The e-Mobility Eco-system
The EV charging market consists of several interconnected actors:

In a typical charging session, the driver starts a session through an eMSP or pays directly. The CPO’s platform authorizes and controls the charger. Charging and cost information is then exchanged between the CPO, eMSP, roaming provider, and payment provider. At the same time, smart charging can adjust the electricity demand to reduce costs and support the grid.
The GreenFlux platform builds features for 2 of these actors, the CPO and the eMSP:
- CPO: Charge Point Operator. Operates, maintains and sometimes owns the infrastructure and/or land.
- eMSP: e-Mobility Service Provider. Provides services to drivers, like access to charge stations and monthly invoicing, as well as management services for fleets.
e-Mobility Transactions
EV drivers can access and pay for charging sessions in three ways:

1. Ad Hoc charging
In an ad-hoc transaction, the EV driver charges without registration or a prior subscription and buys the charging service directly from the CPO. Payment is made at the charging station.
GreenFlux supports several ad-hoc charging channels:
- Charge Assist or a white-label app/web app: The driver starts the session and supplies a payment method through an app or browser.
- CPO-owned app using the Charge Assist API: The CPO controls the customer facing experience and its payment integration.
- Payment terminal integration: The driver pays by card or contactless method through a supported terminal setup.
Note: This process can also be initiated by scanning a QR code displayed on the charger.
A Payment Service Provider (PSP) is normally required to authorize and process the payment.

Note: The PSP typically charges a fee per transaction. The CPO may choose to absorb this cost or pass it on to the EV driver.
2. CPO Subscription
In a CPO Subscription transaction, the EV driver establishes a direct commercial relationship with the Charge Point Operator (CPO).
- This gives the driver access to the CPO’s charging infrastructure.
- The agreement may include subscription benefits such as discounted tariffs or bundled charging packages (e.g., 10 EUR/month subscription for reduced kWh rates).
- In some cases, the CPO may also operate as an eMSP, but the relationship is still directly between the driver and the CPO.
In a CPO subscription transaction, the driver has a direct commercial relationship with the CPO and charges under a subscription, membership, or preferential pricing arrangement. The CPO operates or manages the charging service. No roaming intermediary is part of the commercial relationship between the driver and CPO.

3. eMSP subscription (Roaming)
In a Roaming transaction, the EV driver does not have a direct commercial relationship with the CPO. Instead, they contract with an e-Mobility Service Provider (eMSP), who then manages the commercial and technical connection with one or more CPOs.
- The driver pays the eMSP (retail transaction).
- The eMSP pays the CPO(s) (wholesale transaction).
- Depending on the roaming setup, an additional roaming platform may be involved (e.g., GreenFlux).

3.1. Roaming Models
- GreenFlux Managed Roaming:
- Driver → eMSP (retail transaction).
- eMSP → GreenFlux (roaming provider) (B2B).
- GreenFlux (roaming provider) → CPO (B2B).

- Self-managed Roaming (direct eMSP–CPO relationship):
- Driver → eMSP (retail transaction).
- eMSP → CPO (wholesale transaction).

3.2. Roaming payment flow for self-managed roaming

4. Fleet reimbursement transaction
In addition to Ad-hoc, CPO Subscription, and Roaming, there is a fourth type of transaction, specific to CPOs: Reimbursement.

4.1. Primary Use Cases
- Business Location Charger:
- The CPO operates a charger at a company site.
- The CPO charges drivers/eMSPs at rate X cents/kWh, and reimburses the landlord (energy contract holder) Y cents/kWh for the electricity.
- Home Charger for Fleet Drivers:
- The CPO installs and manages home chargers for fleet drivers.
- The driver charges at home; the CPO collects charging data (CDRs) and invoices the fleet manager.
- The fleet manager reimburses the employee (e.g., Y cents/kWh) for electricity costs, typically as part of payroll.
4.2. Fleet Reimbursement Flow

- Driver initiates a charging session (at home or workplace).
- CPO records charging data (CDRs) and applies reimbursement tariff.
- Fleet owner (or employer) reimburses the driver for the electricity consumed or CPO reimburses the energy contract holder (e.g., landlord or utility).
GreenFlux Billing (Tariff) Engines
GreenFlux platform is equipped with 3 billing engines, which aim at calculating costs for a wide range of use cases. These billing engines run every time we calculate a CDR and are responsible for calculating the wholesale costs and/or reimbursement costs and/or retail costs, as applicable.

Check Understanding tariffs and pricing in the GreenFlux platform: CPO and eMSP perspectives to know how to model your tariffs and prices, whether you are a CPO or and EMSP
For each billing engine above, there is a dedicated article explaining in detail how it works:
