Eichrecht – Signed Meter Values
This resource is for e-mobility service providers (EMSPs) and EV drivers who wish to see how much electricity was supplied in a particular charge session.
In accordance with the German calibration law (Mess-und Eichrecht), charge point operators may be required to provide signed meter data to EMSPs and drivers, so they can verify these values against the information displayed on the invoice for that charge session.
GreenFlux offer software for Charge Point Operators (CPO) to manage a network of charge stations. In this capacity, we facilitate the exchange of Signed Meter Values through networks and provide instructions to support users in understanding and processing the information provided by CPOs.
Short description
A charge station with a calibrated meter will produce digitally signed (encrypted) meter values. These encrypted meter values cannot be manipulated by a third party. With the help of ‘ Transparency software’ , users can decrypt the meter values and compare them against the values that have been charged to them.
To verify that the right amount of electricity has been charged, users need to know:
- The encrypted data (“signed_data”)
- The decryption key (“public_key”)
- The encryption method (“encoding_method”)
- Where to find and download the transparency software (“url”)
Signed Data file
GreenFlux provides this data a JSON format via URL in the CDRs. Below is an example of a Signed Data for a charging session.
Please note that different manufacturers may apply different formats and do not use all fields.
| Field | Data available | Description |
|---|---|---|
| Session ID | Available | ID of the charging session |
| EVSE_ID | Available | ID of the EVSE (unique Connector of charge station) |
| Encoding Method | Optional | Depending on the manufacturer, the encoding method might differ. More information below |
| Encoding method version | Optional | Version of the Encoding Method |
| Public key | Optional | The key required for decryption. May be part of the message or needs to be looked up elsewhere |
| Nature | Always | Indicates the metervalues for start and end of a charging session |
| Plain data | Optional | The unencrypted metervalues |
| Signed data | Always | The relevant encrypted/signed data |
| URL | Optional | The URL where the decryption software can be downloaded |
How to decrypt
Please follow the URL in the Signed Data File to go to the website of the Transparency Software. Follow the instructions provided by the provider of the software.
Public Key
I n most cases, the “public_key” is not provided through the Signed Data file. The public key then can be retrieved either:
- Checking the public registry in Germany: https://www.bundesnetzagentur.de/DE/Sachgebiete/ElektrizitaetundGas/Unternehmen_Institutionen/E-Mobilitaet/Ladesaeulenkarte/start.html
- Checking on the Charge Station itself for the public key
- Asking the Charge Point Operator if neither of the two options above are available. The Operator and Operator contact details should be part of the transaction details provided by the eMSP.
List of Encoding methods and related Software vendors
Manufacturers may have their own transparency software or use a software implemented by multiple companies.
Below is a list of relevant Encoding Methods known to GreenFlux.
| Encoding method | Software | URL |
|---|---|---|
| Alfen Eichrecht | Alfen Eichrecht encoding / implementation | https://alfen.com/de/downloads |
| OCMF | Proposed by S.A.F.E | https://www.safe-ev.de/de/transparenzsoftware.php |
| EDL40 E-Mobility Extension | Proposed by S.A.F.E | https://www.safe-ev.de/de/transparenzsoftware.php |
| EDL40 Mennekes | Mennekes implementation | https://www.safe-ev.de/de/transparenzsoftware.php |
Please note that GreenFlux is not responsible for the availability and usability of these transparency software suppliers.
For questions, please contact the manufacturer or Charge Point Operator directly.
For questions, please contact the manufacturer or Charge Point Operator directly.
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