Billing & metrology law

Who charged, and what it cost — with the proof to go with it

The moment the cars stop belonging to one person, a kilowatt-hour becomes a receivable: it has to be measured, attributed, invoiced and still provable years later. Those four steps run without anyone touching them.

Request a consultation Who bills whom?

From the kilowatt-hour to the invoice

The chain has four links and only one of them lives in software. Measuring and signing happen in the charge point; the backend receives the finished record, attributes it, bills it and keeps it. Knowing the order also explains why billability is decided by the hardware, not by the provider.

Measure

The station's calibrated metering capsule counts what actually flowed — regardless of what the vehicle reports.

Sign

Start and end readings are signed together with timestamps and session identity, in OCMF format. After that the figure cannot be altered.

Attribute

The backend attaches the record to the access medium that started the session — card, app or ad-hoc access.

Bill

Apply the tariff, produce the invoice, collect, archive the receipt. From here on it is bookkeeping, not metrology.

Metrology law

Why metrology compliance is not a badge

It is an obligation. Anyone selling energy by quantity falls under German metrology law — charging current no differently from a fuel pump. The customer must be able to verify the bill without taking your word for it, and the authority must be able to check it without relying on your systems.

Measure under calibration

The station's metering capsule must be approved for the purpose and validly calibrated. That is a property of the hardware; no software can retrofit it.

Transmit unaltered

Between measurement and invoice nobody may be able to touch the figure, ourselves included — so the signed record is passed on rather than recomputed.

Deliver checkable

The signed record belongs with the receipt. The customer can verify it with freely available transparency software against the station's public key.

Retain

Records must stay available for years, even after the station has been replaced, the tariff changed or the user deleted — so archiving hangs off the session, not the device.

What follows for your specific site — which device, which evidence, which documents the responsible authority wants to see — depends on the installation. We settle that in the project, not on a website.

Constellations

Who is actually billing whom?

Four cases that measure the same thing technically and have nothing in common commercially. Most sites run two of them at once.

Employer and employees

Three pots that must stay apart: private, business and guest charging. Every session is unambiguously attributed by access medium — even when the same person uses the same wallbox for different purposes.

Owners' association and parties

The connection belongs to everyone, the session to one party. Each party gets its own bill and the association gets no lump item to divide by hand.

Operator and drivers

Here the people paying have no contract with you: ad-hoc charging by QR code, card payment, and roaming over OICP and OCPI so other providers' cards work at your sites.

Fleet and cost centre

Not every settlement ends in an invoice. Often it only has to land on the right vehicle, cost centre or project — an export into accounting rather than a receivable.

Employer and employee

Wallbox, employees, and the settlement in between

Few cases are as common, or as often solved by hand, as this one: a company car charges sometimes at the office, sometimes in a home garage, occasionally on the road. Three places, three payers, one vehicle.

At the company car park

The employer pays. Sessions are still recorded per user: company cars, employees' private cars and guests each have their own rules and tariffs.

At the home wallbox

The household pays; the employer reimburses the business share. The home wallbox is connected and business sessions are recorded separately by access medium.

On the road

Third-party points run on the charge card and arrive in the same statement through roaming — otherwise exactly the part nobody enters by hand is missing.

At the end of the month there is a statement per vehicle and per person: how many kilowatt-hours were charged where, which of them were business, and what is to be reimbursed. What follows for payroll tax is your accountants' call; our job is that the figures behind it are sound rather than estimated.

In operation

What then happens by itself

Meter values: compliant, OCMF-signed
Attribution: per access medium
Tariffs: per user group, site, time window
Invoicing: automatic, under your own brand
Collection: SEPA direct debit and card
Ad-hoc: QR code, no registration
Roaming: OICP 2.3 · OCPI 2.2.1
Export: per cost centre and vehicle
Archive: receipt with the signed record

Depending on where it is stuck

Hardware

Can my charge point do this?

The compatibility list — billability is decided by the device.

Fundamentals

What a CPMS is

Billing is one of four jobs. Here are the other three.

Product

aCharge Cloud

What it costs, per charge point per month.

Frequently asked

Billing charging sessions — answered briefly

When does charging have to be billed under metrology law?

As soon as a price is charged and the energy delivered is the basis for it — public or private makes no difference. A flat monthly fee that ignores consumption is a different case, as is charging that nobody pays for.

What is OCMF?

The Open Charge Metering Format: start reading, end reading, timestamps and session identity signed together inside the charge point's metering capsule — not in the backend. That is what makes the figure on the invoice checkable afterwards.

Can employees charge at home and settle with their employer?

Yes — the usual company-car case. The home wallbox is connected, company-car sessions are recorded separately from private consumption by access medium, and handed to the employer as a monthly statement.

How is the money actually collected?

Either by you or by the platform. aCharge Cloud produces the invoices and can collect by SEPA direct debit; publicly accessible sites add card payment and ad-hoc charging by QR code.

What happens to a session while the backend is unreachable?

It is billed in full anyway. The station buffers meter values locally and transmits them once the connection returns; the signature was applied long before that.

Is the meter already built into the wallbox enough?

That depends on the device, not the software. Billing by quantity needs a station with a calibrated metering capsule that can emit signed records; a simple display meter is not enough.