What does a peak cost a business in Wallonia and Brussels?

Yes, but only for businesses whose peak is measured. In Wallonia, ORES and RESA bill a capacity term on the eleventh highest quarter-hour of each month. They add a term on the highest monthly peak of the past year. In Brussels, Sibelga bills the single highest quarter-hour in peak hours of the past 12 months. Smaller connections up to 56 kVA pay no peak-based charge in either region. For a site with peak metering, a business battery system can cover those few quarter-hours and lower the network cost for a full year.

Maybe you run a workshop in Namur, a cold store near Liège or offices in Anderlecht. You searched for the capacity tariff and found pages about Fluvius and Flanders. Your own invoice shows other words: a "terme capacitaire", a "pointe mensuelle", a "pointe annuelle", or a peak in "kW HI". Nobody explains which quarter-hour set that number, or why it stays on your bill for months.

What most managers do not see is how long one busy moment lasts on the bill. In Brussels, a single quarter-hour in peak hours sets the capacity charge for the next twelve months. In Wallonia, one bad month raises a third of the capacity term for a year. A compressor, an oven and the van chargers starting together can do that. Many of these peaks are short. They are cheap to avoid and expensive to ignore.

The most radical answer is to need no grid at all. A farm in St-Georges-sur-Meuse had no electricity connection in its street and ran on a generator. It now runs fully off-grid on solar panels and a 46.2 kWh battery, with the generator only as back-up. Most businesses will stay on the grid. For them, the point is to know which quarter-hours they pay for.

Is there a capacity tariff in Wallonia?

Yes, for businesses whose peak can be measured: medium voltage and low voltage above 56 kVA. Smaller low-voltage connections up to 56 kVA pay no capacity term in 2026 to 2029. The Walloon regulator CWaPE approved the distribution tariffs of ORES, RESA, AIEG and AIESH for 2026 to 2029 on 26 June 2025. The tariffs of REW followed later.

IMPACT is only open to connections up to 56 kVA with an active communicating meter. So a small business in Wallonia gains nothing from lowering its peak today. It gains from moving use to the cheaper hours, which we cover below.

How do ORES and RESA calculate the peak of a business?

ORES and RESA use the same rule: the monthly peak is the eleventh highest quarter-hour of the month. The annual peak is the highest monthly peak of the last twelve months, the current month included. ORES bills two thirds of the capacity term on the monthly peak and one third on the annual peak.

Two things follow from that rule. The ten highest quarter-hours of a month are free. A one-off start-up or a single test does not set your monthly peak. But a load that runs above your usual level for eleven quarter-hours or more does, even spread over the month.

Second, one bad month stays with you. If March sets your highest monthly peak, that March peak is the annual peak until February of the next year. A battery or load control that lets one busy month through still pays that annual peak for a year.

Three more rules sit in the same tariff sheets. There is no maximum price on the capacity terms. A back-up supply used at most 500 hours a year pays no capacity term. And when the grid operator activates flexibility on a flexible connection, the power it asked for is deducted from the peak of that quarter-hour.

Our guide on how to read and lower your business peak demand shows how to find those quarter-hours in your data.

What does a kW of peak cost with ORES and RESA in 2026?

In 2026, a kW in the monthly peak costs about 2.79 to 8.12 euro per month on medium voltage and larger low voltage. The annual peak adds half that rate again, every month. Low voltage above 56 kVA pays more per kW than medium voltage.

On medium voltage, the kWh part is small by comparison. The distribution tariff per kWh stays well below one cent at ORES and RESA. That is why the peak matters so much on these connections.

The regulator also shows what a whole year costs a typical medium-voltage business. Its reference site uses 2 GWh a year with a peak of 333.2 kW. The same site pays quite different amounts depending on where it is connected:

Your grid operator is set by your address, not by choice. What you can influence is the size of the peak you hand them.

Is there a capacity tariff in Brussels, and how does Sibelga bill the peak of a business?

Yes, in two forms. Small connections pay a fixed capacity amount, and sites with peak metering pay for their highest quarter-hour in peak hours. The Brussels regulator Brugel approves the tariffs of Sibelga.

• Low voltage up to 56 kVA without peak metering: a fixed amount set by the power made available to you. In 2026 that is 47.24 euro a year up to 13 kVA and 94.48 euro a year above 13 kVA, excl. VAT. Your measured peak does not change it.
• Low voltage above 56 kVA with peak metering: 66.87 euro per kW per year in 2026, charged per day and billed monthly.
• Medium voltage: 59.98 euro per kW per year in 2026, multiplied by a discount coefficient that shrinks for large peaks.

The Brussels rule for the kW is strict. Sibelga bills the highest quarter-hour you took from the grid in peak hours during the last 12 months, the billing month included. One quarter-hour is enough, and it stays for a year.

The upside is the calendar. Off-peak hours in Brussels run from 22:00 to 7:00 on weekdays and all day on Saturdays, Sundays and public holidays. A peak at night or at the weekend does not count for the capacity charge.

Medium-voltage sites in Brussels also pay a public service contribution based on the power of their connection. Sibelga lets them announce a change in the power made available until the end of June, for January of the next year.

Wallonia or Brussels: what does one busy month cost?

One extra kW that lasts long enough to count costs between about 20 and 67 euro over the next twelve months. The difference comes from the region and the voltage level. It assumes that the busy month becomes the highest peak of the year.

Take 50 kW of extra peak: a new compressor, or two chargers that start with the ovens. On low voltage above 56 kVA in Brussels, one quarter-hour of that in peak hours costs about 3,300 euro over the next year. At ORES on the same voltage it costs about 2,500 euro, but only if it happens in eleven quarter-hours or more that month.

Which hours are cheaper on the grid for a business in Wallonia and Brussels?

The kWh part of the network tariff has cheaper hours in both regions, but they are not the same hours. Wallonia added a midday off-peak period for low voltage in 2026. Medium voltage and Brussels keep the classic night and weekend off-peak hours.

For a Walloon business on low voltage, the new midday off-peak window sits right on top of solar production. Charging vans, pre-cooling a cold room or heating water between 11:00 and 17:00 now costs less network tariff. The time bands of your energy contract are a separate matter, so check both.

What changes for business grid tariffs in Wallonia and Brussels up to 2030?

Three changes are already decided. The large-site discount fades, Brussels brings a capacity tariff to small connections, and the Walloon grid budget grows.

When does a battery lower network costs for a business in Wallonia or Brussels?

A battery lowers network costs when your peak is measured and comes from short, repeatable spikes. Think of compressors, ovens, lifts, welders or chargers that start together. It does little for small connections, and nothing for a load that runs flat out all day.

• Good fit: medium voltage or low voltage above 56 kVA, with a peak set by a few busy hours. The battery delivers the kW above a limit you choose and recharges in quieter or off-peak hours.
• Good fit in Brussels: a battery that charges at night or at the weekend does not add to your billed peak. Those hours are off-peak.
• Weak fit: low voltage up to 56 kVA in Wallonia or Brussels today. There is no peak charge to lower, so a battery must pay off on solar self-consumption, cheaper hours or back-up instead.
• No fit: a load that stays high for most of the day. The battery cannot recharge under the limit, so a heavier connection or another setup fits better.

The control makes or breaks the saving. In Wallonia, the battery can let ten quarter-hours a month through and focus on the rest. In Brussels, it must hold the limit in every peak-hour quarter-hour. Our energy management systems for businesses guide explains how that control and the monitoring work.

Does your cabin transformer also sit at its limit? Then read our article on what to do when the transformer in your cabin is too small. Our guide on peak shaving with a battery covers sizing in kW and kWh.

What happens when you ask us to look at your network costs?

We start with your invoice and your quarter-hour data, not with a battery.

1. Step 1: Analysis and sizing. We read your tariff category, your peaks and which quarter-hours count in your region. If data is missing, we can measure your consumption for a short period first.
2. Step 2: Technical design. We size the battery in kW and kWh and set the control to the rule of ORES, RESA, another Walloon operator or Sibelga.
3. Step 3: Installation and commissioning. Our business battery installations are modular up to 1 MW and include monitoring, control and optimisation.
4. Step 4: Monitoring and support. You follow the system in our monitoring software, and we adjust the limit when your site changes.