Eichrecht Implementation - Deep dive into German Measurement and Calibration Law

Are you a beginner looking to get some basic idea of what Eichrecht is all about? Then, I would strongly advise you to first read my another post Simplified guide to Eichrecht conformity I German calibration law for electric vehicle charging. This post may further elaborate to those who have some basic idea and looking to start implementation.

Basic of Eichrecht Calibration Law:

The Basic principle of Eichrecht is the verifiable accuracy of measured values. , ensuring that the customer pays only for what they receive.

Accordingly, the German Measurement and Calibration Law (MessEG) and the Measurement and Calibration Act (MessEV) require that the measured values be determined by a calibrated measuring device and that data records be kept in a secure and verifiable manner.

However, the law fails to offer any implementation recommendations on the procedure/ instrument to validate the data.  As a result, 3 different approaches available in the market:

■ S.A.F.E initiative – a workflow that allows the customer to verify meter values independent via Transparency software 

■ SAM (Storage and Display Modules) – a memory and display module installed in the charging station., where no online verification possible.

■ The ”Innogy” Solution – a complete system certification with a mobile application.

Here in this post, we shall further deep-dive into Eichrecht implementation - according to S.A.F.E initiative workflow .

Overview of S.A.F.E Eichrecht- process flow

Below picture may give an overview of how the whole Eichrecht process from EV driver starting a charging session by authenticating via RFID/app to encryption and decryption of charging data (meter values). 

What are the obligations for an Eichrecht compliant charging station hardware (manufacturer)

Requirements for EV charging stations supplier shall be written in multiple pages, as the implementation still vary a lot from one manufacturer to the other; and one encryption scheme to the other. But the below basic obligations shall be necessary irrespective of any type of implementation.

1. A charging station must contain a calibrated meter /module (”Messkapsel” in German) that creates digital signature(s) for the charging session. 

2. A digital signature is created with a private key as part of a private/public key pair. The private key must be stored safely on the charging station and never be separated from the hardware component (e.g. the meter) that creates the signature.

3. The public key is used to verify the digital signature’s authenticity and integrity. It must be displayed on site so that the end customer can photograph it or write it down. 

4. The display of the electricity meter value within the charging station.

5. Display the calibration certificate of meter/capsule to customer (shall be via website, downloadable)

What are the obligations for an Eichrecht compliant charge point operator (CPO)

The digital signature must be securely stored in the CPO backend and sent to the corresponding EMSP together with a charge detail record. The CPO is also obliged to store these measured values permanently and make them available to the EMSP upon request.

If the charging station is located in public areas or has a maximum capacity greater than 3.7 kW, the CPO must report the station to the German regulatory agency called the Bundesnetzagentur (BNetzA). In this case, the CPO must also publish the meter or measuring capsule’s public key to a database operated by the BNetzA using a downloadable form. The BNetzA public registry is also available here.

What are the obligations for an Eichrecht compliant E-Mobility Service Provider (EMSP)

In conformity with calibration law, an invoice for a charging session must include the following pieces of information for each charging session:

1. Start date and time and end date and time or duration of charging process
2. Unique transaction identifier
3. Identification token that the end customer(s) used to authenticate and authorize themselves
at the station (e.g. an EMAID14)
4. Identification of the charge point
5. Tariff applied
6. Costs associated with the charging session
7. Start and end meter reading in kWh, if billed based on kWh
8. Measurement result (kWh & If the charging process duration is included in the calculation, this must also be
indicated on the invoice with start and end time).
9. Reference on how to check the measured values for accuracy. Currently, calibration authorities have declared two possible alternatives that both comply with calibration law:

• Local storage of measured values : The invoice must contain a note saying ”Local storage; measured value check must be performed on site.”
• Digital signature procedure with transparency software : The invoice must contain a note stating ”Measured value with digital signature” plus approved version of the transparency software, as well as a note explaining how to access the digital signature and transparency software – for example: via a specific download link.

Note: This is regulated in document 6-A published by PTB. The document is titled ”Regeln und Erkenntnisse des Regelermittlungsausschusses nach § 46 des Mess- und Eichgesetzes für Messgeräte und Zusatzeinrichtungen im Anwendungsbereich der E-Mobilität”.

How does an Eichrecht compliant Invoice look?

This has·to·be article (link) offers an illustration of invoices that conform to calibration law.

Hope this post has given you an overview (if not, triggered some questions at least), feel free to shot them. Having said that implementation details explained above are only an indication; in fact every CPO is free to carry out a separate conformity assessment by a conformity-assessment body such as PTB or VDE Testing Institute. These organizations also have an advisory function and can help design specific charging station solutions.