ISO 15118-20 vs ISO 15118-2: The Plug & Charge Roadmap CPOs Should Plan Around

ISO 15118-20 vs ISO 15118-2: The Plug & Charge Roadmap

Every CPO and eMSP evaluating a hardware refresh or vendor RFP this year eventually runs into the same question: does new charging equipment need to support ISO 15118-20, or is the current ISO 15118-2 deployment still good enough? The honest answer depends on your market, your V2G roadmap, and your procurement timeline — and getting it wrong in either direction is expensive, either through premature over-spec or a hardware refresh you didn’t budget for.

This is a technical-decision-maker’s guide, not a spec walkthrough. If you’re a CPO or eMSP technology lead weighing a platform roadmap, or a hardware/procurement stakeholder writing the next charger RFP, this post lays out what actually changes between ISO 15118-2, its DIN SPEC 70121 predecessor, and ISO 15118-20 — and gives you a straight framework for deciding whether to move now or wait.

What ISO 15118-2 Handles Today — And Where DIN 70121 Fits

ISO 15118-2, published in 2014, is the current, widely-deployed Plug & Charge standard for both AC and DC charging. The vehicle and the charger authenticate over Power Line Communication (PLC) using X.509 digital certificates — no RFID card, no app tap, no membership fob. The driver plugs in, the session authenticates and bills automatically, and that’s the whole interaction. It supports optional TLS (version 1.2) for the Plug & Charge handshake, and in practice almost every real Plug & Charge deployment runs it, since the certificate exchange depends on it.

DIN SPEC 70121: the DC-only predecessor still running in the field

DIN SPEC 70121 (2012–2014) was Germany’s pragmatic stopgap — a DC-only communication dialect that let early CCS fast chargers exchange charging parameters before ISO 15118-2 was ready to ship. It has no TLS, no digital certificates, and no Plug & Charge capability; it simply negotiates voltage, current, and charging-mode basics between vehicle and charger. A meaningful share of CCS DC hardware installed before roughly 2018–19 still runs DIN 70121 only, and most modern chargers keep it as a fallback compatibility mode for older EVs that never got an ISO 15118-2 software update.

For most CPOs today, this is the baseline: if your DC hardware shipped in the last several years, it almost certainly speaks ISO 15118-2 already, with DIN 70121 running underneath as a legacy handshake for older vehicles. That baseline is not what the newer standard changes — what changes is everything Plug & Charge was never built to do in the first place.

What ISO 15118-20 Actually Adds

ISO 15118-20, finalized in 2022, is not a point release — it’s a second-generation communication standard built for a grid-interactive charging network rather than a one-directional fill-up. Three changes matter most for a CPO’s decision.

Bidirectional power flow: V2G, V2H, V2B

ISO 15118-20 is the first version of the standard that can carry a discharge session, not just a charge session. It defines Vehicle-to-Grid (the EV exports power back to the public utility grid through the charger), Vehicle-to-Home (the EV powers household loads directly), and Vehicle-to-Building (the EV supplies a commercial building’s loads). None of this is possible on ISO 15118-2 — the message set simply has no concept of the EV as a power source, only as a load.

Mandatory mutual TLS 1.3 and larger certificates

Where ISO 15118-2 treats TLS as an optional add-on for Plug & Charge, ISO 15118-20 makes mutual TLS 1.3 authentication mandatory for every session. That means both the vehicle and the charging station always authenticate each other with certificates — tighter security, but also materially larger certificate payloads and a heavier cryptographic workload than most ISO 15118-2 secure elements were designed to carry.

Multiple simultaneous contracts and dynamic control

This is the detail that matters most for fleet operators: a single EV can now present more than one e-mobility contract certificate at once, and let the charging station pick the right one based on tariff, roaming agreement, or whether the vehicle is charging at a company depot versus a driver’s home. A fleet vehicle can carry both a corporate billing contract and a personal one without the driver doing anything. The newer standard also introduces a “Dynamic” control mode, where the EV yields charging-rate control to the station’s backend entirely — useful for load-balanced depot charging and demand-response participation without driver input. It adds wireless power transfer (WPT) and pantograph docking for automated bus charging too, though those matter mainly to transit-specific hardware.

The Regulatory Clock: AFIR’s 2026 and 2027 Deadlines

The reason this comparison isn’t purely academic is the EU’s Alternative Fuels Infrastructure Regulation (AFIR), Regulation (EU) 2023/1804. It sets binding hardware deadlines, not guidance: ISO 15118-2 support is required on all new public AC charging points from January 8, 2026, and ISO 15118-20 support is required on all new public and private chargers — AC and DC — from January 1, 2027. For any CPO or hardware OEM shipping into the EU or UK, that second date is closer than it looks once you account for an 8–14 month hardware design cycle.

Hardware and Certification Reality in 2026

Concretely, an ISO 15118-20-compliant charger needs a PLC-capable CCS communication controller, a secure element sized for TLS 1.3 and its larger certificates, a full TLS 1.3 stack, backend integration through OCPP 2.0.1 or newer, and a signed relationship with at least one PKI root certificate authority (Hubject and Eonti are the two most commonly cited today). That backend requirement is worth flagging on its own — if your CPMS platform hasn’t made the OCPP 2.0.1/2.1 jump yet, that upgrade decision and this one are really the same conversation; we cover the OCPP side of that roadmap separately in our OCPP 2.1 vs OCPP 2.0.1 upgrade guide.

Testing capacity is the other bottleneck. Fewer than ten labs worldwide are currently accredited for full ISO 15118-20 conformance testing, and booking a slot runs 6–9 months out. CharIN — the industry body that governs interoperability testing for the standard — is running “Testivals” in Sacramento (North America) and South Korea (Asia) through 2026 specifically to give vendors real-world interoperability checks ahead of formal certification schemes catching up to demand. If that support is anywhere on your 2027 hardware roadmap, the test-lab queue — not the engineering — is the step to start first.

Should You Upgrade Now or Wait? A Decision Framework

Strip away the spec detail and this comes down to four practical questions for your next hardware RFP or platform review:

You’re deploying new DC hardware into the EU or UK after 2026

Specify ISO 15118-20-capable hardware in the RFP now. Between the 6–9 month conformance-test queue and standard manufacturing lead times, “we’ll add it later” is not a realistic fallback once you’re inside 12 months of the January 2027 deadline.

V2G, V2H, or fleet-to-grid pilots are on your 18–24 month roadmap

Prioritize ISO 15118-20 hardware regardless of geography. Bidirectional power transfer literally does not exist in ISO 15118-2 — there’s no version of “wait and see” that gets you V2G on the older standard.

You run a stable AC/DC network today with no V2G ambitions and no EU exposure

ISO 15118-2, with DIN 70121 as a legacy fallback, remains fully compliant and fully supported. There’s no operational reason to force an early hardware refresh — but write an ISO 15118-20 upgrade option into new vendor contracts so you’re not locked out later.

Whichever camp you’re in, ask vendors these four questions directly

What’s their certificate-provisioning path and which root CA do they work with? Is their TLS 1.3 stack already in a conformance-test queue, and where in it? Is the backend OCPP 2.0.1/2.1 compatible? And can the current board be upgraded, or does -20 support require a hardware SKU change? Vendors that can’t answer these cleanly are further from shipping than their marketing suggests.

Where This Roadmap Is Headed: Plug & Charge Meets V2G

The practical takeaway is that ISO 15118-2 and ISO 15118-20 aren’t rival standards — they’re sequential generations of the same idea, Plug & Charge, with the newer generation extended to treat the EV as a two-way energy asset instead of just a load. A network built on a Plug & Charge software stack today is already halfway to a bidirectional-ready network tomorrow; the gap is the hardware and certificate layer this post has walked through, not the underlying business model.

If V2G, V2H, or fleet-to-grid services are anywhere on your roadmap, it’s worth treating the ISO 15118-20 hardware decision and your V2G and V2H charging software plans as one procurement conversation rather than two — the charger that can’t speak it is the charger that can never sell energy back, no matter how good the software layer above it is. Procurement decisions made this year quietly decide whether your network can offer that service in 2028.

Frequently Asked Questions

Sources: CharIN — ISO/IEC 15118 Communication Standard | CharIN Position Paper — Clarifying ISO 15118 Implementation Under AFIR | EUR-Lex — Regulation (EU) 2023/1804 (AFIR) | Wikipedia — ISO 15118