EV Charging Roaming Interoperability: Letting Drivers Charge Across Networks

A driver who owns a Tata Nexon EV and needs to get from Delhi to Jaipur shouldn’t have to install five different charging apps to make the trip. That’s the practical promise of EV charging roaming interoperability: a driver registered with one network — an eMSP’s app, a fleet’s charging card, a CPO’s own wallet — can authenticate, charge and pay at a station run by a completely different operator, with billing settled behind the scenes. For CPOs building public networks, eMSPs running driver apps, fuel retailers electrifying forecourts, and enterprise fleets routing vehicles across cities, roaming isn’t a driver-convenience feature. It’s a decision about how much of the market’s charging demand your network actually captures versus quietly hands to a rival.

Why EV Charging Roaming Interoperability Matters For Every Segment

India’s public charging market is genuinely fragmented — more than 40 CPOs, from oil marketing companies to venture-backed startups, each running their own app, tariff structure and driver base. No single operator’s app covers anywhere close to the full national charger stock. That fragmentation looks different depending on which side of the business you sit on:

For CPOs

Roaming is the fastest way to add utilization without adding sites. A charger sitting idle at 2pm because your own app’s drivers aren’t nearby can serve a visiting driver from a partner eMSP instead — the same infrastructure, more sessions.

For fuel retailers and oil & gas forecourts

You’re competing for EV traffic that isn’t loyal to any fuel brand yet. Roaming lets a driver find and charge at your forecourt through an app they already trust, without you having to win that app relationship yourself first.

For enterprise fleets

A delivery fleet running mixed routes across three cities can’t negotiate a bespoke contract with every charge point operator on every road. Roaming-enabled fleet charging management means one card or app authenticates across networks the fleet doesn’t own or manage directly.

How OCPI-Based Roaming Actually Works

Roaming is not a single feature you switch on — it’s a protocol-level handshake between a CPO’s backend and an eMSP’s backend. The Open Charge Point Interface (OCPI) is the open standard that makes this possible, maintained by the non-profit EVRoaming Foundation and free for any operator to implement. It works as a defined sequence, not a one-time integration:

• Credentials handshake: the two backends exchange tokens and base URLs via OCPI’s Versions and Credentials endpoints, establishing a trusted, authenticated connection.
• Location publishing: the CPO publishes its sites, EVSEs and connectors so the eMSP can surface them, live, inside its own driver app.
• Real-time authorization: when a visiting driver starts a session, the CPO checks the eMSP’s Token — either in real time or against a cached whitelist — before energizing the connector.
• Session streaming: live session data (energy delivered, duration, status) flows back to the eMSP so its app shows an accurate, real-time charge.
• CDR settlement: a Charge Detail Record closes the session, carrying the numbers both sides bill and reconcile against.

Most production deployments in 2026 run OCPI 2.2.1, released in 2020; version 2.3 arrived in February 2025 and adoption is growing, with 3.0 expected to add ISO 15118 and Plug & Charge support to the roaming layer itself. It’s worth separating OCPI from OCPP here — OCPP governs communication between a charger and its own Central Management System (maintained by the Open Charge Alliance), while OCPI governs the roaming relationship between two different operators’ backends. A CPO needs both: OCPP to run its own network, OCPI to open it to others.

Two Ways To Open Your Network: Bilateral Deals vs. Roaming Hubs

CPOs choose between two structurally different roaming business models, and most networks end up using both at different stages of growth.

Bilateral agreements

Two operators connect directly, negotiating their own revenue share, tariff visibility and settlement cycle. This is how India’s roaming network has largely grown so far — ChargeZone, for example, has expanded to more than 13,500 stations through direct OCPI-based partnerships with Statiq, Bolt.Earth, Kazam and Pulse Energy. Bilateral deals give both sides full control over terms, but every new partner is a separate negotiation and a separate technical connection — it scales linearly, not exponentially.

Roaming hubs

A roaming hub sits between many CPOs and many eMSPs, so one technical integration connects an operator to the hub’s entire partner base instead of to each partner individually. Globally, hub-based roaming already operates at real scale: Hubject connects over a million charging points across more than 2,750 partner networks in 70-plus countries, while Gireve’s February 2026 roaming barometer reported roughly 695,000 connected charging points, and e-clearing.net around 445,000 across 1,200-plus partners. The trade-off is that the hub, not the CPO, controls much of the technical and commercial standardization — useful for reach, less useful if a CPO wants bespoke terms with a specific partner.

What CPOs Gain By Opening Up To Roaming

The upside case for roaming is straightforward, but it’s worth quantifying by segment rather than treating it as one generic benefit:

• Incremental utilization, not incremental infrastructure: visiting-network sessions fill capacity your own app’s driver base wasn’t going to use anyway — pure upside on assets already deployed.
• A new settlement-fee revenue line: roaming interchange and hosting fees add a recurring, low-effort revenue stream on top of per-session charging revenue.
• Wider driver reach without owning the app relationship: a CPO doesn’t need to win every driver’s app download to serve that driver — the eMSP already did that work.
• A competitive differentiator for fuel retailers: forecourts entering EV charging late can still capture EV traffic immediately by being visible inside established eMSP apps, rather than waiting to build brand loyalty from zero.
• Simpler multi-city coverage for fleets: enterprise fleets get one authentication layer across networks they don’t need to own, which is the whole point of roaming from the demand side.

The Risk Side: Revenue-Share And Reconciliation Complexity

Roaming’s downside rarely shows up as a technical failure — OCPI is a mature, well-documented protocol. It shows up as operational and financial friction once volume grows:

• CDR mismatches: if a CPO’s and an eMSP’s Charge Detail Records disagree on energy delivered or session duration, disputed sessions pile up faster than manual reconciliation can clear them.
• Tariff transparency disputes: a driver charged a roaming markup they didn’t expect complains to the eMSP, who complains to the CPO — the CPO’s brand absorbs a support cost it didn’t directly cause.
• Settlement-cycle mismatch: hub and bilateral partners often settle on different cycles (weekly vs. monthly), which complicates cash-flow forecasting for smaller CPOs.
• Authentication and token security: real-time Token authorization is safer but adds latency; cached whitelists are faster but stale entries create a fraud window if not refreshed on a tight schedule.
• Brand dilution: a bad charging experience on a partner’s hardware still reflects on the eMSP’s app the driver trusted — reputational risk flows in both directions in a roaming relationship.

None of this argues against roaming — it argues for treating CDR reconciliation and tariff-rule configuration as first-class operational processes, not an afterthought bolted onto a technical integration.

India’s Regulatory Push Toward Mandatory Interoperability

Interoperability in India is moving from a technical best practice to policy expectation. The Ministry of Power’s 2024 Guidelines for Installation and Operation of EV Charging Infrastructure keep public charging an unlicensed activity while explicitly directing operators toward open protocols — OCPP for charger-to-CMS communication and OCPI for cross-network roaming. That’s a deliberate signal: the government wants a connected national network, not isolated proprietary islands.

The clearest evidence that this is becoming infrastructure, not just guidance, is Unified Bharat e-Charge (UBC) — an open interoperability layer being built by the Ministry of Heavy Industries, with BHEL as the nodal agency for demand aggregation and NPCI providing the settlement rails, modeled explicitly on UPI’s single-interface approach to payments. Once live, a driver will be able to discover chargers, check live availability and tariffs, and pay across participating networks — already lined up include Tata Motors, Tata Power, Mahindra, Maruti Suzuki, IOCL, BPCL, HPCL, ChargeZone, Bolt.Earth and Statiq — through one compatible app instead of five. In July 2026, Kazam launched a free seven-day integration programme specifically to help smaller CPOs onboard onto UBC without integration cost being the barrier, covering OCPI protocol enablement, sandbox testing and certification.

The practical takeaway for CPOs: OCPI compliance built today is not just for today’s bilateral or hub partnerships — it’s the same technical foundation UBC will expect operators to already have when the national layer expands beyond its current partner list.

Operationalizing Roaming: What To Look For In Your CMS

Roaming only pays off if the software running it treats OCPI as a native capability rather than a bolt-on integration project. A charging management system worth building a roaming strategy on should provide, at minimum:

• Native OCPI roaming integration at the current 2.2.1 specification, not a third-party middleware layer bolted onto an older core.
• Automated CDR generation and reconciliation, so disputed sessions get flagged and resolved in days, not manually chased down weeks later.
• Configurable tariff and revenue-share rules per roaming partner, instead of one blanket rate applied to every eMSP relationship.
• Real-time Token authorization with a cached-whitelist fallback for connectivity gaps, so a network outage doesn’t strand a visiting driver mid-session.

This is precisely what YoCharge’s EV roaming network module is built to operationalize for CPOs — OCPI 2.2.1 support, automated settlement and per-partner tariff rules sitting inside the same dashboard used to run day-to-day operations, rather than as a separate system to reconcile against manually. Roaming, in other words, isn’t a bolt-on feature — it’s one module inside a broader EV charging management platform like YoCharge’s EV-CMS, alongside billing, load management and remote monitoring. For a deeper technical primer on interoperability standards themselves, see YoCharge’s EV charging interoperability guide.

Sources: EVRoaming Foundation — OCPI protocol | Open Charge Alliance — OCPP | Ministry of Power — EV Charging Infrastructure Guidelines 2024 | Energetica India — Unified Bharat e-Charge integration drive

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