Energy transition
Connecting a heat pump electrically: service connection, meter board and § 14a EnWG
A heat pump is not just a heating matter. For it to run efficiently and safely, the service connection, meter board and control system must be right. Here is what to look out for when planning.
TOKSEL Elektrotechnik editorial teamPublished on 4 min read
More and more property owners in and around Cologne are replacing their gas or oil heating with a heat pump. Planning usually focuses on the heating load, installation location and funding. But the electrical side is just as important: a heat pump is a large load that runs continuously – and it must be properly integrated into the existing electrical installation.
How much power does a heat pump need?
The electrical power consumption of a heat pump for a single-family home is typically a few kilowatts. In addition, there is often an electric heating element (Heizstab) for peak loads or hot water, which alone can draw several kilowatts. Together with a wallbox, cooker and instantaneous water heater (Durchlauferhitzer), capacity at the service connection (Hausanschluss) can become tight.
Modern inverter-controlled heat pumps start up smoothly. Older units without starting current limitation, on the other hand, can cause voltage dips – one of the reasons why grid operators want to know about heat pumps.
Registration with the grid operator
Heat pumps must be registered with the responsible grid operator (Netzbetreiber). Depending on the power rating and the grid operator, approval is also required before commissioning. Registration is handled by the electrical contractor (Elektrofachbetrieb) carrying out the work, which is listed in the installer register (Installateurverzeichnis). As part of this, it is also checked whether the service connection and meter board (Zählerplatz) meet the requirements.
§ 14a EnWG: the heat pump as a controllable consumer device
Since 2024, newly connected heat pumps with more than 4.2 kW have been classed as controllable consumer devices (steuerbare Verbrauchseinrichtungen) under § 14a EnWG. If the grid is at risk of overload, the grid operator may temporarily limit their power to no less than 4.2 kW – so the house stays warm. In return, you benefit from reduced grid fees (Netzentgelte):
| Module | What it means | Requirement |
|---|---|---|
| Module 1 | flat-rate reduction of grid fees | no separate meter required |
| Module 2 | percentage reduction of the energy rate (Arbeitspreis) of the grid fees | separate metering point (Zählpunkt) for the heat pump |
| Module 3 | time-variable grid fees (since April 2025) | combination with Module 1 and a smart metering system |
Which module is worthwhile depends on consumption. For Module 2, the meter cabinet (Zählerschrank) needs an additional meter board.
The meter cabinet as a bottleneck
In many existing buildings, the meter cabinet is where things get stuck. A heat pump often requires:
- an additional meter board for a separate tariff or Module 2,
- space for a control box (Steuerbox) and a smart meter gateway,
- a dedicated, adequately sized circuit with suitable overcurrent protection,
- a residual current device (RCD, FI-Schutzschalter) of the type required by the manufacturer.
If the existing meter cabinet does not comply with the current technical connection rules (Technische Anschlussregeln), a new meter cabinet becomes part of the project. Knowing this early on allows you to plan dates and budget realistically.
Combining photovoltaics, storage and a heat pump
A heat pump becomes particularly economical in combination with photovoltaics: via the SG Ready interface or an energy management system, it can run preferentially when the sun is shining – for example to heat the hot water tank. A battery storage system further increases self-consumption. If you are planning a wallbox at the same time, you should consider all loads in a joint concept.
Checklist for electrical planning
- Determine the heat pump's power data, including the heating element
- Check the service connection capacity and existing large loads
- Check the meter cabinet for space and compliance with standards
- Decide on the tariff and module under § 14a EnWG
- Plan the circuit, cable route and protective devices
- Register with the grid operator before installation
- Installation, measurement and test report (Prüfprotokoll)
We handle the electrical integration of heat pumps, photovoltaics and storage systems in Cologne, Hürth and the Rhein-Erft district – find out more under Electrical installation and E-mobility & solar.
Frequently asked questions
Do I need a separate meter for the heat pump?
Not necessarily. A separate meter is needed if you want to use a special heat pump tariff or Module 2 under § 14a EnWG. Without a separate meter, the heat pump runs via the household meter.
Can the grid operator switch off my heating?
No, not completely. Under § 14a EnWG, it may only reduce the power temporarily and to no less than 4.2 kW. Your heat supply remains guaranteed.
Is my service connection sufficient for a heat pump and a wallbox?
That can only be answered on a case-by-case basis. With a load calculation and, if necessary, load management, a solution can often be found without upgrading the service connection.
Related service
Electrical installation
Electrical installation for commercial and residential buildings – new builds and refurbishments, including meter boards and sub-distribution.
This article provides a general overview (as of October 2026) and does not replace an assessment or advice in the individual case. The applicable standards, laws and the requirements of your grid operator are decisive.
