Solar fotovoltaica y KNX: Integración Modbus Fronius Symo para optimización del autoconsumo

Habilitación de Modbus TCP en el inversor Fronius

1. Connect to inverter webserver: http://<inverter-IP>
   (default IP shown on inverter display → Settings → Network)

2. Navigate to: Settings > Modbus
   Enable Modbus TCP: ON
   TCP port: 502 (default, leave unchanged)
   SunSpec model: enabled

3. Key holding registers (read-only):
   Register 40070 → AC power output     (int16, W)
   Register 40080 → AC energy today     (uint32, Wh)
   Register 40225 → Grid power          (int16, W, Gen24 with smart meter)
                    Positive = import, Negative = export
   Register 40493 → Battery SOC         (Gen24 Plus only, 0–100%)
   Register 40495 → Battery power       (Gen24 Plus only, int16, W)

4. Fronius smart meter must be installed and paired
   for grid power register 40225 to report correctly

Lógica de prioridad de autoconsumo

Trigger condition: GA 9/0/1 (Grid Power) < −1000W
  → surplus export greater than 1 kW

Priority sequence (activate in order, release in reverse):
  1. Heat pump SG Ready (State 3 encouraged mode)
     → KNX binary output → heat pump S1/S2 terminals
  2. EV charger current increase (via EVCC/OCPP)
     → increase from 6A minimum toward surplus limit
  3. Immersion heater ON
     → KNX binary output → 3kW immersion contactor

Deactivation: GA 9/0/1 > −200W (export below 200W)
  → release loads in reverse priority order
  → 60-second hysteresis to prevent rapid cycling

Condiciones de autoconsumo con conocimiento de la batería

GA 9/1/0 (Battery SOC) conditions:

  SOC < 20%:
    → Pause all controllable loads
    → Prioritise battery charging from PV
    → SG Ready → State 2 (normal, don't add extra heat pump load)

  SOC > 80% AND GA 9/0/1 (Grid Power) < −500W:
    → Activate controllable loads (battery sufficiently full)
    → Standard priority sequence applies

  Battery power (GA 9/1/1):
    → Negative = battery charging (absorbing PV surplus)
    → Positive = battery discharging (supplying building)
    → Use to calculate net PV available for controllable loads:
       Available = PV power − battery charging power

Configuración SMA Sunny Boy Modbus TCP

Enable in SMA webserver:
  Settings > External communication > Modbus > ON
  TCP port: 502

Key registers (read-only, unit ID 3):
  30775 → AC power output   (uint32, W, 2 registers)
  30517 → Daily yield       (uint32, Wh, 2 registers)
  30513 → Total yield       (uint32, kWh × 1000)
  30521 → Operating status  (uint32, enum)

Note: SMA registers are uint32 (2×16-bit), big-endian.
Configure IN701KNX signal type as 32-bit unsigned integer.
SMA does not provide a signed grid power register without
a separate SMA Energy Meter — add SMA Energy Meter for
grid flow monitoring (registers 30865/30867 on Meter unit ID).

Fórmulas KPI para Gira X1 o IP-Symcon

Self-consumed power (W):
  = PV power (GA 9/0/0) − max(0, −Grid power (GA 9/0/1))
  (PV output minus what is being exported)

Self-consumption rate (%):
  = Self-consumed power / PV power × 100
  Target: > 70% with EV + heat pump controllable loads

Self-sufficiency rate (%):
  = Self-consumed power / Total building demand × 100
  Total demand = PV power − grid export + grid import
               = GA 9/0/0 + max(0, GA 9/0/1)

Annual self-consumption: log daily GA 9/0/2 (Energy today Wh)
  → accumulate in IP-Symcon variable → annual total kWh
  → self-consumption rate = annual self-consumed / annual yield

API de Solar.web vs Modbus TCP local

Solar.web REST API (api.solarweb.com):
  Latency: 1–5 minutes (cloud polling cycle)
  Use for: BREEAM energy reports, historical analysis,
           CSV export for energy assessors
  Poll: daily at 23:59 from IP-Symcon or ARISTO BewO
  Output: daily/monthly kWh → CSV → energy assessor

Local Modbus TCP (Fronius register 40070/40225):
  Latency: < 1 second (direct LAN poll at 10s interval)
  Use for: ALL real-time self-consumption control
           SG Ready triggers, EV current adjustment,
           export limiting, immersion heater switching

NEVER use cloud API for real-time control —
  1–5 minute latency makes load shifting ineffective

Secuencia de prueba de puesta en marcha

1. PV data verification (by 10:00 on a sunny day):
   ETS6 Group Monitor → watch GA 9/0/0
   → confirms PV Power W > 0 and rising with irradiance
   → compare with Fronius webserver display (should agree ±2%)

2. Grid flow verification:
   GA 9/0/1 should be negative when PV > building consumption
   GA 9/0/1 should be positive when PV < building consumption
   Turn off major loads, re-check sign changes

3. SG Ready functional test (without waiting for solar surplus):
   ETS6 Group Monitor → write −4000 to GA 9/0/1 (simulate export)
   → confirm Logic Module condition fires (GA 9/0/1 < −1000)
   → confirm SG Ready relay activates (State 3: S1=0, S2=1)
   → confirm with heat pump display (mode indicator changes)
   → restore: write 0 to GA 9/0/1 → relay deactivates

4. Battery SOC check (Gen24 Plus):
   GA 9/1/0 value should match Fronius webserver battery SOC %

5. Export limit test:
   Write 50 to power limit register via Group Monitor write
   → confirm Fronius webserver shows 50% power limit active