Standalone PV surplus charging controller for go-e Gemini wallboxes with Sungrow inverters. Runs independently of Home Assistant — but coexists peacefully alongside it.
There are excellent Home Assistant integrations for both Sungrow and go-e. This controller takes a different approach:
- Direct hardware access — Modbus TCP to the inverter, HTTP to the wallbox
- No MQTT, no YAML automations, no template sensors
- Shorter control chain → less latency, fewer failure points
- Runs alongside HA — your existing sungrow-bridge / HA setup remains untouched
This isn't a "better HA." It's a dedicated tool for one job: pushing PV surplus into your car with precision.
┌──────────────────┐ Modbus TCP ┌──────────────────┐
│ Sungrow SH8.0RT │ ◄──────────────────► │ │
│ (WR1 + WR2) │ │ go-e PV │
└──────────────────┘ │ Controller │
│ (Python) │
┌──────────────────┐ HTTP API │ │
│ go-e Gemini V4 │ ◄──────────────────► │ Port 8088 │
│ (Wallbox) │ │ Dashboard │
└──────────────────┘ └──────────────────┘
│
┌───────┴───────┐
│ history.json │
│ simulator.log │
│ config.yaml │
└───────────────┘
- PV-driven amp selection —
pGrid / (230V × phases)yields the optimal charging current - Automatic phase switching 1-phase ↔ 3-phase with hysteresis
- Safe transitions — amp=0 → switch phases → new amp (protects the go-e)
- 5-minute cooldown between phase switches to prevent cloud-induced flapping
- 500 W deadband — ignores minor fluctuations
- Grid-import guard — pGrid=0 whenever power is drawn from the grid
- Live values: PV, grid, battery, house load, wallbox, pGrid
- Decision matrix — all 9 charging stages at a glance
- 1-hour chart (survives controller restarts)
- Scrollable decision log with error tracking
- Toggleable logging via button
- Auto-refresh every 2 seconds via WebSocket
- Modbus fallback: holds last valid readings on timeout
- No PID windup, no lingering integrals
- Rotating log (max 4 MB), writes only on state changes
- systemd user service with auto-restart
| Component | Model | Connection |
|---|---|---|
| WR1 | Sungrow SH8.0RT | Modbus TCP 192.168.178.151:502 |
| WR2 | Sungrow (secondary) | Modbus TCP 192.168.178.154:502 |
| Wallbox | go-e Gemini V4, FW 60.5 | HTTP API 192.168.178.200 |
| Host | Raspberry Pi 4B, Debian 13 | — |
Different hardware? The controller uses Sungrow Modbus registers (13007, 13009, 13021, 5016). For other inverters, adjust the register addresses in
controller.py. The go-e HTTP control works with all Gemini models.
git clone https://github.com/tobwil/goe-pv-controller.git
cd goe-pv-controller
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txtEdit config.yaml:
goe:
ip: "192.168.178.200" # Your go-e IP
max_amps: 12 # Hardware limit
min_amps: 6 # Below 6A, no car will charge
min_power_w: 1380 # 6A × 230V (1-phase minimum)
phase_switch:
hysteresis_up: 4500 # Switch 1→3 phase above this
hysteresis_down: 3200 # Switch 3→1 phase below this
min_switch_interval: 300 # 5 min cooldown
deadband:
amps: 3 # Only change if Δ ≥ 3A
watts: 500 # Only change if Δ ≥ 500W
simulation:
enabled: false # false = LIVE control, true = log only
log_file: "/path/to/simulator.log"
history:
file: "/path/to/history.json"
web:
host: "0.0.0.0"
port: 8088mkdir -p ~/.config/systemd/user
cp pv-wallbox-controller.service ~/.config/systemd/user/
# Adjust paths in the service file:
# WorkingDirectory=/path/to/goe-pv-controller
# ExecStart=/path/to/goe-pv-controller/venv/bin/python .../web_ui.py
systemctl --user daemon-reload
systemctl --user enable --now pv-wallbox-controller
# Check status
systemctl --user status pv-wallbox-controllerAvailable at http://<host>:8088
Five cards display PV production, grid feed-in/draw, battery charge/discharge, house consumption, and wallbox load. The pGrid value is the available surplus — the control variable.
| pGrid | Phase | Amps | Charging Power |
|---|---|---|---|
| 0 – 1,379 W | — | 0 A | 🛑 STOP |
| 1,380 – 1,839 W | 1ph | 6 A | ~1,380 W |
| 1,840 – 2,299 W | 1ph | 8 A | ~1,840 W |
| 2,300 – 2,759 W | 1ph | 10 A | ~2,300 W |
| 2,760 – 4,499 W | 1ph | 12 A | ~2,760 W |
| 4,500 – 5,519 W | 3ph | 6 A | ~4,140 W |
| 5,520 – 6,899 W | 3ph | 8 A | ~5,520 W |
| 6,900 – 8,279 W | 3ph | 10 A | ~6,900 W |
| ≥ 8,280 W | 3ph | 12 A | ~8,280 W |
Phase switching uses hysteresis: upshift at 4,500 W, downshift at 3,200 W. Between these thresholds, the current phase is held — no flip-flopping on cloudy days.
The 1-hour chart shows pGrid, PV, target amps, and actual amps. Below it, the decision log captures timeouts, connection errors, and switching decisions.
| Endpoint | Method | Description |
|---|---|---|
/ |
GET | Dashboard HTML |
/api/state |
GET | JSON: sensors, decision, history, logs |
/api/toggle_log |
POST | Toggle logging on/off |
/ws |
WebSocket | Live push (every 2s) |
pGrid is the available surplus for the wallbox, in watts. The formula accounts for battery charging and grid import:
If battery charging: pGrid = grid_feedin + wallbox_load
If battery discharging: pGrid = grid_feedin + wallbox_load − battery_discharge
If grid importing (< −50W): pGrid = 0 (no surplus available)
This ensures the wallbox runs on 100% PV surplus — no grid draw, no battery drain.
Switching phases under load can damage the go-e. The controller handles this safely:
- amp=0 → wallbox stops charging
- 0.5s pause → go-e processes the stop
- psm=X → set phase mode (1=1ph, 2=3ph)
- amp=Y → set new amperage
The entire sequence takes under 1 second and only occurs every ≥5 minutes.
The controller runs independently but doesn't interfere with HA:
- sungrow-bridge stays untouched — HA continues receiving PV data
- go-e integration in HA keeps running — you see charging status as usual
- The controller only reads (Modbus → inverter) and writes to the go-e (amp, psm)
- No MQTT topic overlap, no duplicate sensors
You can run this controller without touching your HA setup at all.
| Symptom | Cause | Solution |
|---|---|---|
| Controller stops immediately (pGrid=0) | No PV surplus or grid import | Normal during clouds/night |
| "Connection reset by peer" in log | Brief Modbus disconnect | Harmless — controller uses fallback values |
| TimeoutError | Inverter or go-e temporarily unreachable | Controller retries next cycle automatically |
| Dashboard shows empty chart | Controller restarted, no history.json yet | Fills up within 1h — history persists every 30s |
| go-e not charging despite surplus | alw=False in go-e API |
Enable charging permission in go-e app |
| Phase switching flutters | Hysteresis too tight | Widen hysteresis_up/down in config |
├── controller.py # Core: Modbus, go-e API, control logic, phase switching
├── web_ui.py # FastAPI: dashboard + API endpoints
├── config.yaml # Configuration (IPs, thresholds)
├── requirements.txt # Python dependencies
├── pv-wallbox-controller.service # systemd user unit
├── templates/
│ └── dashboard.html # Live dashboard with Chart.js
├── dashboard.png # README screenshot
├── history.json # Auto-generated: chart data (survives restarts)
└── simulator.log # Decision log (rotating, max 4 MB)
- MQTT status push (optional, for HA integration if desired)
- Config UI in dashboard
- Docker container
- Support for additional inverters (GoodWe, Fronius, Solax)
MIT