Only when your winter peak plus the heat pump's maximum electrical input stays below the power of your business grid connection. That load is largest on the coldest morning. If it fits, control the heat pump so it sets no new peak. If not, choose a heavier connection, a medium voltage cabin or a business battery.
The workshop boiler is twenty years old, the gas contract is up, or head office wants the site off fossil fuel. The heat pump quote lists kW of heat and a COP, but rarely what happens on your meter.
In Zele, the warehouse of Special Renting Van Zele heats its floor with a heat pump and has no grid connection at all.
How much electricity does a heat pump for a business draw?
A heat pump draws its heat output divided by its COP (coefficient of performance: the kW of heat it makes from 1 kW of electricity). NIBE gives the example of an 8 kW heat pump at a COP of 4: at full output it draws 2 kW.
A heat pump that must deliver 60 kW of heat draws about 20 kW of electricity at a COP of 3. On a freezing morning the COP can fall to 2, and the same heat then takes about 30 kW.
Energuide writes that the COP falls in cold weather, and that between 2 °C and -7 °C outside your electricity use rises markedly. Energie+ (UCLouvain) flags the same trap for air-source heat pumps: their output falls when the building asks for more.
Most modern heat pumps have a built-in electric backup heater, Energuide writes. It kicks in when the heat pump can no longer meet the demand. An electric element turns one kW of electricity into one kW of heat, so it costs far more power than the heat pump itself.
Ask your heating installer for these numbers before you sign.
| Ask for | Why it matters |
|---|---|
| Maximum electrical input at the design temperature (kW) | This is what you add to your peak, not the heat output |
| Power of the electric backup heater, and when it switches on | It can add as much as the heat pump itself |
| Single-phase or three-phase, 230 V or 400 V, and the fuse rating | Sets which connection the unit needs |
| Can the power be limited or controlled from outside? | Lets a controller keep it under a limit |
| Does it also cool in summer? | Then it can set peaks all year |
How do you check whether your business grid connection can take a heat pump?
Your connection is strong enough when your highest peak plus the heat pump's maximum electrical input stays below your connection power, with some margin. Use your winter peak, not your average use. If the total goes above your connection, the main fuse trips.
Your connection is given in amperes. On 3 x 400 V, kVA = 1.73 x 400 V x amperes / 1000.
| Connection | Power (about) |
|---|---|
| 3 x 400 V, 40 A | 27.7 kVA |
| 3 x 400 V, 63 A | 43.6 kVA |
| 3 x 400 V, 80 A | 55.4 kVA |
| 3 x 400 V, 100 A | 69.3 kVA |
The digital meter shows this month's highest quarter-hour under code 1.6.0; Mijn Fluvius shows your peaks per month, so check January and February. Say your January peak is 30 kW on a 63 A connection (43.6 kVA). A heat pump drawing 20 kW on a cold morning brings you to 50 kW: that no longer fits.
Still on 3 x 230 V? Then many three-phase heat pumps will not even connect: read why, and your options, in a 3x230V connection that is too weak.
Watch out
In Flanders a connection up to 25 kVA is always low voltage. Between 25 and 250 kVA the grid operator decides, and above 250 kVA it is always high voltage with your own cabin. A big heat pump on a site already near the limit can push you over that line.
What does a heat pump do to your capacity tariff?
In Flanders a heat pump raises your capacity tariff for every month in which it raises your monthly peak. Fluvius takes the highest quarter-hour of each month, and you pay for the average of the last 12 monthly peaks. In 2026 that costs about 53.39 euro per kW per year on average (excl. VAT), with a minimum of 2.5 kW.
With 20 kW extra in the five coldest months of heating, your 12-month average rises about 8.3 kW (20 x 5 / 12). That costs about 445 euro a year. If it also cools in summer and raises the peak every month, the cost climbs to about 1,068 euro.
What 20 kW of extra heat pump peak costs per year in Flanders
The kWh the heat pump uses are one cost; the kW it adds at the same time as everything else are another. NIBE makes the same point for homes: a heat pump lowers your capacity tariff only if you spread use and avoid peaks. Our guide on how to calculate the capacity tariff for your business walks through the full calculation.
Watch out
On medium voltage you pay for a contracted access power plus your monthly peak. Going above it is charged for 12 months at 150% of the tariff. One cold morning over it costs you a full year.
Why does a business heat pump set its peak demand on the coldest morning?
Because several things happen in the same quarter-hour: it is cold, the building must warm up, and the working day starts. Each one alone is manageable; together they set your monthly peak, often on a cold Monday morning.
- The COP is at its lowest when it is coldest outside, so each kW of heat costs more electricity.
- The morning reheat. A building that cooled down overnight needs extra heat before the staff arrive.
- The backup heater switches on when the heat pump cannot keep up, often exactly on the coldest mornings.
- Everything else starts too: compressors, machines, lighting, and the vans on their chargers. Our article on business peak demand shows how to find that quarter-hour in your data.
Example: a warehouse with a heat pump on a cold working day
How do you add a heat pump without raising your peak?
Work from cheap to expensive: size it right, check the backup heater, shift the heating, cap it, and only then store energy.
Size it on the building, not on the coldest day
Energie+ advises sizing a bivalent heat pump (one that works with a second heat source) at 70 to 80% of the maximum heat demand. Keeping the old gas boiler for the coldest days covers the peak without electricity.
Keep the backup heater in check
Energuide advises not letting it switch on automatically where the manufacturer allows it. Switch it on by hand and watch the meter. Energids adds that switching it off completely can cause problems in frost, so agree this with your installer.
Heat steadily instead of catching up at seven
A heat pump uses less at a constant temperature; Energuide advises lowering the setpoint by at most one degree at night. A concrete floor or a buffer tank stores heat, so the heat pump works before the machines start.
Let a controller cap it
An energy management system can hold back flexible loads, such as a heat pump or chargers, when the site nears a limit you set.
Store for the part you cannot move
A business battery delivers the extra power during the cold morning and recharges when the site draws little. In a Victron system, peak shaving keeps grid offtake under a current limit you set. Our article on peak shaving with a battery explains how much power and energy that takes.
Planning a heat pump and not sure your connection can take it? Call us or send a message.
Heavier connection, medium voltage cabin or battery: which fits your site?
If the heat pump does not fit, choose by how many hours a year you are short, not by the size of the heat pump. Asking Fluvius for a heavier connection takes time and can end in a medium voltage cabin.
| Option | When it fits | Watch out |
|---|---|---|
| Size and control the heat pump | The total is close to your connection | Needs a heat pump that can be limited |
| Keep the gas boiler for the coldest days | You still have gas and a working boiler | You keep a gas connection and its fixed costs |
| Heavier low-voltage connection | The street has capacity and you can wait | Cost and waiting time; in congested areas it can be refused |
| Medium voltage cabin | Your site is growing far beyond 250 kVA anyway | About 40,000 to 75,000 euro on average (Inagro) |
| Business battery behind the meter | You are short for hours, not for days | Sized on the winter peak and the hours it lasts |
| Semi off-grid system | The connection is too weak for your plans | Most of the site runs on solar and battery |
Has Fluvius already refused a heavier connection? Then read your options when a heavier connection is refused.
Weighing a cabin against a battery? Our comparison of a medium voltage cabin or a battery sets out the costs.
A farm in Tielt shows the battery route. Its connection was too small to grow, and the next step would have been medium voltage. The battery system (45 kVA, 123.2 kWh) now gives the site more power, so a heavier connection was not needed.
A smart control sends surplus solar power to the boilers. Our semi off-grid system works on the same principle.
Our verdict
A small office with a heat pump of a few kW and room on its connection needs no battery. A battery makes sense when the heat pump pushes you over your connection part of the winter, or saves a heavier connection or cabin. It pays off faster when it also stores solar, lowers your peak all year or gives back-up power.
Can solar panels run a heat pump in winter?
Not on the coldest days. The heat pump needs the most power in December and January, exactly when solar panels produce the least. Solar covers a large share of the heating in spring and autumn, but not the January peak on its own.
At Van Zele, 30 kWp of solar panels and a battery carry the site most of the year. A generator helps only in winter, planned at about 5% of the yearly need. It starts in December, January is the worst month, and from the basement its heat warms the floor too.
A battery moves solar power to later hours. A warehouse in Hamme has strong solar but uses most power in the evening. Its three-phase battery system of 30.8 kWh stores the daytime solar.
Weighing solar for your roof as well? Read when business solar panels pay off, and when a battery belongs with them.
Frequently asked questions
Does a heat pump have a big start-up current?
No: modern inverter heat pumps adapt their power, according to Energuide for example from 30% to 100%, and start gently. Your quarter-hour peak comes from long running at full power and from the backup heater, not from the start itself.
Does the capacity tariff also apply in Wallonia and Brussels?
Not in the same way: in Wallonia the standard low-voltage tariff up to 56 kVA has no capacity term. Professional sites with peak metering at ORES pay one on the month's eleventh highest quarter-hour and the annual peak. In Brussels, check your Sibelga invoice; the connection limit applies everywhere.
Can a battery keep the heat pump running in a power cut?
Yes, if the battery system can run as an island (on its own, without the grid) and is sized for the heat pump. Our guide on emergency power for your business compares the options.
Want to know whether your connection can take a heat pump?
We start with your data and your heat pump quote, not with a battery. One of our engineers also checks whether a battery saves you a heavier connection.
- Step 1: Send your data. Send a year of quarter-hour data from Mijn Fluvius, your connection size and the heat pump quote with its maximum electrical input.
- Step 2: Measure if needed. If data is missing, we measure your consumption for a short period first; our monitoring software shows consumption per phase.
- Step 3: Analysis and sizing. We add the heat pump to your winter peak: does it fit, what can control do, what is left for a battery?
- Step 4: Design and installation. Technical design, installation and commissioning.
- Step 5: Follow-up. Monitoring and support in the app and the VRM portal.
Our business battery systems range from small SME installations to modular systems up to 1 MW.
Sources
- NIBE: capacity tariff and heat pumps
- Energuide: are there any disadvantages to a heat pump?
- Energuide: how to limit my heat pump's power consumption?
- Energie+ (UCLouvain): sizing the most common heat pumps
- Vlaamse Nutsregulator: capacity tariff
- Fluvius: frequently asked questions on the capacity tariff
- Fluvius: frequently asked questions on peak metering
- Vlaamse Nutsregulator: low-voltage connection tariffs 2026 (details)
- Inagro: when is a medium voltage cabin worth it?
- ORES: your invoice with peak metering
- CWaPE: low-voltage distribution tariffs in Wallonia in 2026