The AC charger bottleneck no one is talking about

This article was co-authored by Björn Albertsson, Metergram, and Carla Treviño, Irdeto.

When the EV industry talks about charging constraints, the conversation usually centers on the visible pressure points: fast-charging rollout, grid capacity, range and peak demand. Those issues matter. But they are not the whole story.

A quieter constraint is building in parallel across homes, workplaces and destination parking: the AC charging layer. As charging becomes more connected to authentication, energy management and trusted interaction between vehicles and infrastructure, the readiness of that installed AC base matters far more than the market often assumes.

Much of that installed AC base was not built with that shift in mind. It was designed for reliable power delivery, not necessarily for the secure, interoperable communication newer charging use cases depend on.

The next phase of charging is about intelligence

Charging is moving beyond access, speed and coverage. As features like Plug & Charge, smart charging and bidirectional energy flow become more important, the charger is becoming part of a broader connected system. That raises the bar for the infrastructure underneath.

Increasingly, a charging session may need to support secure authentication, real-time data exchange and closer coordination with energy demand, pricing or grid conditions. In some cases, it may also need to handle energy flowing both ways.

As EVs become more integrated into homes, buildings, fleets and energy systems, new services will follow. The question is whether the installed base is ready to support them.

Why AC chargers are becoming the silent bottleneck

What makes this bottleneck easy to miss is that the charger still works. The issue is whether it can support the secure, reliable communication newer charging use cases depend on, including Plug & Charge and other ISO 15118-based interactions.

Many AC chargers already in the field were not built for that kind of secure interaction. They were designed to deliver electricity safely and reliably, but not always to handle the certificate-based security and cryptographic processes these interactions require. In many cases, this becomes a hardware readiness issue.

This is why the AC constraint is easy to underestimate. The charger still starts the session and delivers power. The limitation only becomes visible when the market asks more of that infrastructure than it was designed to support.

Figure 1. Simplified view of the EV charging ecosystem and the key communication links between the vehicle, charging station, CSMS back end and e-mobility service provider.

The OCPP dimension

It’s also a protocol issue. A large share of AC chargers already in the field still run OCPP 1.6 or earlier generations. While those versions were sufficient for basic operation, they were not designed for the security profiles, certificate handling and message flows that ISO 15118 based interactions – such as Plug & Charge – depend on.

OCPP 2.0.1 introduced the standardized message types and security mechanisms that allow the CSMS to participate properly in Plug & Charge transactions. Without support for those flows at the protocol level, the charger and the trust infrastructure cannot complete the end-to-end handshake, even if both are individually capable.

Seen this way, the AC bottleneck is not a single limitation but three interdependent ones: hardware capability, protocol support and trust infrastructure. All three need to move forward together.

What a less capable AC base could constrain

What is at stake here goes well beyond any single feature.

For drivers, an existing AC charging base with a more capable interaction layer could make the process feel simpler and more consistent across different environments. While Plug & Charge is a pivotal step, the challenge lies in streamlining every touch point of the daily charging experience.

The implications are just as important on the energy side. As charging becomes more connected to wider energy systems, chargers can play a bigger role in demand management, flexibility and bidirectional participation. Smart charging and V2G are early examples of what a more responsive ecosystem could support.

There is also a wider infrastructure issue. The more uneven the installed base becomes, the harder it is to build a charging experience that feels interoperable, scalable and ready for the next layer of services. Some parts of the network move ahead while others remain constrained by earlier design decisions.

That matters even more because some of the most valuable use cases may still be taking shape, especially as EVs become more integrated into homes, buildings, fleets and energy markets.

This is why the AC bottleneck matters beyond technology alone. It will shape how much room the industry has for what comes next.

Solving this bottleneck will take more than better hardware alone

For new deployments, hardware and software readiness remain essential. If AC charging infrastructure is expected to support more secure and more capable interaction over time, that must be built in early.

Not all legacy hardware can be upgraded to support full ISO 15118 interaction, but trust infrastructure remains a necessary foundation wherever secure interaction is technically possible.

The CSMS gap

There is also a critical layer between hardware and trust that often gets overlooked: the charging station management system. This is where Plug & Charge sessions are actually processed.

If the CSMS does not implement the transaction flow correctly, nothing works, regardless of how capable the charger hardware is or whether a certificate pool is in place. The failure mode seen most often is familiar: the charger is ISO 15118 capable, the certificate infrastructure is connected, and the session still falls back to RFID or fails silently.

This is not a hardware problem or a PKI problem in isolation. It is a system integration problem. CSMS readiness needs to be verified before ISO 15118 and PKI infrastructure are brought live, not discovered afterward through failed customer sessions.

But hardware and software are only one part of the equation. The other is the trust layer underneath these interactions: certificate management, secure authentication and interoperability frameworks that allow vehicles, chargers and charging ecosystems to trust one another at scale.

This is where CrossCharge by Irdeto fits in. CrossCharge focuses on the trust infrastructure behind ISO 15118-based charging, supporting the certificate and PKI foundations that secure those interactions across OEMs, CPOs and eMSPs.

The transition is unlikely to happen through hardware replacement alone. In a market shaped by long replacement cycles and uneven infrastructure maturity, the industry will need practical ways to support a more capable ecosystem across a mixed installed base. Secure communication remains fundamental, but bridging approaches may also play an important role.

The challenge is creating an ecosystem that can support trusted interaction at a scale.

Running a mixed network in practice

Most CPO networks will operate a mixed infrastructure for years to come. New chargers with full Plug & Charge and smart charging capabilities will coexist with legacy AC units that support more limited interaction. In that reality, authentication fallback cannot be an afterthought: it needs to be designed deliberately.

If a Plug & Charge session fails and there is no graceful fallback to RFID or ad hoc payment, the failure is invisible to the operator and very visible to the driver. The charger still delivers power, the backend may log no obvious error, and yet the user experience breaks down at the worst possible moment.

This is why CPOs need an operational strategy for the mixed network, not just a roadmap for when everything is eventually upgraded. How sessions fail, how authentication degrades, and how trust is maintained across different capability levels will shape reliability in practice long before the installed base is fully modernized.

The real charging gap may be hidden in plain sight

AC charging deserves closer attention. For a long time, AC chargers were easy to treat as the simpler part of the ecosystem. As charging evolves, that view starts to look outdated.

What is already in the ground will shape the market for years to come. If too much of that infrastructure lacks the foundations for secure and interoperable interaction, it will narrow down what the next phase of charging can realistically support.

That is why AC chargers deserve more attention in the transition. The bigger constraint may already be in the ground.

Does this align with how you see the future of EV charging? Contact us to continue the conversation.