OCPP

User Guide: Integrating OCPP EV Chargers with EMHASS for Home Assistant

This guide explains how to connect OCPP-compatible EV chargers to EMHASS for smart charging and vehicle-to-grid (V2G) optimization. Learn to automate charging schedules, align EV usage with solar production, and reduce energy costs using EMHASS’s predictive algorithms.

1. Prerequisites

  • Hardware:
    • OCPP 1.6J/2.0.1-compatible EV charger (e.g., Wallbox, Zappi, ABB Terra).
    • EV supporting bidirectional charging (V2G) if applicable (e.g., Nissan Leaf, Ford F-150 Lightning).
  • Software:
    • Home Assistant (OS/Supervised recommended).
    • OCPP Integration via HACS.
    • EMHASS add-on installed and configured for solar/battery optimization.

2. OCPP Integration Setup

A. Install and Configure OCPP

  1. Install via HACS:
    • Add https://github.com/lbbrhzn/ocpp to HACS repositories.
    • Install the OCPP integration and restart Home Assistant.
  2. Add Central System:
    • Go to Settings > Devices \& Services > Add Integration > OCPP.
    • Set Host to 0.0.0.0 and Port to 9000.
    • Note the WebSocket URL (e.g., ws://192.168.1.100:9000).
  3. Connect Your Charger:
    • Configure the charger’s OCPP Central System URL to match the WebSocket URL.
    • Key entities will auto-populate:
      • Charger status: sensor.charger_status
      • Charging power: sensor.charger_power
      • Control switch: switch.charger_charge_control

3. EMHASS Configuration for OCPP Chargers

A. Define Charger as a Deferrable Load

In EMHASS’s config.json or web UI:

{  
  "deferrable_loads": {  
    "ev_charger": {  
      "entity_id": "switch.charger_charge_control",  
      "max_power": 11000,  // Charger’s max power (Watts)  
      "soc_entity": "sensor.ev_battery_soc",  // Required for V2G  
      "soc_min": 20,       // Minimum battery % for discharge  
      "soc_max": 80        // Maximum battery % for charging  
    }  
  }  
}

B. For V2G (Bidirectional Charging)

Add the EV as a battery asset in EMHASS:

{  
  "batteries": [  
    {  
      "name": "ev_battery",  
      "sensor_power": "sensor.charger_power",  // Negative = discharging  
      "sensor_soc": "sensor.ev_battery_soc",  
      "capacity_kwh": 40,  
      "max_discharge_rate": 5000  // 5kW max discharge  
    }  
  ]  
}

4. Automating with EMHASS and OCPP

A. Daily Optimization Workflow

  1. Run EMHASS Optimization:
    • EMHASS calculates charging/discharging schedules using solar forecasts and tariffs.
  2. Apply Schedule via OCPP TxProfile:
automation:  
  - alias: "Set Daily Charging Schedule"  
    trigger:  
      - platform: time  
        at: "04:00:00"  // Run before peak solar  
    action:  
      - service: rest_command.emhass_optimize  
      - delay: "00:05:00"  
      - service: ocpp.set_tx_profile  
        data:  
          charger_id: "EVSE1"  
          tx_profile:  
            schedule:  
              - start_period: "2025-06-10T10:00:00Z"  
                limit: 11000  // Charge at 11kW during solar surplus  
              - start_period: "2025-06-10T17:00:00Z"  
                limit: -5000  // Discharge 5kW during peak tariff

B. Solar-Powered Charging Automation 

automation:  
  - alias: "Charge Only on Solar Surplus"  
    trigger:  
      - platform: numeric_state  
        entity_id: sensor.pv_power  
        above: >  
            // 1kW surplus  
    action:  
      - service: switch.turn_on  
        target:  
          entity_id: switch.charger_charge_control

5. Key Entities and Services

Function Home Assistant Entity/Service EMHASS Parameter
Charger Control switch.charger_charge_control deferrable_loads.ev_charger
Charger Power sensor.charger_power Used in automations
EV Battery SOC sensor.ev_battery_soc batteries.ev_battery.sensor_soc
Set Schedule service: ocpp.set_tx_profile Linked to EMHASS outputs

6. Troubleshooting

  • Charger Not Responding:
    • Check firewall rules for port 9000.
    • Verify the charger’s OCPP URL matches the Home Assistant WebSocket address.
  • Incorrect Charging Power:
    • Confirm max_power in EMHASS matches the charger’s rating.
    • Check sensor.charger_power unit (Watts vs. kilowatts).
  • V2G Not Working:
    • Ensure the charger and EV support bidirectional charging.
    • Validate sensor.charger_power shows negative values during discharge.

7. Resources

By integrating OCPP with EMHASS, you unlock precise control over EV charging, turning your vehicle into a dynamic asset for solar optimization, grid cost reduction, and energy resilience.