Interoperability networks are ecosystems that allow EV drivers to use charging stations across different operators with a consistent access and billing experience. They connect charge point operators (CPOs), e-mobility service providers (eMSPs), roaming hubs, and backend systems so charging sessions can be authorized, priced, and settled across networks.
What Are Interoperability Networks?
In practice, an interoperability network enables:
– One driver credential (app/RFID/contract) to work across many CPOs
– Cross-network session authorization and start/stop control
– Exchange of tariffs and session records (CDRs) for correct billing
– Cross-border access and consistent user experience
Interoperability networks can be built through:
– Direct bilateral integrations between CPOs and eMSPs
– Roaming hubs (many-to-many) that reduce integration complexity
– Industry standards and protocols that normalize data exchange
Why Interoperability Networks Matter
Interoperability is essential for scaling public charging:
– Reduces “walled gardens” where users need many apps and contracts
– Increases charger utilization by attracting roaming users
– Improves customer trust and reduces range anxiety
– Supports cross-border travel and corridor charging
– Enables competitive markets without fragmenting access
For CPOs, interoperability can drive volume. For eMSPs, it expands coverage and customer value.
How Interoperability Networks Work
A typical interoperability session flow:
– A driver initiates charging using an eMSP credential (app/RFID, sometimes Plug & Charge)
– The CPO backend validates the credential through roaming connectivity
– Session data is recorded and shared as a Charge Detail Record (CDR)
– The eMSP bills the driver and settles payment with the CPO
– Disputes and exceptions are handled through defined processes
This depends on reliable identification, tariff transparency, and accurate timestamps.
Key Building Blocks
Interoperability networks are enabled by:
Roaming and clearing
– Roaming hubs that connect many CPOs and eMSPs
– Clearing and settlement processes for interoperability billing
– Contract frameworks and business rules between parties
Data and protocol standards
– Standard identifiers (EVSE IDs, operator IDs, contract IDs)
– Pricing and tariff models (kWh, time, session fees, idle fees)
– Standardized session record formats (CDRs)
– Security requirements for authentication and integrity
Charger-to-backend communication
While roaming is backend-to-backend, charging operations depend on:
– Charger connectivity to the CPO platform, often via OCPP
– Reliable status reporting to show availability and reduce failed sessions
– Backend uptime to prevent authorization issues
Interoperability vs Roaming
These terms are related but not identical:
– Interoperability is the broader ability for systems to work together (technical + commercial)
– Roaming is a specific interoperability use case: drivers charging across networks using a home contract
Interoperability networks typically deliver roaming, but may also enable data sharing, unified discovery, or integrated payments.
Common Challenges
Interoperability networks face recurring challenges:
– Tariff transparency mismatches and customer complaints
– CDR inconsistencies and settlement disputes
– Time zone and rounding issues impacting time-based pricing and idle fees
– Different regulatory requirements for consumer pricing and VAT invoicing
– Varying uptime and reliability across connected CPOs
– Cybersecurity risks in credential exchange and partner access
Best Practices
High-performing interoperability ecosystems usually include:
– Clear tariff publishing and version control at session start
– Strong data validation and reconciliation processes
– High backend availability and incident response coordination
– Accurate metering and compliant billing (often MID metering where relevant)
– Strong certificate and credential management for secure authentication
– Defined dispute and refund workflows
Related Glossary Terms
Interoperability
Roaming
eRoaming
CPO (Charge Point Operator)
eMSP (e-Mobility Service Provider)
Interoperability Billing
Charge Detail Record (CDR)
OCPP
Plug & Charge
Hubject