Fluvius is the distribution system operator (DSO) for Flanders. If your site is in Flanders, your capacity tariff is set by Fluvius. This article explains how it works: how the 15-minute peak is measured, how it appears on your invoice, how to access interval data, and what to do when the stated peak seems wrong. Typical capacity rates for Flemish SMEs range from roughly €3 to €5 per kW per month depending on your connection class and tariff year-check your invoice or Fluvius published tariffs for your exact rate.
1. How Fluvius measures your peak
Fluvius uses digital meters that record your power draw every 15 minutes. Each interval produces an average kW value. At the end of the month, the highest of those values becomes your monthly peak. That peak is multiplied by the capacity tariff rate (€/kW) to determine your capacity charge.
The logic is identical across Belgian DSOs: one spike in any 15-minute window sets the charge for the whole month. If several heavy loads (HVAC, compressors, process lines) start in the same quarter-hour, that overlap drives your peak-even if your total kWh is unchanged. For more on why peaks can rise while consumption stays stable, read our guide on Fluvius digital meter peak reasons.
2. Where to find the peak on your invoice
The capacity component is usually in a section labelled "netbeheer" or "distributie". Look for terms like "capactarief" or "piek". The invoice will show your measured peak in kW and the €/kW rate applied. Your supplier may pass through the Fluvius charge or add a margin-check your contract.
If the stated peak seems far above what your site could physically draw-for example, higher than your main breaker or transformer rating-check the billing period and EAN first. A wrong period or wrong EAN can cause a mismatch. If those are correct, request the 15-minute interval curve from Fluvius and use it as evidence in a dispute with your supplier.
3. Common Fluvius invoice terms
Invoice terms
| Term | Meaning |
|---|---|
| Capactarief / Capaciteitstarief | The capacity tariff rate (€/kW). |
| Piek / Piekvermogen | The measured peak in kW. |
| Netbeheer / Distributie | The distribution/network section where capacity charges appear. |
| Puissance souscrite | Subscribed capacity (French term). |
Your supplier invoice may use Dutch, French, or a mix-the underlying logic is the same.
4. Accessing interval data
Fluvius provides interval data through its online portal (mijn.fluvius.be) and data services. You can request the 15-minute curve for your meter. Use it to verify the stated peak on your invoice, to identify which interval set your monthly peak (and at what time), to plan load staggering with operations, and as evidence in disputes if the peak seems wrong.
If you have multiple metering points (e.g. multiple buildings or EANs), request the curve for each. That way you can see which site drives your overall peak and where to focus stagger rules.
5. Reducing your Fluvius capacity cost
The same principles apply as elsewhere: stagger heavy loads so they do not overlap in the same 15-minute window. Map your startup windows (first hour, post-break, end-of-day) and introduce stagger rules. Use 10–20 minute offsets for flexible systems like EV charging, ventilation, and hot water. For a step-by-step playbook, read our guide on how to reduce peak demand charges. how to reduce peak demand charges.
6. Broader context
The capacity tariff logic (15-minute peak) is consistent across Belgian DSOs. Fluvius covers Flanders; ORES and Resa cover Wallonia; Sibelga covers Brussels. Each publishes its own tariff and has its own portal. For a complete overview of the capacity tariff in Belgium, read our capacity tariff Belgium guide. capacity tariff Belgium guide.
Key takeaways
- 1. Your Fluvius peak is the highest 15-minute average kW in the month.
- 2. Find the capacity line under netbeheer/distributie; look for capactarief or piek.
- 3. Request the 15-minute curve from the Fluvius portal to verify or dispute.
- 4. Stagger heavy loads to reduce peak concentration and capacity cost.