What if your grid connection upgrade is refused or delayed?

Have you asked your grid operator for a heavier connection and got a long wait, a flexible connection or the request to build a customer cabin? Then you have more options than waiting. You can accept a flexible connection or control your consumption more smartly. You can also place a battery behind your existing connection to catch the peaks, or run part of your installation as a semi off-grid system. Which option fits depends on your measured quarter-hour profile. Once you know it, you know how much extra power you really need and for how long. That can be less than what was on the request.

Waiting is not free either. The study is already paid, the new machine or charge points are on order, and a classic upgrade in a congestion zone only comes after grid investments that can take years. The obvious fix, asking for more kVA, is exactly the one that depends on the grid.

How do you request a heavier connection in Flanders?

In Flanders you apply online. According to the Fluvius step-by-step plan:

• You start the request on mijn.fluvius.be and answer the questions about the power you need.
• You receive an email with a tracking code.
• Fluvius sends one or more quotes, which you accept or refuse.
• Once you agree and the preparatory works are done, Fluvius makes an appointment.

For a business there is more to it. To quote for a power of 25 kVA or more, Fluvius first carries out a detailed study. According to the 2026 customer requests tariff sheet, that study costs 493.90 euro excluding VAT for a power between 56 and 1,000 kVA. You pay it even if you do not accept the quote (Fluvius tariffs). That study decides whether you get a classic upgrade, a flexible connection or a connection to high voltage.

Considering a commercial battery as an alternative? Have it assessed before the request goes out.

When do you stay on low voltage, and when do you need a cabin?

The requested connection power decides which grid you end up on. The Fluvius tariff sheet puts it like this:

If you want to raise your connection power above 250 kVA in Flanders, you invest in your own customer cabin, with inspections and maintenance. What that involves, and when a battery is faster, is in our article on a medium-voltage cabin or a battery.

The extra power itself also has a price. On low voltage in 2026 Fluvius charges an additional power fee of 27.59 euro per kVA (excluding VAT) above 17.3 kVA. The first 100 metres of cable on public land are included. Above 56 kVA Fluvius can charge grid reinforcement beyond those 100 metres at a flat rate. Still looking for a building? Read first how to check the grid connection of a business building before you buy or rent it.

What is grid congestion?

Grid congestion is a local and temporary shortage of transport capacity on the electricity grid. At that spot the grid cannot carry all the requested capacity at the same time. Grid congestion does not mean there is too little electricity. It is about the capacity of the grid at that location (Fluvius).

What does grid congestion mean for your request in Flanders?

For your request, what counts most is where your site is and how much power you ask for.

Good to know:

• According to the Fluvius FAQ, there is no effective grid congestion today, but there is expected congestion in certain zones.
• Households are not affected. It concerns businesses on the medium-voltage grid. If you ask for a power for which Fluvius connects you to high voltage, it applies to you too.
• Fluvius publishes a map and figures. In orange zones only flexible connections are possible. In yellow zones, anyone asking for 1 MVA or more extra power gets a flexible connection. In green zones classic connections are still possible. Fluvius calls the map indicative and not binding.

The figures page (update of 15 September 2026) shows 335 requests for a classic connection and 327 requests with flexibility still waiting for a quote. Voka reported in April 2026 that almost 800 Flemish companies were waiting for a heavier connection. So check first which zone your site is in.

What is a flexible connection (Fall-Back Flex)?

Fall-Back Flex is the temporary flexible connection Fluvius offers to businesses on medium voltage (typically 100 kVA and more) in zones with expected congestion. You get the full requested power, but Fluvius can ask you to limit that power temporarily when grid safety is under pressure.

What to know before you sign:

• Not mandatory. You can refuse, but Fluvius can then postpone your connection or upgrade until the necessary grid investments are done.
• No fixed price. The cost depends on power, location and grid capacity, among other things, based on regulated tariffs.
• Netflex box. Fluvius supplies a Netflex box to pass on the limitation; your installer fits it.
• Temporary. Once the regulatory framework for flexible connection agreements is in place, your connection is converted automatically. The Vlaamse Nutsregulator held a consultation on it from 24 April to 27 May 2026. In BESL-2026-33 the regulator writes that the terms of those later agreements are not yet known.

Voka gives as an example a limitation of a few hours per month, or in extreme situations a few days per year. For a business that produces around the clock, the question is: what does your installation do at that moment?

What about Wallonia and Brussels?

In Wallonia the problem is the same, the rules come from ORES. According to ORES, several Walloon zones already carry a high risk of congestion. Access-to-power problems concern requests for a new connection or a power increase above 56 kVA. Where power is not always available, ORES can offer a connection with flexible power for needs above 250 kVA. ORES also warns that designing, permitting and building new grid installations sometimes takes several years.

ORES gives three pieces of advice: file a detailed study request as soon as your project is defined, match the requested power to your real needs, and consider internal flexibility such as smart load management, storage batteries and self-consumption. In Brussels the grid operator is Sibelga; ask it for the conditions at your site. A Walloon example of the most extreme case, a farm without any grid connection in the street, is our off-grid farm in St-Georges-sur-Meuse. For the Walloon procedure step by step, read how a business connection with ORES or RESA works, and what a flexible connection above 250 kVA is.

What are your alternatives if your upgrade is refused or delayed?

A battery is often the faster answer when the grid operator says no or asks for a cabin. Your existing connection supplies the base power, the battery the difference when you need more. In a Victron system the GX controller does that. With the peak shaving function of Victron ESS it watches the current at the energy meter (Victron). The battery steps in as soon as the set limit is at risk, also for charge points and heat pumps connected in parallel. With our monitoring you follow the system in real time.

Charge points are often the reason for the request. For that specific case, read our article on charge points for your business without a heavier connection. Is it a pump or a heavy machine? Then read how to get more power without a grid upgrade. Opening a hotel and the connection comes too late? Read how a hotel can open when the grid connection is refused or delayed.

One nuance: every storage system has to be notified to the grid operator. In Flanders you notify Fluvius; above 25 kVA of inverter power (three-phase) a notification is not enough and a grid study follows. In Wallonia a battery is among the new installations to declare to ORES, and above 10 kVA a more thorough study is needed (ORES).

How much battery does an SME need to avoid an upgrade?

The figures below are illustrative and internally consistent, not a customer case.

A business has a low-voltage connection of 100 kVA. It wants to add two 22 kW charge points and an extra 40 kW machine. Added up on paper: 84 kW extra, so a request towards 200 kVA. With that, the grid operator decides whether it stays low voltage or becomes high voltage, and in a congestion zone it can mean a flexible connection.

The measured quarter-hour values of the past year show something else:

• Highest quarter-hour peak today: 70 kW. Average during the day: 45 kW.
• With controlled charging and the new machine, we simulate a new highest peak of 125 kW, for eight quarter-hours (two hours) in the morning. After the peak, consumption drops to 50 kW.
• Safe limit on the existing connection: 90 kW, so a margin remains.

The business stays on its existing connection, the peak at the meter stays below 90 kW and the upgrade is not needed for this expansion. Because the inverter is above 25 kVA, the battery itself does need a grid study in Flanders (in Wallonia above 10 kVA). Plan that into the timeline.

If the profile shows peaks lasting many hours a day, then an upgrade or cabin is the right choice. That is why we calculate first.

What makes the difference between a battery and a real backup system?

If you accept a flexible connection, think one step further: security of supply is an engineering question, not a product purchase.

A system with off-grid capability takes over the supply when the grid drops out. Critical loads (cooling, servers, controls, milking installation) keep running. In our semi off-grid approach an automatic transfer switch switches between the public grid and the off-grid installation; the grid acts as the generator there.

One example is the flax processing company in Wielsbeke. Working on the public grid there would need a large medium-voltage cabin. The company starts its heavy machine with a generator that keeps running during the work, and that generator charges a battery.