Charge ledger: session traceability on watt.ma

The charge ledger is the bridge between the operational world of charging sessions and the financial world of invoices and payments. Each session generates one or more charge lines in the ledger, and these lines are never modified, even if an invoice is corrected or a refund is processed. This immutability guarantees complete auditability and data reliability for accounting as well as for disputes.

Overview

In the financial backbone of watt.ma, the charge ledger sits right after the session amount calculation and before the customer balance compilation. It keeps all financial mutations related to a session:

Charging session → Meter data → Applicable tariff → Amount calculation
→ Charge ledger → Customer balance → Invoice or receipt → Collection
→ Reconciliation → Revenue share → Partner settlement → Accounting export

A charge is created during amount calculation. It is then referenced by invoices, payments, refunds, and credit notes without ever changing itself.

Event types

Event type	Description
Energy charge	Amount calculated based on kWh consumed and applicable tariff
Connection fee	Fixed fee triggered at session start
Time charge	Amount based on plugging duration, in hours
Idle fee	Occupancy fee for the connector after charging ends
Boost surcharge	Surcharge applied on a fast charging station
Monthly subscription	Fixed monthly subscription attached to the account
Discount	Manual or automatic discount applied to a charge
Tax	VAT 20 % calculated on taxable amounts
Credit	Accounting credit granted to the customer
Adjustment	Manual accounting correction by an administrator
Refund	Partial or full refund of a paid charge
Credit note (avoir)	Cancellation of part or all of an invoice

Some lines like idle fee and boost surcharge depend on site and tariff configuration. See the page Tariffs to configure these options.

Ledger example

Consider session WAT-000183 on charger CP-003 at Green Energy Park:

Session #WAT-000183
Driver: Driver 02 (RFID badge)
Site: Green Energy Park
Charger: CP-003 — Connector 1
Timestamp: 2024-04-15 14:32:07

Energy                  +61.25 MAD
Connection fee           +5.00 MAD
Employee discount       -10.00 MAD
----------------------------------
Charge total             56.25 MAD
VAT 20 %                +11.25 MAD
----------------------------------
Total amount incl. tax   67.50 MAD

This total directly impacts the balance of the company billing account, here Atlas Logistics. Subsequent credit notes and refunds do not modify this line: they create separate correction lines.

References kept per entry

Each ledger line carries the following references, ensuring end-to-end traceability:

Reference	Description
Session	Unique session identifier, for example WAT-000183
Client	Billing account to which the charge is posted
Driver	Badge or user who triggered the session
Site	Charging site concerned
Charger	OCPP charger identifier
Connector	Physical connector number
Tariff	Tariff applied at the time of the session
Timestamp	Date and time of entry creation
Currency	MAD for all transactions

Use cases

Auditability

An accountant or auditor can rebuild the entirety of financial flows from the ledger, without needing access to invoices.

Customer disputes

In case of a dispute over a session, consult the ledger to justify each line: kWh, tariff, discount, fees.

Accounting corrections

An adjustment or credit note is recorded as a new negative line, preserving the original history.

Tax control

Ledger data can be exported to your accounting tool to verify the consistency of declared amounts.

Audit trail

For each entry, watt.ma keeps an audit trail containing:

Attribute	Description
Author	Identifier of the user or system that created the line
Action	Operation type: creation, correction, refund, cancellation
Timestamp	Precise date and time of the operation
Old value	If applicable, previous amount before correction
Reason	Mandatory comment for any manual modification

Direct modification of a ledger entry is impossible. Only the creation of an adjustment or credit note line is allowed. Ledger lines from past sessions are immutable.

Permissions

Action	Admin	Operator	Reader
View ledger	Yes	Yes	Yes
Export ledger	Yes	Yes	No
Create adjustment	Yes	No	No
Create credit note	Yes	No	No
Edit existing line	No	No	No

Session tracking

Find the complete lifecycle of a charging session.

Billing accounts

Link charges to customer accounts.

Billing reports

Move from charges to invoice creation.

Business billing

Understand how charges feed fleet invoices.

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Charge ledger: session traceability on watt.ma

Overview

Event types

Ledger example

References kept per entry

Use cases

Auditability

Customer disputes

Accounting corrections

Tax control

Audit trail

Permissions

See also

Session tracking

Billing accounts

Billing reports

Business billing

​Overview

​Event types

​Ledger example

​References kept per entry

​Use cases

Auditability

Customer disputes

Accounting corrections

Tax control

​Audit trail

​Permissions

​See also

Session tracking

Billing accounts

Billing reports

Business billing

Overview

Event types

Ledger example

References kept per entry

Use cases

Audit trail

Permissions

See also