meter is always needed for ESS, double so if you still have “green power energy certificates”.
Limiting ESS grid return to 10kW (with software settings) does not count, the combined power of all installed AC inverters (PV and battery) is what counts.

As for the breaker: that depends on what you intend to do.
A 5kVA Multi can supply ~20A of power as an inverter, but up to 50A can pass through the Multi.
If you’re never going to put more than 5kW of load on the Multi, I’d use a 20 or 25A breaker.
Otherwise you can go up to 40A, equal your grid breaker.

As for 300mA or 30mA: that depends on your use case.
If you’re going to use the Multi only as a grid buffer (so nothing on AC Out), the 300mA bus should be fine.
If you’re going to connect devices on the AC Out, you’ll need an RCD between the AC Out and these devices, as these devices will not be protected by the RCD on AC In if you’re running on battery.
And then AREI regulations state that any not-permanently connected device (read: everything connected to a power socket) should be protected by a 30mA RCD.

13

It seems, based on the post of herriejr, that you are incorrect regarding the solar inverter + battery inverter. I’ve asked Fluvius to be sure, but this seems clear:

image
image676×414 38.6 KB

14

image
image484×704 36.7 KB

15

My info dates from 1-2 years ago when I asked Fluvius specifically what the going regulations are for connecting both PV and battery inverters to the grid.

Their answer, literally translated:
“The total power of all AC inverters is what counts to determine the power level of your installation, battery or PV.
Software limiting the installation’s maximum injection power does not count (because you could cheat and change the settings afterwards).
Up to 10kVA is always allowed.
For installations >10kVA, a grid study needs to be done but up to and including 25kVA that grid study is free of charge - but it doesn’t guarantee it’ll be allowed.
Over 25kVA the grid study is to be payed and installations above 30kVA need a grid disconnection board.”

In the meanwhile it seems they’re no longer mentioning the grid study for installations ≤25kVA and never was the EnFluRi meter mentioned in the reply they gave me.

The Synergrid info you provided specifically mentions that these are the requirements to be recognized as a small production unit (as in: no TVA needed).

The matrix in the Excel file states:

  • Smax,p ≤ 10kVA* and Smax,b ≤ 10kVA* : no grid study but EnFlurRi (injection) limit is Smax,p
    (* : 5kVA for a single phase connection)
  • (Smax,p + Smax,b) ≤ 30kVA : grid study required and this determines the EnFlurRi (injection) limit, grid disconnection board required if no automatic separation
  • (Smax,p + Smax,b) > 30kVA : same as above but grid disconnection board always required.

So if both the PV and battery inverters stay ≤ 10kVA, it’s a “small production unit” but you can never inject more than the PV inverter power.
In a three phase setup you’d need 3kVA Multis to comply.
With 3x 5kVA Multis, you’re out of that rule already (damnit).

My question to Fluvius was what determines the (required) power specification of my grid connection.
Section 4.1.8 of the Synergrid document states that the maximum generated power of an installation is determined by the sum of the maximum AC powers of all energy producing units, including energy storage systems.
This corresponds to what Fluvius told me.

So it seems I was given incomplete/inaccurate information.
You can connect 5 or 10kVA worth of PV and Battery inverters without needing a grid study.
The moment either one goes over 5kVA you need a three phase grid (with max 5kVA delta between the phases) and the moment either one goes over 10kVA you need a grid study, that also determines how much you can inject.

16

Additional question regarding cable bundle and CPR (Cca) regulations:

  • regarding DC sided cables, which cables do people in BE use? Do you use regular battery cables, and put them 2 cm apart to avoid bundling? Or do you use CPR CCA compliant cables? If so, where did did you get them?
  • regarding data cables: UTP should also be CPR Cca complient when bundled, but what about the the proprietry Victron cables? Can you add them to a bundle and just say “they are part of the CE cert of the Victron”?
17

Anyone?

18

I bought RZ1-K1 Cca compliant cables at Venta Cable RZ1-K flexible Libre de Halógenos 1X50 mm2 0,6/1 KV EXZHELLENT GENERAL CABLE - Ilumitec (you can also get them at cebeo, but they charge you twice the meter cost, and 40 euro on top to cut the cable).

Concerning your second question:

  • You can’t bundle your power and data cables together, so the question is probably moot?
  • Unless I’m mistaken Cca certification is only required from 3 meters onwards (but to play it safe I’m using them for my AC and DC cables anyway, even though they’re all under 3 meters in length). But for UTP cables I don’t think anyone would care either way.

I run all my cables mounted to a board, or in “free air” in case of the UTP cables.

I’m only halfway through (waiting on the batteries to make up the DC cables), but this is what my setup looks like right now:

PXL_20250928_093703325
PXL_20250928_0937033251693×1275 453 KB

19

Thanks, but, Isn’t it mandatory to get them in red and black for AREI?

As for UTP, they care, they have to be Cca. I have bought 100m from Rexel which is Cca compliant.

20

If I’m not mistaken, an electric cabinet can only be fed from a single power source.
Which would mean the AC In and AC Out from a Multi can not arrive in the same fuse box.