Section 14a EnWG: controllable devices and network charges

A heat pump fitted in Germany today comes with a condition: on a day when the local low-voltage network is overloaded, the distribution system operator (DSO) can turn it down. In return, the network charge is reduced; whether the owner receives that reduction depends on the electricity supply contract.

The legal basis is Section 14a of the Energy Industry Act (Energiewirtschaftsgesetz, EnWG). The Bundesnetzagentur set the detail in two determinations. BK6-22-300 covers control. BK8-22/010-A covers network charges.

What Section 14a does

The DSO may reduce the grid import of controllable devices when a current or voltage problem threatens its low-voltage network. The DSO must base that decision on a network-state assessment. BK6-22-300 presumes the assessment is adequate when it uses minute-resolution data from at least 15% of the connections in the area, or from at least 7% plus the transformer feeders.

In exchange, the DSO may not refuse or delay the connection of a covered device because of limited network capacity. Control is a temporary congestion tool. The duty to reinforce the network stays with the DSO.

The limit applies to import from the public network only. The DSO cannot limit household loads that are not covered, and cannot require a PV system or battery to export.

Devices in scope

A device is in scope when all four conditions apply:

1. It is connected directly or indirectly at low voltage (network level 6 or 7).
2. Its network connection rating is more than 4.2 kW. A device rated exactly 4.2 kW is out of scope.
3. It is in a covered category.
4. It was commissioned on or after 1 January 2024, or its operator has moved it into the new regime.

The covered categories are:

• EV charging points that are not publicly accessible;
• heat pumps, including their auxiliary or emergency heaters;
• space-cooling equipment;
• battery storage, for its import from the grid. A battery that can technically charge from the grid is in scope even if it is set to charge from PV only.

A 3.7 kW single-phase wallbox (16 A) is out of scope. An 11 kW three-phase wallbox (16 A per phase) is in scope.

Heat pumps and cooling units are grouped by operator. If several heat pumps of the same operator sit behind one connection, their ratings are added. When the sum is more than 4.2 kW, the group counts as one controllable device. Cooling units are grouped the same way, as a separate category. Devices belonging to different operators do not have to be grouped. Two 3 kW heat pumps of one operator therefore form one 6 kW device. Wallboxes are not grouped. Independently operable batteries are not grouped either; batteries that can operate only together count as one storage installation, whose combined connection rating can bring it into scope.

Some installations are exempt from participation:

• charging points used by emergency services with special rights under Section 35 StVO;
• heat pumps and cooling that do not heat or cool living, office or other occupied rooms, for example process cooling or equipment for critical infrastructure;
• devices that demonstrably cannot be controlled, and cannot be made controllable at reasonable cost, if they are commissioned by 31 December 2026.

The second exemption matters for commercial and industrial sites. A chiller for a production process is outside Section 14a. A heat pump that heats the office on the same site is inside it.

Existing installations

Devices commissioned before 1 January 2024 follow the transitional rules in both determinations:

• With a reduced network charge under the old Section 14a, the old arrangement continues until 31 December 2028. From 1 January 2029 a covered device moves into the new regime. An operator can move earlier. That move cannot be reversed.
• For night-storage heaters with the old reduced charge, the old arrangement continues while the heater operates unchanged. Night-storage heaters do not enter the new regime.
• For other device types with the old reduced charge, the old arrangement ends on 31 December 2028. They cannot join the new regime.
• Without a reduced network charge, the new rules do not apply. The operator can opt in, and that choice also cannot be reversed.

A substantial change to an existing device can make it a new installation. The Bundesnetzagentur treats a change as substantial when the device's performance changes significantly or its purpose changes. A replacement heat pump is normally treated as a new installation.

Minimum power during control

The operator decides, per device, between two control methods:

• Direct control: the DSO sends a maximum-import setpoint to one device.
• Control through an energy-management system (EMS): the DSO sends one setpoint for all devices connected to the EMS. The EMS divides that power among them as the operator chooses.

In both cases the setpoint is a ceiling. The device can use less.

With direct control the minimum is 4.2 kW per device. For a heat pump or cooling device (or group) rated above 11 kW, the minimum is 0.4 × the rating.

With EMS control the minimum is:

Pmin = 4.2 kW + (n − 1) × GZF × 4.2 kW

Here n is the number of controllable devices on the EMS and GZF is the simultaneity factor. If a heat pump or cooling device above 11 kW is on the EMS, the first term changes. It becomes the larger of 0.4 × the summed heat-pump rating and 0.4 × the summed cooling rating.

The EMS limit applies to grid import. PV generation and battery discharge behind the connection are not limited. During an event the heat pump in the third example can draw 7 kW from the grid while the wallbox charges from PV.

If a device cannot reduce exactly to the setpoint, it must go to the next lower power it can reach. For a fixed-speed compressor that cannot run at 4.2 kW, the next lower value can be off.

If a Section 14a limit conflicts with another control signal, such as a dynamic tariff or a virtual power plant dispatch, the Section 14a limit wins. The operator must make sure the equipment enforces that priority.

Duration and preventive control

Control lasts only while the network problem exists. The DSO must trigger control through the metering point operator without delay after its network-state assessment. BK6-22-300 presumes that five minutes meets this. The device must apply the command without delay. When the event ends, the DSO must restore power in steps, so that the returning load does not cause a new overload.

A DSO that cannot yet assess its network state from measurements may use preventive control, based on planning data. Preventive control is limited to two hours a day. In each network area it can run for 24 months from its first use there, and it must end by 31 December 2028 at the latest. The minimum power still applies. These limits apply only to preventive control. State-based control has no fixed daily maximum.

Network-charge modules

The reduction applies to the network charge, not to the supplier's energy price. The supplier must show the Module 1 reduction as a separate item on the bill. That disclosure does not itself require the supplier to pass the reduction on to the final customer under every existing supply contract.

Module 1: flat annual reduction

Module 1 is the default. The annual reduction is:

reduction = EUR 80 + 3,750 kWh × low-voltage energy charge × 0.2

The EUR 80 is based on the operator's share of the price caps for the smart meter (EUR 50) and the control box (EUR 30). The second term is the "stability bonus". It uses an average device consumption of 3,750 kWh a year. At a network energy charge of 8 ct/kWh gross, the reduction is 80 + 60 = EUR 140 a year. The Bundesnetzagentur quotes a range of about EUR 110 to 190, depending on the network area.

Module 1 is granted per market location, not per device. It needs no separate meter. It cannot reduce the network charge at the market location below zero.

Module 2: 40% energy charge on a separate meter

Module 2 reduces the network energy charge to 40% of the DSO's normal low-voltage rate. The DSO does not charge a base price at that market location. The device must be metered separately and billed at its own market location without registered load measurement. The operator must choose Module 2 explicitly.

Only Module 2 needs a separate meter. Under Modules 1 and 3 the device can use the household meter.

Module 3: time-variable network charge

Since 1 April 2025, an operator on Module 1 can add Module 3. It needs an intelligent metering system (a smart meter with a Smart Meter Gateway) and cannot be combined with Module 2. It applies to all consumption at the market location.

Module 3 has three price levels:

• High (HT): at least two hours a day, at no more than twice the standard rate.
• Standard (ST): the normal energy charge.
• Low (NT): between 10% and 40% of the standard rate.

The DSO applies HT and NT in at least two quarters of the year. The standard rate applies at all other times. The DSO publishes the quarters, time windows and prices on its price sheet in the year before. The levels are set so that a household with the standard H0 load profile pays the same as without Module 3. Module 3 therefore saves money only if load moves into the low windows.

Choosing a module

Compare Module 1 with the Module 2 saving:

• Module 1: 80 + 750 × energy charge (EUR/kWh).
• Module 2: 0.6 × annual device consumption × energy charge, plus the base price avoided, less the annual cost of the second metering point.

Registration and the control chain

Under Section 19(2) NAV, the operator must notify the DSO before a controllable device is commissioned. The operator must also report planned power changes and permanent decommissioning in advance. At registration the operator chooses direct or EMS control for each device.

Section 14a(4) EnWG requires control through the Smart Meter Gateway once the metering point has an intelligent metering system. A metering point operator using the agile rollout can defer that until the gateway's application update.

In the regulated chain, the metering point operator installs the Smart Meter Gateway and an FNN control box (Steuerbox) and connects them. The installer prepares the cable from the control box to the handover point. The handover point is one of two interfaces. The e-netz Südhessen TMA, a typical example, specifies them as follows:

• Digital: an RJ45 socket with at least Cat 5 cable to the device or EMS. The device or EMS must implement VDE-AR-E 2829-6-1. The Bundesnetzagentur recommends EEBUS as the minimum industry standard.
• Analogue: a six-terminal control-signal strip. One terminal carries the switched signal for the controllable device. Three others carry the 60%, 30% and 0% feed-in signals for generation. The control box drives these through volt-free normally-open contacts rated 5 to 250 V and 1 A.

A contact has two states, so an analogue interface switches the device between unrestricted operation and its minimum power. EEBUS carries a setpoint in watts. With direct control of several devices, each device needs its own interface, so the installer adds coupling relays or a network switch. This is why DSOs recommend an EMS on sites with several devices.

In that TMA, the Smart Meter Gateway and control box are supplied from the unmetered side. The terminal strip and any coupling relays are supplied from the metered side.

Failure modes

The DSO must document every control event: the network-state assessment, the devices addressed, the depth and the duration. The operator must be able to show, case by case, that each reduction was carried out. Both keep these records for at least two years. The Bundesnetzagentur can request them, and the DSO can request the operator's record if it has justified doubt. Test for these five faults:

1. Inverted or miswired contact. The device is limited all the time. A wallbox sits at 6 A per phase on every charge. A 60 kWh car battery then takes about 14 hours to fill instead of about 5.
2. Lost communication on EEBUS. Under the EEBUS Limitation of Power Consumption use case, a device that receives no heartbeat from the control box for 120 seconds goes to its failsafe limit. It stays there for at least the failsafe minimum duration, which is 2 to 24 hours. A weak LTE signal at the meter cabinet can therefore limit a heat pump for hours when the DSO has sent no command.
3. Command received, not applied. The contact operates or the EEBUS limit arrives, but the wallbox configuration ignores the input. The installation is non-compliant, and nothing on the DSO side shows it.
4. Competing control signal. A tariff optimiser or aggregator dispatch raises the load during an event. BK6-22-300 requires the Section 14a limit to take priority.
5. Measurement at the wrong point. Under EMS control, a submeter on the heat pump reads 7 kW during an event. That is above 4.2 kW but inside the 10.5 kW limit for the group. Under direct control, a submeter reads 5 kW on a wallbox circuit because it also measures a garage socket. Neither reading shows non-compliance. The limit applies to the grid import of the controllable devices only.

Test the chain at commissioning. Ask the metering point operator for a test command. Check that the device power falls to the expected value and returns afterwards. Ask how the control box behaves when its link fails, and record the failsafe limit and duration configured in the device.

DSOs also publish monthly data for each network area where control took place. The data includes the number of devices controlled, the average power curtailed and the total duration, by transformer-station postcode, by the 15th of the following month. If your circuit data shows a limit in a month with no published event for your area, look for faults 1 or 2.

Measuring a control event

The DSO's control record shows the command. The billing meter settles the network charge. Neither shows how the device itself responded. A circuit measurement fills that gap. EpiSensor products provide operational monitoring beside a Section 14a installation. The certified Smart Meter Gateway, the control box and the billing meter come from the metering point operator and the DSO, and eligibility for a network-charge module is decided there.

A ZEM electricity monitor on the wallbox or heat-pump circuit measures current, voltage and power on each phase. It reports through the Zigbee mesh to the ZGW-20 Gateway, with timestamps at 1 s resolution. If the radio link drops, the ZEM holds up to 70,000 readings in flash. A dimming event appears as a step: an 11 kW wallbox falls from 16 A to 6 A per phase and returns when the event ends. Edge stores the data locally and can export it to the operator's EMS or platform over MQTT or HTTPS.

For an analogue interface, the command can be logged too. Ask the installer to fit a coupling relay on the customer side, as the TMA already allows. A ZDI digital-input model in the ZPC pulse counter family on a volt-free contact of that relay reports the open or closed state. Do not connect monitoring equipment directly to the metering point operator's control box. With EEBUS, the EMS or device logs the setpoint, and the ZEM shows the response.

BK6-22-300 does not prescribe the form of the operator's case-by-case record. The command log and the circuit data together are a practical way to provide it. They do not replace the billing meter for Module 2 settlement, and a ZEM is not a control box, Smart Meter Gateway or EEBUS control device.

The EV charging load-management guide and the heat-pump performance-monitoring guide show how to lay out that measurement.