Choose an installer for off-grid or battery storage who measures your use and visits the site before sizing anything. The right one is clear about the AREI inspection and the grid notification, installs an open system, shows projects like yours and services it afterwards. Our off-grid solutions page shows which route fits your site.
The grid operator said no, or the cabin quote came in. Or three quotes on your desk look alike, and you cannot see the forest for the trees anymore. The cheapest general installer is often the most expensive choice for an off-grid or business job.
Which kind of company do you need for off-grid, semi-off-grid or a battery?
The kind of company depends on the project, not on the battery brand. A standard home battery next to existing solar panels is a job for a good electrician or solar installer. Off-grid, semi-off-grid and business batteries need a battery specialist who also designs the whole system.
| Your situation | Company you need | What to check first | Where to read on |
|---|---|---|---|
| No grid connection, or the connection is refused | Off-grid specialist | Winter sizing, generator as back-up, AREI file | Off-grid system |
| Connection too small or weak grid, peaks you cannot cover | Semi-off-grid specialist | Switching between grid and battery, what keeps running in a power cut | Semi-off-grid system |
| Business with peaks, chargers or heavy machines | Business battery specialist | Measured peaks, grid study above 25 kVA, integration with what is there | Business battery |
| Large or all-electric home with full back-up | Battery specialist | Three-phase experience, back-up tested with you | Home battery |
| Simple home battery on standard solar panels | Good electrician or solar installer | AREI inspection and Fluvius notification arranged | Section on when you do not need a specialist |
Read on per route: off grid system, semi off-grid system, business battery or home battery.
The obvious grid fix is not cheap either. In Beernem, a grid study, a disconnection panel and maybe a medium-voltage cabin could have cost up to 30,000 euro.
Public bodies usually run a tender: our article on how a public body buys a battery system explains the specifications and the framework contracts.
What should a good installer do before giving you a quote?
A good installer measures your real use and looks at your site before sizing anything. A quote that arrives after one phone call is a guess. For off-grid and business systems, that guess decides whether you run short in January.
We measure the actual and the peak consumption over a given period. From those figures we size everything: the generator, the battery, the inverters and the cables. For a home battery too, the measurements come first.
From practice
In Zele, a landscaper was still building his home and warehouse, so nobody knew the future use. We monitored his average and peak use for one month first. Only then did we match the number of solar panels to the real use.
Who may install a battery, and is RESCert required?
A battery is installed by a professional, inspected under the AREI and, when you stay on the grid, notified to your grid operator. AREI is the Belgian electrical safety code. Before you sign, ask who books each step, and get the answer in writing.
In Flanders, a home battery is fixed to the electrical installation by an installer and inspected by a recognised inspection body. You then notify it to Fluvius within 30 days after that inspection, online in Mijn Fluvius. Since 1 January 2017, every grid user must report a storage system.
| Region | Inspection | Notification |
|---|---|---|
| Flanders | AREI inspection by a recognised body before use | Fluvius within 30 days after the inspection; up to 25 kVA in Mijn Fluvius, larger systems through a grid study |
| Wallonia | RGIE inspection (the French name of the AREI) by a recognised body | Declaring panels and batteries to ORES is a legal obligation |
| Brussels | AREI/RGIE inspection by a recognised body | Ask Sibelga, your grid operator, before you start |
| Off-grid site, all regions | AREI inspection before use, also when a generator feeds the site | In Flanders, island installations of 800 VA or more go to the VNR, not Fluvius |
For a business, the inspection is not a one-off: a non-household installation is inspected again every 5 years. What the inspector checks on an off-grid site is in our article on the AREI inspection of an off-grid installation. For a home battery, read how to register a home battery in Belgium.
RESCert is not the proof to ask for: it lists no category for batteries or storage. It certifies installers of solar panels, solar water heating, biomass, heat pumps and shallow geothermal systems. A RESCert installer can be a fine solar installer, but that says nothing about battery design.
Watch out
Some Belgian comparison pages still tell you to ask a battery installer for RESCert. Ask for proof that fits the job instead. Think of battery training, certification by the battery or inverter maker, earlier inspection reports and projects like yours.
We are a Victron Energy Certified Partner and installer, and the team has three qualified battery specialists.
What should an off-grid or business battery installer check?
An off-grid installer sizes on your peaks and on winter, and treats the generator as back-up, not as the main source. A semi-off-grid installer also knows when the grid is better used as a charger. A business battery installer checks your measured peaks, your connection and everything already on site.
Our first project, Special Renting in Zele, rents out electric lifting gear and runs 100% without the public grid. The grid study offered no connection. The site now runs on 30 kWp of solar panels, a battery system and a generator for dark, busy periods.
In St-Georges-sur-Meuse, the street had no connection and the farm ran fully on a generator. With solar panels and a battery of 46.2 kWh, the generator now only serves as back-up.
Heavy machines change the design. A flax processing company in Wielsbeke would have needed a medium-voltage cabin on the grid. The generator that already starts the machine now also charges the batteries, 3 x 8 kVA with 30.8 kWh.
In Gedinne, a weak grid left only 180 V on 3 x 230 V. The semi-off-grid system brings it to 3 x 400 V and keeps the grid as a charger for the battery. In Maasmechelen, the customer picks the street or his existing generator as the charger.
Whether off-grid pays off for your company is answered in our article on when off-grid pays off for a business. How the generator and the battery share the work is in generator and battery off-grid.
Solar panels, chargers and machines all change how a business battery must behave. Ask its installer three things:
- Do you size on our quarter-hour peaks, not on our yearly use?
- Does the plan stay under 25 kVA, or does it need a Fluvius grid study?
- How does the battery work with our existing installation and chargers?
We build modular business systems up to 1 MW, with chargers up to 180 kVA on Victron power. Monitoring, control and optimisation are included. For a business, the installer you pick is also the one you call when production stops.
How long a business project takes, from the first visit to the switch-on, is in our business battery project steps.
Which questions help you choose an installer for off-grid or battery storage?
Ask every installer the same ten questions about the company and its way of working, and compare the answers side by side.
| Question | Good answer | Red flag |
|---|---|---|
| Will you measure our use before sizing? | Yes, over a period, average and peaks | A size from the yearly bill only |
| Will you visit the site before the quote? | Yes, with photos and questions about loads | A quote after one phone call |
| Who books the AREI inspection? | A clear name and step in the plan | "Not needed" or "your problem" |
| Who files the Fluvius, ORES or VNR notification? | A clear name and step | No answer |
| Which projects like ours have you built? | Named projects of the same type | Only home batteries for a business job |
| Who does the battery work, and what training do they have? | Named people, battery training, maker certification | Only a RESCert logo |
| Can another company read and service the system? | Yes: open parts, monitoring shared with you | Closed system, access only via the installer |
| What do we get at handover? | Diagrams, settings, inspection report, monitoring access | An app login and nothing else |
| Who do we call when something fails? | A named service route | A general mailbox |
| What happens to the battery at the end of its life? | A take-back or recycling route | "We will see" |
Price comes after these questions, not before. Already have business quotes? Our guide to comparing business battery quotes checks them line by line.
Working with your own electrician? Read how an electrician and a battery specialist work together.
Want these ten questions answered for your site? Call us or send a message.
Who services the system later, and what happens at the end of the battery?
Another company can only service your system if it is open, the monitoring is shared with you and you get the papers at handover. Ask this before you sign: installers stop, move or refuse off-grid work because of the after-sales burden. You want a company that still answers the phone in five years.
An open system
Parts that another qualified installer can read, set and repair. Ask which brands are used and whether the settings can be read without the original installer.
Monitoring in your name
Victron VRM is free with a GX device and an internet connection. The owner can add users and revoke them later, and settings and firmware can be updated remotely.
Battery data you can read
Since 18 August 2024, the EU Battery Regulation requires the management system of stationary storage to hold its state of health. The owner, or a company acting for them, may read it.
The file of your installation
Single-line diagrams, position plans, the inspection report and the data sheets. The AREI requires this file, and the next installer starts from it.
If nobody else can read your system, you are not buying a battery, you are buying a dependence.
At handover, ask for a test of the back-up with you present, the file of the installation and your own monitoring login. Warranty terms belong in writing: the product warranty of each part from the maker and the workmanship warranty of the installer. Our articles on business battery warranty and maintenance and home battery lifespan and warranty list what to check.
Our after-sales service follows installations over the network. We also do maintenance and repairs on existing battery systems. And our Battery Disassembly Center dismantles and recycles lithium batteries.
Our article on old batteries and inverters explains what an installer must do with them, with the rules and the routes.
When don't you need a specialist?
You do not need a specialist for a standard home battery next to existing solar panels, on a normal connection without back-up or heavy loads. A good electrician or solar installer can place it, have it inspected and notify it.
Our verdict
Pick a local installer who arranges the inspection and the notification, and compare their quote with a group purchase. Our article on group purchase or specialist helps you decide. Call a specialist for off-grid, semi-off-grid, back-up, three-phase homes or a business.
Some customers are electricians themselves. In Peer, the customer is an electrician and the whole house runs on "no-break" with 15.4 kWh of storage. The battery know-how and his own finishing made a good combination.
In Flanders, plug-in batteries under 800 W are allowed since 17 April 2025 and need no installer. Our article on what a plug-in battery cannot do explains the limits. A fixed home battery you place yourself still needs an AREI inspection and a notification: read whether you can install a home battery yourself.
Frequently asked questions
Which company is best for a home battery in Flanders?
No list can answer that for your home. Use the ten questions above and pick the company that measures, arranges the inspection and shows projects like yours. For large or all-electric homes, see our home battery page.
Which specialist can assess my project for a commercial battery in Flanders?
A battery specialist who measures and looks at your site before the quote. Prepare quarter-hour data from your digital meter, your single-line diagram, a list of heavy loads or chargers and any letter from your grid operator.
Is off-grid allowed in Belgium?
Yes. A site may run without a grid connection, but the installation is inspected under the AREI like any other. Our article on the AREI inspection of an off-grid installation explains the rules.
How do you find a reliable installer for a three-phase battery?
Ask for three-phase projects of the same size, like the home in Kortenberg on three-phase batteries with full back-up, 9 kVA and 30.8 kWh. More in our article on three-phase home batteries with back-up.
How does working with us look, from design to handover?
We guide the project from A to Z, as one partner from design to handover. You talk to the people who size, build and follow your system.
- Step 1: Analysis and sizing, on your measured actual and peak use.
- Step 2: Technical design. We draw the installation, choose the parts and plan the steps with you.
- Step 3: Installation and start-up. We build the system and start it up, with the AREI inspection before use.
- Step 4: Monitoring and support. You follow production, storage and use in the app, and we follow the installation over the network.
Want someone to measure and look at your site first? Tell us what must keep running, what connection you have and what the grid operator said. One of our battery specialists tells you honestly which route fits, whether you need a specialist at all and what we would measure first.
Our off-grid solutions page shows the routes side by side, with the projects behind them.
Sources
- Vlaanderen.be: home battery, installation, AREI inspection and notification
- Vlaanderen.be: plug-in solar panels and plug-in batteries in Flanders
- Fluvius: reporting a storage system
- RESCert: certified installers and technologies
- FOD Economie: inspections of non-household electrical installations
- Victron Energy: VRM Portal manual, introduction
- Victron Energy: VRM Portal manual, share your site
- EUR-Lex: Regulation (EU) 2023/1542 on batteries