OCPP and Networked Charger Architecture: A Deep Dive
The Short Answer
OCPP (Open Charge Point Protocol) is the open standard that allows EV chargers from any manufacturer to communicate with any Charge Point Management System (CSMS). Understanding its message flows, smart-charging profiles, and security layers is essential for any commercial EVSE deployment.
Networked EV chargers are not just plugs in a wall — they are IoT devices running a communications protocol that controls authentication, metering, remote commands, and energy management. OCPP is the language they speak, and knowing it separates a basic install from a truly scalable charging infrastructure.
OCPP (Open Charge Point Protocol) is an open, vendor-neutral protocol that lets EV chargers (Charge Points) communicate with a central Charge Point Management System (CSMS) over a WebSocket connection. It enables remote start/stop, user authentication, energy reporting, firmware updates, and smart charging — all from a single software platform regardless of charger brand.
OCPP Versions: 1.6 vs 2.0.1
| Feature | OCPP 1.6 | OCPP 2.0.1 |
|---|---|---|
| Transport | WebSocket (JSON or SOAP) | WebSocket (JSON only) |
| Smart Charging | Basic profiles | Enhanced + ISO 15118 |
| Security | Optional TLS | TLS required, certificate mgmt |
| Device Management | Limited | Full device model |
| V2G Support | No | Yes (via ISO 15118) |
| Market Adoption (2026) | ~70% of deployed units | ~30% and growing fast |
The OCPP Architecture: Three Layers
- Charge Point (CP): the physical EVSE unit — sends status, accepts commands, reports energy data
- CSMS (Charge Point Management System): the cloud software platform — manages users, schedules, billing, and analytics
- Local Controller (optional): on-site hardware that manages load balancing across multiple chargers before routing to CSMS
Core OCPP Message Flows
Every OCPP session follows a predictable flow: the charger boots and sends a BootNotification → CSMS responds with Accepted and a heartbeat interval → driver presents credentials → charger sends Authorize request → CSMS grants or denies → charger sends StartTransaction → metering values stream periodically (MeterValues) → driver unplugs → charger sends StopTransaction with final energy delivered.
Smart Charging Profiles
OCPP's ChargingProfile message lets the CSMS or a local controller set a power limit schedule on each charger. This is the engine behind demand response, utility TOU rate optimization, and site-level load management. A charging profile specifies a stack level, schedule periods, and limit values in amps or watts — the charger must honor it in real time.
OCPP Smart Charging Enables Demand Charge Reduction
Commercial sites pay demand charges based on peak 15-minute average power draw. OCPP ChargingProfiles can cap total EVSE load during peak hours, potentially saving thousands of dollars per month on a busy fleet or retail charging site.
Security Considerations for Networked EVSE
- Always use TLS (minimum TLS 1.2, prefer 1.3) for the WebSocket connection
- OCPP 2.0.1 adds certificate-based mutual authentication — require it for new installs
- Segment EVSE on a dedicated VLAN separate from corporate or guest networks
- Ensure the CSMS vendor has SOC 2 Type II or equivalent security certification
- Keep charger firmware current — manufacturers push security patches via OCPP RemoteTrigger / FirmwareUpdate
Connectivity Options for Remote Chargers
| Connectivity | Best For | Latency / Reliability |
|---|---|---|
| Ethernet (wired) | Parking garages, fixed commercial sites | Excellent |
| Wi-Fi | Retail, hospitality near AP coverage | Good if signal is strong |
| 4G/LTE cellular | Remote sites, highway corridors | Good; adds SIM cost |
| 5G | High-density fleets, future-proof sites | Excellent; cost decreasing |
Installer Tip: Always Test Connectivity Before Commissioning
A charger that cannot reliably reach the CSMS will fall into 'offline mode' and may block user authentication. Commission every networked unit with a live WebSocket connection test and verify BootNotification acceptance before signing off the job.
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Frequently Asked Questions
Do all EV chargers support OCPP?
No — many residential Level 2 chargers are proprietary-network only or Wi-Fi-based with no OCPP support. OCPP is standard in commercial-grade networked chargers. When specifying commercial EVSE, always confirm OCPP version support in the product datasheet.
What is the difference between OCPP and OCPI?
OCPP governs the charger-to-CSMS communication (the back-end). OCPI (Open Charge Point Interface) governs CSMS-to-CSMS roaming — enabling drivers to use a charger network operated by a different provider than their account. They work together in open-standard charging ecosystems.
Can OCPP chargers work without an internet connection?
Yes, with limitations. In offline mode, chargers can be configured to allow all sessions (free vend) or block all sessions. A local controller with a cached authorization list can maintain some functionality. Full remote management and billing require a live CSMS connection.
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Michael Rivera
Texas Master Electrician with 12+ years in the trade and 500+ EV charger installations. Lead instructor at EVCharger Academy.
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