OCPI & Roaming: How Networks Talk So Drivers Don’t Think About It (2025)

Q: Is OCPI mandatory?

No, but it’s the de‑facto European way to interconnect apps and networks.

Q: Does OCPI set prices?

No. It transports tariffs. The CPO sets site prices; MSPs may apply memberships/fees.

Q: Is this Plug & Charge?

No. Plug & Charge (ISO 15118) authenticates the car↔charger. OCPI is operator↔app so you can discover, start and get billed.

The day the wallet of RFIDs died

Once upon a time, cross‑border EV trips meant five apps and a fistful of tags. In 2025, most of that friction is hidden by a behind‑the‑scenes language called OCPI. As one roaming foundation puts it, “OCPI enables information exchange between e‑mobility service providers and charge point operators.” The promise: one account, many networks — and drivers barely notice the plumbing.

Why this matters now

Two things converged. First, AFIR rules made ad‑hoc access and per‑kWh price display at high‑power sites the European baseline. Second, OCPI adoption by operators and apps matured, so roaming works more like payments than a tech experiment. Put simply: ad‑hoc lets anyone pay; roaming is what makes planning, discounts and one invoice possible.

OCPI in one page (what it is — and isn’t)

OCPI (Open Charge Point Interface) is a business‑layer protocol between companies (operator ↔ app). It carries Locations, Tariffs, Tokens, live Sessions and final CDRs for billing/settlement.
Not OCPP. OCPP runs the charger ↔ operator backend (status, commands, firmware). OCPI links operator ↔ app/network so a driver can find, start, pay and get a receipt. Most networks use both.

Quote (OCA explainer): “OCPP connects charge points to a central system… OCPI is used between service providers and charge point operators.”

How networks interconnect (bilateral vs hub)

Bilateral (peer‑to‑peer). A CPO and an MSP exchange credentials and open an OCPI link directly. Pros: control, fewer intermediaries. Cons: many links to reach many drivers.

Hub model. A roaming hub routes OCPI traffic among many CPOs/MSPs. Pros: one integration → many partners. Cons: extra fees/layer.

In Europe, both models run side by side; hubs speed coverage, while direct links serve strategic partners and special pricing.

A roaming charge, step by step (from the driver’s seat)

Discovery — Your app lists stations via OCPI Locations (power, plugs, hours) and Tariffs (kWh, idle, session fees).
Authorisation — You press Start. The app (MSP) sends your Token to the operator (CPO) for a yes/no.
Session — Power flows; the CPO streams a Session to your app (kWh, timestamps).
Stop → CDR — When you stop, the CPO issues a Charge Detail Record; the app invoices you (or your employer).
Settlement — CPO↔MSP reconcile; hubs route the transaction if in use.

Price reality: Apps should show ad‑hoc price vs roaming price side‑by‑side. Sometimes on‑site ad‑hoc wins; other times membership/loyalty via roaming is cheaper. Transparency earns trust.

Where things break (and how mature networks fix them)

No authorisation (token not whitelisted, link down). Fix: retry once; offer ad‑hoc fallback or a nearby site.
Tariff mismatch (stale cache). Fix: refresh Tariffs pre‑start; push updates frequently.
Stuck session (OCPP ended late). Fix: app offers remote stop; operator reconciles with a corrected CDR.
Ghost availability (closed car park). Fix: maintain access/hours in Locations; show last‑updated timestamps in UI.

Reporter’s note: studies on public charging reliability still find double‑digit failure rates, but trendlines are improving as payment and roaming stacks converge.

AFIR vs roaming — the clean way to explain it to readers

AFIR = access: card/contactless at ≥50 kW DC sites; clear per‑kWh energy pricing; secure web/QR flows often used at AC.
Roaming = experience: plan across networks, keep one account & invoice, apply fleet policies, get loyalty rates, see live availability/congestion.
Good apps let you choose on the day: tap card, or start via account.

For fleets & site hosts (what to ask vendors)

Fleet: demand one‑invoice OCPI integrations, policy controls (who can DC, time windows, geofences) and exportable CDRs for audit.
Hosts/cities: enable roaming to lift utilisation; keep Locations rich (amenities, hours, access). Display kWh price and idle fees up front; align on‑site and in‑app info.

Quick FAQ

Is OCPI mandatory? No, but it’s the de‑facto European way to interconnect apps and networks.

Does OCPI set prices? No. It transports tariffs. The CPO sets site prices; MSPs may apply memberships/fees.

Is this Plug & Charge? No. Plug & Charge (ISO 15118) authenticates the car↔charger. OCPI is operator↔app so you can discover, start and get billed.

Sources / Further reading