Why must the kilowatt-hours be measured to legal standards?
The session record shows 38.20 kWh. A driver wonders: who guarantees that number?
Inside the charger, a meter measured it, and signed the readings at start and end.
The questionWhy can a driver trust the kWh on the invoice?
base maximum permissible error
base maximum permissible error
base maximum permissible error
10 October 2028, no retrofitting; national-rule equipment until April 2030
Accuracy determined at the transfer point to the car, as AC or DC energy.
From national to European
The kWh are what drivers pay for, so their measurement falls under measuring law. Directive (EU) 2026/706 adds measuring systems for charging equipment to the EU Measuring Instruments Directive: manufacturers state an accuracy class, the accuracy is determined where the energy passes to the car, and the result may be shown on the charger, remotely or on the driver's own device. Member States apply the new rules from 10 October 2028, without retrofitting existing charge points; equipment that meets national rules and was placed on the market before 10 April 2030 may still be put into use.
Readings that travel with the invoice
Where national law asks for it, as in Germany, the meter signs its readings. carries the signed start and end values from the charger to the backend, and the meter's public key lets drivers and operators check that they are genuine. in can carry this signed data on to the provider.
The meter inside the charger is described in Charging hardware, stop 07.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
Where is the accuracy of a charging meter determined under the 2026 rules?
The energy that counts is what passes to the car, so accuracy is determined there.
Do existing charge points have to be retrofitted for the 2026 rules?
The new requirements apply without retrofitting obligations for existing charging stations.
What lets a driver check that signed readings are genuine?
Signed readings can be verified with the public key of the meter that signed them.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. EV charging fundamentals, stop 03 Glossary
- OCPI Open Charge Point Interface: an open protocol for roaming between operators and e-mobility service providers. EV charging fundamentals, stop 03 Glossary
- CDR Charge detail record: the digital receipt of a session, with energy, duration and tariff. EV charging fundamentals, stop 05 Glossary
- EUR-Lex: Directive (EU) 2026/706 amending Directive 2014/32/EU, Annex Va (MI-011). https://eur-lex.europa.eu/eli/dir/2026/706/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- EUR-Lex: Directive (EU) 2026/706 amending Directive 2014/32/EU, Annex Va (MI-011). https://eur-lex.europa.eu/eli/dir/2026/706/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- EUR-Lex: Directive (EU) 2026/706 amending Directive 2014/32/EU, Annex Va (MI-011). https://eur-lex.europa.eu/eli/dir/2026/706/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- Open Charge Alliance: Signed Meter Values (Eichrecht paper), version 1.0, February 2025. https://openchargealliance.org/wp-content/uploads/2025/05/signed_meter_values-v10-1.pdf. Checked 09 Oct 2026. Licence: CC BY-ND 4.0.
- EVRoaming Foundation: OCPI 2.3.0, CDRs module: credit CDRs, push and pull model. https://github.com/ocpi/ocpi/blob/2.3.0/release/core/mod_cdrs.asciidoc. Checked 09 Oct 2026.