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§ 14a EnWG & SteuVE

Current Development

The implementation of § 14a EnWG is still being rolled out. Control boxes and Smart Meter Gateways are currently being deployed.

evcc supports external control of charging points by grid operators in accordance with § 14a EnWG. This enables reduced grid fees whilst ensuring grid stability.

Background​

§ 14a of the German Energy Industry Act (EnWG) regulates grid-friendly control of controllable consumption devices (SteuVE). Grid operators can temporarily reduce the power of large consumers such as wallboxes, heat pumps or battery storage systems in the event of grid overload. In return, customers receive reduced grid fees.

Important points:

  • Affects consumers from 4.2 kW power
  • Control via Smart Meter Gateway and control box
  • Customers benefit from reduced grid fees

evcc supports two connection methods: Relay (analogue via a switch contact) or EEBus (digital via the EEBus protocol).

Setup​

§ 14a EnWG control uses evcc's Load Management. When setting up HEMS, an internal lpc (Local Power Control) control circuit is automatically created, to which all charging points and other consumers are assigned. When a reduction signal is active, evcc sets a temporary power limit for this circuit.

No separate load management configuration is required. If you already use load management, the lpc control circuit will be placed as the highest level above your existing circuits.

tip

HEMS can also be set up via the configuration interface.

Configuration via Relay (Analogue)​

The analogue connection via a switch contact is the simplest solution. The control box activates a contact which is evaluated by evcc.

Basic Configuration​

hems:
  type: relay
  maxPower: 8400 # Total power limit when signal is active (in watts)
  limit:
    # Plugin-specific configuration

Determining the Power Limit​

The power limit is communicated to you by the grid operator. For multiple controllable consumption devices (SteuVE), the simultaneity factor is taken into account. You can also calculate the limit yourself using the formula: Total limit = Number of SteuVE × 4.2 kW × Simultaneity factor. Details on the calculation can be found here.

Examples for Different Connections​

When using a Raspberry Pi, the GPIO pin can be read directly:

hems:
  type: relay
  maxPower: 8400 # Example for 2 SteuVE
  limit:
    source: script
    cmd: gpioget gpiochip0 17 # Read GPIO pin 17
    # Return value: 0 = not limited, 1 = limited

Configuration via EEBus (Digital)​

The digital connection via EEBus is the future-proof and preferred solution. The control box communicates directly with evcc via the EEBus protocol and automatically transmits the power limit.

Prerequisites​

  • evcc installation with EEBus support
  • Control box with EEBus interface
  • Network connection between evcc and control box

Step 1: Generate Certificates​

EEBus requires certificates for secure communication. These must be created once. Run the following command in the console:

evcc eebus-cert

This command creates the required certificates and displays the configuration that must be inserted into evcc.yaml.

Step 2: Basic EEBus Configuration​

Add the EEBus configuration to evcc.yaml:

# Basic EEBus configuration
eebus:
  certificate:
    public: |
      -----BEGIN CERTIFICATE-----
      # Insert public key here
      -----END CERTIFICATE-----
    private: |
      -----BEGIN EC PRIVATE KEY-----
      # Insert private key here
      -----END EC PRIVATE KEY-----
  # Optional: Specify network interface (recommended)
  interfaces:
    - eth0 # or the appropriate interface
  # Optional: Define your own SKI
  shipid: EVCC-1234567890abcdef

Step 3: HEMS Configuration​

Configure the HEMS interface for § 14a EnWG:

hems:
  type: eebus
  ski: "1234-5678-90AB-CDEF" # SKI of the control box
  # You can find the SKI in your control box documentation
Note

With EEBus, the power limit is automatically transmitted by the control box.

Step 4: Determine SKI and Pairing​

Determine evcc SKI​

After starting evcc, your own SKI is displayed in the logs:

evcc --log debug | grep -i ski

Perform Pairing​

  1. In the control box: Add evcc as HEMS

    • Enter the SKI of evcc
    • Specify the IP address of evcc
    • Start the pairing process

  2. In evcc: Add the control box SKI to the HEMS configuration

    • Enter the control box SKI in the HEMS configuration
    • Restart evcc

  3. Check connection:

    # Activate trace logging for EEBus
    evcc -l trace eebus
Important
  • Certificates only need to be generated once
  • After successful pairing, the configuration must not be changed

How It Works​

Normal Operation​

In normal operation, evcc charges without power limitation by the HEMS. The charging points operate with their normal configuration and are coordinated by additional Load Management restrictions if applicable.

Reduction Signal Active​

When the grid operator sends a reduction signal:

  1. Relay: The contact is closed, evcc activates the configured maxPower limit
  2. EEBus: The control box digitally transmits the calculated total limit

evcc reduces all charging points assigned to the lpc circuit according to the limit. If total consumption is too high, charging processes can also be stopped. The control affects all modes (Solar, Min+Solar, Fast).

Battery control during reduction: If active battery control is configured and grid charging of the home battery is active, this is automatically paused. The battery is set to "hold" mode so that it neither charges nor discharges. After the power reduction ends, grid charging automatically resumes.

When a control limit is active, a banner with control notice is displayed on the main page in evcc.

Controlling Additional Consumers​

In addition to charging points, other controllable consumers can also be integrated into § 14a load management. This applies e.g. to heat pumps or battery storage systems that are connected via EEBus or configured as meters with an additional relay output.

The control takes into account the current power consumption of all consumers assigned to the internal lpc circuit. This automatically includes all charging points and all meters with corresponding switching outputs or EEBus interface with LPC use case as other consumers.

First, all other consumers are dimmed. The remaining power is then distributed to the active charging points. Due to flat dimming of other consumers, the available charging power for active charging points can in exceptional cases even be higher than in normal state. If throttling the charging points including dimming all other consumers is not sufficient, charging processes at charging points are interrupted.

Availability

Currently, only one dimmable meter (EEBus consumer) exists. This feature is being expanded and compatible meters will be marked in the device documentation.

Further Information​