This article describes how you implement the requirements of § 14a EnWG (grid-oriented control) when installing charging infrastructure with the reev EMS. You will learn which prerequisites apply, how to wire the control signal via the Teltonika Gateway, and how to carry out commissioning.
Purpose and Benefits
The reev EMS enables compliance with the legal requirements of § 14a EnWG for controllable consumption devices. The responsible distribution system operator (DSO) can temporarily reduce charging power via a control signal to prevent grid overload. In return, operators benefit from reduced grid fees.
Tariff Options for Reduced Grid Fees
Operators of charging infrastructure can choose between two modules:
Module 1: A flat-rate discount on the grid fee per connection point. The amount varies depending on the DSO and is typically between €110 and €160 gross per year.
Module 2: A 60% reduction in grid fees per connection point. This option requires the charging infrastructure to be connected via a dedicated, separate electricity meter.
Tip: When planning new charge points, the charge point operator should contact the responsible DSO early on and apply for reduced grid fees. Existing installations can be voluntarily registered to also benefit from the reduced fees.
Legal Context
§ 14a EnWG requires operators of non-public charging infrastructure with a rated power exceeding 4.2 kW per charge point to make their installation accessible for grid-oriented control by the DSO. The regulation has been in effect since 1 January 2024 for all charge points connected to the low-voltage grid. The specific technical requirements are defined by the respective DSO.
Notice: reev does not provide legal advice and is not authorised to issue recommendations for action. Contact your responsible DSO for the applicable requirements in your grid area. Responsibility for correct implementation lies with the system operator and the qualified electrician carrying out the installation.
Prerequisites
The following prerequisites must be met before installation:
Active reev licence for the site.
Installed and configured Teltonika Gateway (recommended: RUT240, RUT241, RUT300 or RUT956) with I/O adapter.
Existing internet connection (LAN or LTE) at the gateway.
Completed registration of the controllable consumption device with the responsible DSO.
Information from the DSO regarding the control approach used (ripple control receiver, Smart Meter Gateway, or other method).
Meter cabinet is prepared for the installation of the ripple control receiver in accordance with the DSO's specifications.
Technical Concept
How the Control Works
The technical method for implementing temporary power reduction is currently not uniformly standardised. Coordination takes place on a case-by-case basis with the responsible DSO.
The reev EMS supports grid-side control via a potential-free relay contact connected to the I/O adapter of the Teltonika Gateway. The gateway forwards the signal to the cloud-based reev EMS. The reev EMS then reduces the charging power of all charge points at the site to the legally required minimum (4.2 kW per charge point) via OCPP.
DSO Control Approaches
The reev EMS is compatible with the following approaches:
Approach 1 – Ripple Control Receiver (RSE): The control signal is transmitted via the power grid or radio network to a ripple control receiver. The relay contact of the RSE is connected to the I/O adapter of the Teltonika Gateway.
Approach 2 – Smart Meter Gateway (SMGW): The control signal is transmitted via an SMGW to a control box. The relay contact of the control box is connected to the I/O adapter of the Teltonika Gateway.
Notice: Check with the DSO which control approach applies in your grid area before starting the installation.
Hardware and Wiring Requirements
Required Components
The following components are needed for a § 14a-compliant installation:
Teltonika Gateway (RUT240/241/300/956) with I/O adapter
Ripple control receiver (RSE) or control box (depending on DSO requirements)
Control cable and wiring materials (cables, terminals)
Tip (grey – callout box): No additional hardware components beyond the RSE or control box are required, provided the Teltonika Gateway with I/O adapter is already installed at the site.
Wiring the Relay Contact
Route the control cable from the relay contact of the control unit (RSE or control box) to the I/O adapter of the Teltonika Gateway. Use the following pin assignment:
Table
Connection | Pin on I/O Adapter | Function |
Relay contact – Wire 1 | Pin 3 | Digital Input |
Relay contact – Wire 2 | Pin 1 | +VDC (Supply voltage) |
Notice: Ensure that the relay contact is potential-free. An incorrect connection can damage the I/O adapter or the gateway.
Step-by-Step Guide: Installation and Commissioning
Follow these steps for installation and commissioning:
Ensure that the Teltonika Gateway is installed, connected to the internet, and registered in the reev EMS.
Prepare the meter cabinet for the installation of the RSE or control box in accordance with the DSO's specifications.
Mount the ripple control receiver (RSE) or control box in accordance with the DSO's specifications.
Route the control cable from the relay contact to the I/O adapter of the gateway.
Connect the potential-free relay contact to the I/O adapter (Pin 3 = Digital Input, Pin 1 = +VDC).
Check the wiring for correct polarity and secure terminal connections.
Test the control signal: Manually trigger the relay and verify that the signal is received in the reev EMS.
Check in the reev Platform under Energy Management -> Live Monitoring whether the charging power is reduced to the minimum as expected.
Post-Commissioning Checklist
After completing the installation, verify the following points:
Gateway is online and connected to the reev EMS.
Relay contact is correctly connected to Pin 3 and Pin 1 of the I/O adapter.
Manual signal test was successful (charging power was reduced).
Live monitoring shows correct status.
Registration with the Distribution System Operator
Registration of the controllable consumption device with the DSO is the responsibility of the system operator. The following steps are typically required:
Registration of the controllable consumption device with the responsible DSO (before or during installation).
Proof of technical controllability (e.g. via the installation protocol).
Confirmation by the DSO and, where applicable, activation of reduced grid fees.
Notice: The exact requirements and forms vary depending on the DSO. Contact the DSO early to avoid delays.
Troubleshooting
Problem | Possible Cause | Solution |
Control signal does not arrive in the reev EMS | Faulty wiring at the I/O adapter | Check the connection at Pin 3 and Pin 1. Ensure that the contact is potential-free. |
Charging power is not reduced | Gateway offline | Check the gateway's internet connection and status in the reev Platform under Energy Management -> Live Monitoring. |
Signal is detected but charge points do not respond | OCPP connection between reev EMS and charge points disrupted | Check whether the charge points are online and correctly set up in the reev EMS. |
Gateway shows no digital input change | Relay defective or incorrectly wired | Test the relay separately and replace it if necessary. |
Tip: For issues with the reev EMS configuration, contact reev Support.
Frequently Asked Questions
Is additional hardware required beyond the Teltonika Gateway?
No. Provided the Teltonika Gateway with I/O adapter is already installed at the site, only the ripple control receiver or the DSO's control box is needed. No further hardware components are required.
To what value is the charging power reduced when a control signal is received?
The reev EMS reduces charging power to a minimum of 4.2 kW per charge point, as required by law.
Can the reev EMS be used for § 14a without a ripple control receiver?
Yes. In addition to the RSE, the reev EMS also supports control via a Smart Meter Gateway (SMGW) with a control box. The potential-free contact is connected to the Teltonika Gateway in the same way in both cases.
What happens if the gateway's internet connection is interrupted?
The reev EMS sets fallback values (Smart Charging Profile) at the charge points via OCPP. In an offline scenario, vehicles charge at a safe, pre-set maximum value.
Does the system operator need to register the installation with the DSO?
Yes. Registration of the controllable consumption device with the DSO is mandatory and is the responsibility of the system operator.
Which Teltonika models are compatible?
The recommended and tested models are the RUT240, RUT241, RUT300, and RUT956. In principle, all Teltonika RUT models are compatible with the reev EMS.