OCPI roaming is EV charging roaming enabled via the Open Charge Point Interface (OCPI) protocol, allowing drivers to start charging on one operator’s (CPO) network using credentials and a contract from another provider (eMSP). OCPI roaming standardizes the exchange of charger locations, availability, tariffs, authorization tokens, sessions, and Charge Detail Records (CDRs) to enable multi-network access across platforms.
How OCPI roaming works
A typical OCPI roaming journey looks like this:
– The driver has an account with an eMSP (app and/or RFID)
– The eMSP issues a token (identifier) used for authorization
– The driver plugs in at a charger operated by a different CPO
– The CPO backend checks the token via OCPI (directly or through a roaming hub)
– If approved, the session starts and is tracked
– After the session ends, the CPO sends a CDR via OCPI for billing and settlement
What data OCPI roaming exchanges
OCPI roaming typically relies on these key data streams:
– Locations: charger sites, EVSEs, connector details, capabilities
– Status: availability updates (available, occupied, out of service, etc.)
– Tariffs: pricing rules that the eMSP can show to the driver
– Tokens: identifiers for cross-network authorization
– Sessions: live or near-real-time session data (optional but common)
– CDRs: final billing records for settlement and invoicing
Why OCPI roaming matters
OCPI roaming improves both user experience and network economics:
– Enables multi-network access without multiple apps and contracts
– Improves charger discovery and reliability of availability information
– Supports price transparency by sharing tariffs before charging
– Increases utilization for CPOs by bringing roaming users to their chargers
– Standardizes settlement flows, reducing custom integration work
OCPI roaming vs OCPP
These protocols operate at different layers:
– OCPP: charger ↔ CPMS communication (control, monitoring, transactions)
– OCPI: backend ↔ backend communication (CPO ↔ eMSP) for roaming, discovery, tariffs, sessions, and billing
Most roaming-capable networks use both.
Common challenges and failure points
– Token mapping errors causing start failures (invalid/unknown token)
– Stale status data leading drivers to unavailable chargers
– Tariff mismatches (displayed price differs from billed price)
– Incomplete or inconsistent CDR fields causing settlement disputes
– Time zone, rounding, and VAT handling differences across parties
– Unclear customer support boundaries (who handles refunds and complaints)
Best practices for reliable OCPI roaming
– Keep location/status updates frequent and accurate
– Version and synchronize tariffs with effective dates to avoid disputes
– Validate sessions and CDRs automatically (completeness, currency, VAT, IDs)
– Monitor roaming KPIs: authorization success rate, start success rate, CDR acceptance rate
– Define SLAs and exception handling processes between CPO and eMSP
– Secure API connections (TLS, allow-listing, credential rotation)
Related glossary terms
OCPI
Roaming
eMSP
CPO
Multi-network access
OCPI integration
OCPI billing
Charge Detail Record (CDR)
Tariffs and pricing models
OCPP