Beyond basic connectivity
Reflections from the EVRoaming & OCPI Europe event on version fragmentation, tariff challenges, and why financial correctness still isn’t guaranteed.
Open standards like OCPI have played a critical role in making EV roaming possible. They allow mobility service providers (MSPs) and charge point operators (CPOs) to connect across networks and give drivers access to charging infrastructure at scale. That foundation is working well.But as it became clear during conversations at the recent EVRoaming & OCPI Europe event in London, the industry has moved beyond basic connectivity. The real challenge now lies in what happens after systems connect, particularly around consistent interpretation and financial outcomes.
As the ecosystem grows, standards continue to evolve, pricing models become more sophisticated, and new use cases emerge. At the same time, this progress is adding new layers of operational complexity, making financial correctness harder to maintain.
Interoperability is working, but the ecosystem is still fragmented
One of the clearest points reinforced during the event in London was that many companies are still operating on different versions of OCPI. A lot of operators continue to work with OCPI 2.1.1, while newer systems use 2.2.1.
Released in February 2025, OCPI 2.3.0 adds better support for AFIR rules and National Access Points. However, moving to a newer version requires updating systems and adapting existing implementations, and not every company sees enough immediate value to justify that effort.
In practice, this means companies must interpret and process data coming from different versions of the same protocol. The ecosystem is not broken, but it requires far more normalization and interpretation than the term “standard” suggests.
Flexibility enables innovation, but also inconsistency
Tariffs are one of the best examples of this challenge. OCPI gives charge point operators a lot of freedom to create their own pricing structures. This includes time-of-use rates, idle fees, energy limits, and different pricing for AC and DC connectors at the same location.
This freedom helps create new pricing ideas that can support the grid or influence driver behaviour. But it also means tariffs can be hard to understand and compare between systems. Some structures are technically correct but confusing, while others work fine on their own but cause problems once shared with partners.
The industry is working on clearer guidelines to simplify tariff structures. At the same time, new features like the Discount Feature are being added in version 2.3 and later. This would allow CPOs to offer discount plans to drivers through MSPs, creating an incentive for drivers to charge more frequently with that CPO. While commercially attractive, it also adds another layer of complexity for MSPs in pricing, settlement, and fraud control.
From standards to usability: why tools matter
This growing complexity became visible during one session focused on tariff complexity and how it can be reduced through clearer specification guidelines and simpler structures. As part of that discussion, the EVRoaming Foundation highlighted the open-source OCPI Tariffs Calculation Tool, built by TandemDrive, as a practical way to make tariff structures more understandable and show how they affect the pricing of Charge Detail Records (CDRs).
The tool allows operators to simulate pricing by applying tariffs to CDRs, validate tariff structures, and flag common issues or inconsistencies. In a landscape where tariffs can quickly become difficult to interpret, this kind of transparency becomes essential.
It was well received by attendees, not just as a technical solution, but as a reflection of a broader need across the industry: tools that bridge the gap between what standards enable and what operators can realistically manage. Even as OCPI evolves, making it usable in practice still requires additional layers of interpretation and validation.
The challenge is no longer just data exchange
OCPI enables data exchange, but it does not guarantee how that data is interpreted. A tariff can be sent correctly. A charging record can be received correctly. A connection can be technically compliant. And yet the financial outcome can still be unclear or inconsistent.
This is where financial correctness becomes critical, and why open standards alone cannot guarantee it.
As pricing includes more variables such as time-based logic, idle fees, connector differences, and dynamic changes, differences between CPO-calculated CDR costs and MSP pricing become more common. Within TandemDrive systems, these exceptions are flagged as dropouts, requiring manual investigation and direct conversations with partners to resolve. As charging volumes increase, this quickly becomes difficult to manage at scale.
Simplicity for drivers depends on backend complexity
For drivers, the expectation is simple: find a charger, understand the price, start a session, and get billed correctly.
Behind that experience sits significant complexity.
Location data, tariff structures, session records, and pricing logic all need to align across systems that may not be fully synchronized. The more seamless the experience becomes on the front end, the more complexity needs to be absorbed in the background.
This is not a flaw. It is a sign of a maturing ecosystem. But it makes operational control more important over time.
Why financial correctness matters more at scale
When pricing and session data do not align, the impact is not just technical. It creates operational and financial work.
Deviations still need to be investigated. Differences still require reconciliation. In many cases, this involves manual follow-up between partners. As volumes grow and pricing becomes more dynamic, these issues become harder to manage.
TandemDrive works in exactly this area. It helps normalize data across different OCPI versions, interpret complex tariffs, validate CDRs, and clearly explain any differences. This reduces manual reconciliation while leaving existing roaming infrastructure unchanged.
What comes next
Open standards will continue to evolve, and the ecosystem will continue to grow.
At the same time, complexity will increase. New protocol versions, new pricing models, and new integrations will add further layers to an already dynamic system. Improvements in driver experience may also require broader integrations, including better alignment between charging infrastructure, apps, and even vehicle data.
The industry has largely solved the problem of connectivity.
The next challenge is ensuring that what flows between connected systems is consistent, understandable, and financially correct.
A shift from connectivity to control
EV roaming is no longer just about enabling access. It is about managing complexity at scale.
Open standards remain essential, but they are not the whole solution. As the ecosystem matures, the focus is shifting toward control, validation, and correctness behind the scenes.
Connectivity opened the door. The next phase is about making the system work reliably once everything is connected.