EVCC · Self-Consumption · Fronius · SMA · SG Ready · KNX · 10 min read

EVCC Self-Consumption EV Charging with KNX: Fronius Modbus and SG Ready Coordination

EVCC (Electric Vehicle Charge Controller) is an open-source self-consumption controller that reads live PV generation from Fronius or SMA inverters via Modbus TCP and automatically adjusts EV charge current to match surplus solar export — integrated with KNX via the EVCC KNX plugin for mode switching and status monitoring from the building automation layer.

EVCC overview: what it does and how it runs

EVCC is an open-source project (github.com/evcc-io/evcc) that acts as a dedicated self-consumption controller for electric vehicle charging. It connects to the solar inverter to read real-time generation and grid power, connects to one or more EV chargers via OCPP or native APIs, and continuously adjusts charge current to maximise the fraction of solar energy used for EV charging rather than exported to the grid.

EVCC runs as a Docker container or as a Home Assistant add-on, making it straightforward to deploy on a Raspberry Pi 4 alongside Home Assistant. The EVCC web dashboard provides real-time visualisation of PV power, grid flow, battery SOC, and EV charging state. For KNX integration, the EVCC KNX plugin — enabled in evcc.yaml — publishes EVCC state variables to KNX group addresses and reads mode selection GAs from KNX pushbuttons.

EVCC deployment options

  • Raspberry Pi 4 (4GB): EVCC as Docker container, runs 24/7 on ~4W
  • Home Assistant OS: EVCC official add-on, single server setup
  • Synology NAS: Docker container in Container Manager
  • Proxmox VM: Docker or native Linux binary for homelab setups

EVCC vehicle support (partial list)

  • Tesla (Model 3, Model Y, Model S) — via Tesla API
  • VW ID.4, ID.3 — via WeConnect API
  • Hyundai Ioniq 5, Ioniq 6 — via Bluelink API
  • BMW iX, i4 — via BMW ConnectedDrive API
  • Generic vehicle (no API): fixed 80% battery limit

Fronius GEN24 Modbus configuration in evcc.yaml

EVCC reads the Fronius GEN24 inverter via SunSpec Modbus TCP using the built-in Fronius meter type. The configuration requires a static IP for the inverter and Modbus TCP enabled in the Fronius webserver settings panel.

evcc.yaml — Fronius GEN24 meter and charger configuration

meters:
  - name: fronius_pv
    type: template
    template: fronius-symo
    uri: http://192.168.1.100   # Fronius static IP
    usage: pv                   # PV generation meter

  - name: fronius_grid
    type: template
    template: fronius-smart-meter
    uri: http://192.168.1.100
    usage: grid                 # Grid import/export meter

  - name: fronius_battery
    type: template
    template: fronius-battery
    uri: http://192.168.1.100
    usage: battery              # Battery SOC + charge power (GEN24 Plus only)

chargers:
  - name: easee_home
    type: template
    template: easee
    user: user@email.com
    password: EaseeAppPassword
    charger: XXXXXXXX           # Easee charger serial number

vehicles:
  - name: my_tesla
    type: template
    template: tesla
    title: Tesla Model 3
    accessToken: <Tesla API token>
    refreshToken: <Tesla refresh token>

site:
  title: Home
  meters:
    grid: fronius_grid
    pv: fronius_pv
    battery: fronius_battery
  loadpoints:
    - title: EV Charger
      charger: easee_home
      vehicle: my_tesla
      mode: pv                  # Default: PV-only self-consumption mode
      minCurrent: 6             # Minimum 6A (1.38kW @ 230V)
      maxCurrent: 16            # Maximum 16A (3.68kW @ 230V)

evcc.yaml — SMA Energy Meter alternative

# SMA Sunny Boy + SMA Energy Meter
meters:
  - name: sma_pv
    type: template
    template: sma-sunnyboy
    uri: https://192.168.1.101   # SMA inverter static IP (HTTPS)
    password: <SMA web UI password>
    usage: pv

  - name: sma_grid
    type: template
    template: sma-energymeter
    # SMA Energy Meter uses Multicast UDP — no IP config needed
    serial: 1234567890           # Serial from SMA Energy Meter label
    usage: grid

EVCC KNX plugin: enabling and configuring

The EVCC KNX plugin connects EVCC to the KNX bus via a KNX IP interface (KNXnet/IP tunnelling or routing). It publishes EVCC loadpoint state to KNX group addresses and listens for mode commands from KNX pushbuttons or automation scenes. Enable it in evcc.yaml under the messaging or plugins section.

evcc.yaml — KNX plugin configuration

# evcc.yaml — KNX plugin section
knx:
  gateway: 192.168.1.10   # KNX IP interface / IP router static IP
  # or use: gateway: 224.0.23.12 (KNX multicast for IP routing)

  # Mode selection GAs — written by KNX pushbutton or automation
  # Values: 0=off, 1=now (fast), 2=minpv (min+pv), 3=pv (solar only)
  mode: "10/1/0"

  # Status GAs — published by EVCC to KNX (read-only from KNX side)
  activeMode: "10/1/1"         # Current active mode (DPT 5.010)
  charging: "10/1/2"           # Charging active boolean (DPT 1.001)
  chargePower: "10/1/3"        # Current charge power W (DPT 13.010)
  sessionEnergy: "10/1/4"      # Session energy kWh (DPT 14.056)
  vehicleSoc: "10/1/5"         # Vehicle SOC % (DPT 5.001, if API connected)
  pvPower: "10/1/6"            # PV power W from inverter (DPT 13.010)
  gridPower: "10/1/7"          # Grid power W signed (DPT 13.010)
EVCC ModeKNX valueBehaviourTrigger from KNX
off0No charging — EV disconnected from scheduleLong press pushbutton or manual override
now (fast)1Charge at maximum current regardless of solarShort press: 'Charge Now' scene
minpv2Charge at minimum (6A) + increase with solar surplusShort press: 'Min + Solar' scene
pv3Solar-only: suspend below 6A threshold, resume when surplusDefault / KNX schedule at 09:00

SG Ready heat pump coordination: priority logic

When both EVCC (controlling EV charging) and SG Ready (controlling heat pump) compete for the same PV surplus, a priority arbitration layer prevents grid import while maximising total self-consumption across both loads. The coordination logic runs in KNX (MDT Logic Module) or Home Assistant automations using EVCC's KNX status GAs.

SG Ready + EVCC priority coordination logic

Source data from KNX GAs (all published by EVCC KNX plugin):
  GA 10/1/6 = PV power W (from Fronius Modbus)
  GA 10/1/7 = Grid power W (negative = export, positive = import)
  GA 10/1/3 = Current EV charge power W

Priority logic (KNX Logic Module or HA automation):

STEP 1 — Heat pump base load:
  IF GA 10/1/7 < −500W (exporting > 500W):
    → SG Ready State 3 (S2=1, S1=0) = encouraged mode
    Heat pump increases setpoint by +2°C, absorbs ~1 kW extra

STEP 2 — EV charging from remainder:
  Available for EV = GA 10/1/7 (grid export W) − 0W margin
  IF available > 1400W (enough for 6A minimum):
    → Write EVCC mode=pv to GA 10/1/0 (value 3)
    EVCC automatically adjusts current to use remaining surplus

STEP 3 — Maximum surplus (SG Ready State 4):
  IF GA 10/1/7 < −6000W AND EVCC charging at maximum (16A):
    → SG Ready State 4 (S1=1, S2=1) = maximum HP power
    Heat pump runs at rated capacity, absorbs 3–6 kW additional

STEP 4 — Grid import prevention:
  IF GA 10/1/7 > +200W (importing more than 200W):
    → SG Ready → State 2 (normal, reduce heat pump load)
    → If still importing after 60s: EVCC mode=off (suspend EV)
    Prevents the heat pump + EV combination from causing grid import

EVCC ABB Terra charger configuration

ABB Terra AC chargers (11 kW and 22 kW) are commonly specified in commercial KNX buildings. EVCC supports ABB Terra via OCPP 1.6J using the same configuration approach as Easee, with a slightly different OCPP connection URL format.

evcc.yaml — ABB Terra charger configuration

chargers:
  - name: abb_terra_1
    type: template
    template: ocpp
    id: ABBTerra01              # Charge point ID configured in ABB Terra
    # ABB Terra OCPP central system URL in charger settings:
    # ws://192.168.1.200:8887/ABBTerra01
    maxCurrent: 32              # ABB Terra AC W22 max 32A 3-phase

# ABB Terra specific: enable OCPP in charger web UI
# URL: http://<ABB-terra-IP>/configuration
# OCPP Central System URI: ws://evcc-server-ip:8887/ABBTerra01
# OCPP version: OCPP16 (select from dropdown)

EVCC dashboard with KNX status group addresses

The EVCC web dashboard (accessible at http://evcc-server-ip:7070) provides live self-consumption visualisation. For KNX visualisation systems (Gira X1, IP-Symcon, ARISTO BewO), the EVCC KNX status GAs feed real-time data to panel displays and mobile app dashboards.

KNX visualisation integration for EVCC status

Gira X1 / Gira HomeServer visualisation page:
  Display widget: "PV Power" → reads GA 10/1/6 (DPT 13.010 W)
  Display widget: "Grid Power" → reads GA 10/1/7 (DPT 13.010 W)
  Display widget: "EV Charging W" → reads GA 10/1/3
  Toggle button: "Charge Mode" → writes 1/2/3 to GA 10/1/0
  Indicator lamp: "Charging Active" → reads GA 10/1/2 (DPT 1.001)

IP-Symcon dashboard:
  Create KNX variables linked to EVCC GAs
  Dashboard widget type: Gauge (PV Power, 0–10000W)
  Dashboard widget type: LED indicator (Charging Active)
  Dashboard widget type: Selector (Mode: Off/Now/MinPV/PV)
  → Variable change triggers IPS script to write GA 10/1/0

KNX touch panel (e.g. Gira e2 or MDT IP touch panel):
  EV charging page with live power values
  Mode selector from page pushbutton widgets
  Session energy total shown in kWh display element

Commissioning with live PV data

EVCC commissioning should be performed on a day with active solar generation to verify that the complete chain — from Fronius Modbus data through EVCC logic to OCPP current adjustment and KNX GA updates — functions correctly under real operating conditions.

EVCC commissioning test sequence

Step 1 — Inverter data verification:
  Open EVCC dashboard (http://evcc-ip:7070)
  Confirm: PV power > 0W on sunny morning by 10:00
  Confirm: Grid power negative (exporting) when PV > building load
  Cross-check: EVCC PV power should match Fronius webserver ±5%

Step 2 — Charger connection test:
  Plug EV into charger
  EVCC dashboard: Loadpoint shows "Connected" status
  Vehicle SOC displayed (if API configured)

Step 3 — PV mode test:
  Set EVCC mode: PV (write 3 to GA 10/1/0 from ETS6)
  Observe: EVCC begins charging when surplus > 1.4 kW
  EVCC dashboard: current slider visible and tracking solar

Step 4 — KNX status GA verification:
  ETS6 Group Monitor: watch GA 10/1/3 (charge power)
  Verify: value updates every 30 seconds as current changes
  Watch GA 10/1/2: confirms 1 (true) when EV charging active

Step 5 — Mode switching from KNX:
  ETS6 → write 1 to GA 10/1/0 (mode: now/fast)
  Confirm: EVCC dashboard shows "Now" mode, current jumps to 16A
  Write 3 back → confirm PV mode resume, current reduces to surplus-matched level

Step 6 — SG Ready coordination test:
  With EV charging at 6A (low surplus): confirm SG Ready stays at State 2
  With >3kW surplus: confirm SG Ready activates State 3
  Confirm EV current increases alongside SG Ready activation

Related guides

EV Charging & Load Management

Easee Home and Wallbox Pulsar KNX Integration via OCPP 1.6J Gateway

EV Charging & Load Management

Dynamic Load Management for Multiple EV Chargers with KNX

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