In a full no-break house, the whole distribution board hangs on the uninterruptible output of the inverter-charger. The inverter separates the house from the grid and feeds it from the battery in a power cut. A battery backup for home on this level is a wiring project. It needs a back-up board, a clean changeover, local earthing in island mode and a new inspection.
You live in a large house with an electric gate, an alarm, a heat pump and maybe a home lift. In the last power cut the gate stayed shut and the alarm kept beeping on its small battery. So you want "the whole house on the battery". Then you find out it is not a box you plug in. A Dutch owner on a forum dropped back-up because it meant a big rebuild of the meter cabinet: "too much hassle (and far too expensive)".
What most quotes leave out is that full back-up changes the heart of your installation. The inverter becomes the new supply of the house. Your RCDs must work without the grid, and the neutral needs an earth in island mode. The grid must never get power back from your battery. On a Belgian forum, owners argued whether a home-made changeover would pass inspection. One warned: "Heaven help you if you ever switch both fuses on at the same time." Planning the board late means rebuilding it twice.
In a house in Sint-Niklaas the electrical enclosure was outdated. We adapted it to more modern standards, and the house now runs on full back-up from solar panels and a 15.4 kWh battery.
What does full no-break mean in the wiring of a house?
Every circuit of the house is fed from the inverter output, not straight from the grid. When the grid fails, the inverter keeps that output alive from the battery and the solar panels.
How a full no-break house is wired
| Set-up | What keeps working in a power cut | Typical use |
|---|---|---|
| Full no-break | The whole house | Large homes, home offices, lifts and gates, remote houses |
| Partial back-up | Only the circuits on the back-up board | When heavy loads such as an EV charger must stay on the grid side |
| No back-up | Nothing: the battery stops with the grid | Battery used only to store solar power |
Not sure yet which battery you need for back-up? Start with our guide to a home battery with backup power. On three phases, read how much power a three-phase home battery gives per phase.
Which switchboard layout does a full no-break house need?
Either the whole board goes behind the inverter, or the board is split into a back-up part and a grid-only part. The choice depends on your largest loads and on the inverter power.
In a full no-break house, the current of the whole house runs through the transfer switch inside the inverter. On a Victron MultiPlus-II, that switch is rated 50 A on the 5 kVA model. The 8, 10 and 15 kVA models have 100 A. The main breaker of the house, the cable and the inverter must fit together. With PowerAssist, the inverter adds battery power when the house asks more than the grid input gives.
| Layout | How it works | Watch out for |
|---|---|---|
| Whole board on the inverter output | One board, all circuits no-break | Transfer switch rating, inverter power for the biggest loads |
| Split board | Essential circuits on a back-up board, heavy loads on a grid-side board | Clear labels: which sockets work in a power cut? |
| Second output (AC-out-2) | Loads that may only run with the grid, switched off in battery mode | They come back about 2 minutes after the grid returns |
Victron gives an electric water heater or an air conditioner as examples for that second output. They should not empty the battery. In a large home, the same logic often applies to a sauna or a pool heater.
Gates, lifts and alarms: what must a large home keep running?
First list what must never stop, then check the start current of each motor. A gate or a lift that does not start on the inverter is worse than one on the grid.
| Load | Why it matters in a power cut | Check before wiring |
|---|---|---|
| Gate and garage door motors | You can get your car in and out | Start current, and whether the motor has a manual release |
| Alarm, cameras, access control | Their small standby battery runs flat in a long outage | Put them on the back-up board, not on a separate adapter |
| Home lift | Nobody gets stuck between floors | Ask the lift supplier whether it may run on an inverter and what it draws at start |
| Heat pump and heating controls | Heat and hot water in winter | Start current and phase; see the heat pump article |
| Well, sump and sewage pumps | No flooded cellar, working toilets | Start current; a forum owner needed his 500 W lift pump above all |
| Network, router, home office | Work and remote monitoring keep running | Small load, high priority |
| EV charger | Can empty a home battery in hours | Often better on the grid side or limited in battery mode |
Read how a heat pump runs on a home battery in winter and in a power cut before you put it on the back-up board.
How does the changeover from grid to battery work?
In a full no-break house, the changeover is the transfer switch inside the inverter-charger. Victron states it takes over in less than 20 milliseconds, fast enough for computers.
Two things must happen at the same moment. The house keeps its power, and the grid gets none of it back. The Belgian electrical code (AREI) sets how an own source must separate from the grid. For sources up to 30 kVA, an automatic separation system may be used. It has two elements in series, one of them an all-pole automatic switch. It must make a galvanic separation within 5 seconds after the grid fails. The Synergrid C10/11 rules add that, in a small installation, this automatic separation system also does the job of the safety disconnect.
This protects the people who repair the street cable. A home-made switch with two breakers can put your battery on a grid that line workers think is dead. That is why the changeover belongs inside certified equipment, not in a DIY box.
Want a generator as a second line for long outages? It connects to the inverter input, not to a socket. In Maaseik the home battery got an off-grid mode that allows connecting the generator that was already there. The GX controller can start a back-up generator automatically.
Tip
Ask how the house is fed when the inverter itself needs service. A manual bypass switch lets the house run on the grid while the inverter is out.
Why does the earthing change when the house runs on the battery?
In a power cut, the inverter makes its own small grid, and its neutral must then be linked to earth inside the house. Without that link, a residual current device (RCD) may not trip on a fault.
The Synergrid C10/11 rules forbid earthing the neutral of an own source while it runs parallel with the grid, unless a transformer separates it. In island mode, a local earth link is allowed. That link must open again before the house goes back on the grid, and stay locked open while it is connected.
The Victron MultiPlus-II does this with a built-in ground relay. It connects the neutral output to the chassis when there is no grid. When the grid returns, the relay opens before the input relay closes. Victron writes that this ensures the correct operation of an RCD on the output. On a French forum, one member warned another that with a floating neutral in island mode, the 30 mA RCDs are useless.
The earth electrode of your house stays the only earth. The inspector measures it, so an old or weak earth connection shows up at inspection.
Which protection belongs on the back-up board?
The back-up board is a full distribution board, fed by the inverter: it needs its own RCD and breakers behind the inverter output. Victron requires an RCD and a fuse or breaker in series with the output.
| Protection | Rule or source | What it means for the no-break board |
|---|---|---|
| Fuse or breaker on the inverter input | Victron manual: 50 A or less on the 5 kVA model | Sized to the cable and the grid input |
| RCD and breaker on the inverter output | Victron manual | Protects the back-up board in battery mode |
| RCD of at most 300 mA at the origin | AREI 4.2.4.3 | The main RCD at the start of the installation stays |
| High-sensitivity RCD for sockets, lighting, bathrooms, washing machines, dryers and dishwashers | AREI 4.2.4.3 | Maximum 8 final circuits per such RCD, also on the back-up board |
| Ground relay for island mode | Victron manual, C10/11 7.4 | Neutral earthed only while islanded |
| Surge protection | Good practice | See our article on surge protection |
Victron notes that the inverter has a mains-frequency transformer, so type A RCDs can be used on its output. Long cable runs to a garage or an outbuilding also pick up surges from lightning. Read how to protect solar panels and a battery against surges.
Want the whole house on the battery? Send us a photo of your distribution board and a list of the loads that must keep running.
Does a full no-break house need a new AREI inspection?
Yes, in practice. The AREI calls a change that adds a new safety impact an "important modification", and every important modification needs a conformity inspection before use.
The AREI gives examples that match a no-break rebuild almost word for word:
- A change of the earthing system.
- A non-identical replacement of a distribution board.
- Adding a circuit in a household installation.
The inspection covers the added or changed part. The person who does the work draws up the single-line diagrams and the situation plans. In Flanders, you report the battery to Fluvius with a valid AREI inspection and a clear single-line diagram of the battery. So the diagram must show the back-up board, the RCDs and the separation from the grid. Read how to register a home battery in Belgium for the reporting steps.
How do we wire a full no-break house?
We start from the loads that must keep running and from the board you have today. Then we choose the inverter, the board layout and the battery around them.
In Peer the customer is an electrician himself; the entire house is on no-break on a single-phase connection, 5 kVA and 15.4 kWh. In Wetteren we built a full no-break on three phases: 9 kVA and 15.4 kWh, and everything keeps working when the grid fails. In Temse a single-phase house has full back-up, and in Hasselt we built the control panel into the distribution board.
- Step 1: We measure your consumption and list the loads that must run in a power cut: gate, alarm, lift, heat pump, pumps, network.
- Step 2: We look at the board. Can it go behind the inverter as it is, or does it need a split or a modernisation, as in Sint-Niklaas?
- Step 3: We choose the inverter power per phase, the transfer switch rating and the battery size. The battery modules are expandable.
- Step 4: We wire the back-up board with its RCDs, the separation from the grid and the earthing for island mode. Then we draw the single-line diagram.
- Step 5: After the AREI inspection, the battery is reported to the grid operator. You follow the system in the free VRM app and portal.
Our team has three certified battery specialists. Is the only good place for the battery outside? Read whether a large home battery can stand outside, or see what our home batteries can do for a large home.
Frequently asked questions
Can I keep my existing distribution board?
Often yes, if it is in good condition and fits behind the inverter. An outdated board is best modernised first, as we did in Sint-Niklaas. Any non-identical replacement counts as an important modification.
Do my solar panels keep working in a power cut?
Only when they are connected so that the inverter can keep them running in island mode. A normal grid-tied inverter switches off with the grid. Read which home battery works off-grid.
Can my own electrician do the wiring?
Yes, as in Peer, where the customer is an electrician himself and we brought the battery know-how. The changeover, earthing and settings of the inverter must match the board, so both must work from one diagram.
What happens when the battery is empty?
The house goes dark until the grid, the sun or a generator returns. A generator on the inverter input, started by the GX controller, bridges long outages.
Want your whole house on the battery?
Send us a photo of your distribution board, your connection type (single-phase or three-phase) and the loads that must keep running. One of our battery specialists will tell you which layout works and what the rebuild involves. First want to compare with a three-phase home battery for full back-up?