Wendy is an open-source Deno Fresh dashboard for off-grid renewable energy systems. It polls Morningstar TriStar MPPT and Victron GX hardware via Modbus TCP at 1 Hz, stores samples in SQLite, and streams live charts over SSE — running on a Raspberry Pi 5. Originally built to monitor an experimental twin axial-flux wind turbine with dual 24V/48V battery banks and solar panels powering a Chia blockchain full node.
The Chia node (Raspberry Pi 5) and a mobile router are powered via a Linovision 5-port PoE switch with dual 24V/48V redundant input — 24V primary to use all wind yield directly without going through the battery. Wendy replaces Home Assistant with a focused, real-time monitoring interface for the energy system and optionally the Chia node status.
Collects data from Victron Energy and Morningstar hardware via Modbus TCP, stores 7 days of full-resolution history in SQLite plus up to a year of compressed daily archives (wendy-archive.db, gzipped columnar blobs, ~250 MB/year), and serves a live dashboard via Deno Fresh. Includes a transparent overlay mode (/overlay) for compositing real-time stats and charts over a live video stream using headless Chrome and ffmpeg. Supports split deployment: the Pi collects hardware data and forwards it over WebSocket to a VPS that runs the dashboard.
- Deno 2.x / Fresh 2 / TypeScript — server and UI, single binary runtime
- SQLite (
@db/sqlite) — hot window + compressed daily archive - Modbus TCP — TriStar MPPT 600V and Victron GX (BMV-700, SmartShunt)
- Server-Sent Events — live dashboard updates
- Docker — bundled
Dockerfileanddocker-compose.yml - Optional: headless Chromium + ffmpeg for the video overlay mode, Windy.com Point Forecast API for wind forecast panel
Wendy uses two identical axial flux generators that can be switched between parallel (24V) and series (48V) configuration based on wind conditions. The system has three data sources, all polled via Modbus TCP at 1-second intervals:
- Morningstar TriStar MPPT 600V (48V charge controller) — array voltage, battery voltage, current, temperature, charge state. Registers use IEEE 754 half-precision (float16) encoding.
- Victron Wind Control BMV-700 (24V shunt) — voltage, current, power, charged energy. Polled via Victron GX Modbus TCP gateway (unit 239,
com.victronenergy.battery). - Victron Wind Turbine SmartShunt (48V shunt) — voltage, current, power, produced energy. Polled via GX gateway (unit 223,
com.victronenergy.dcsource).
MQTT is used only for the GX keepalive (keeps the GX publishing data for Modbus reads).
Single-page 2x2 grid layout fitting one viewport:
┌──────────────┬──────────────┐
│ Hero stats │ Power chart │
│ (watts, V, │ (total, │
│ kWh, temp) │ 24V, 48V) │
├──────────────┼──────────────┤
│ Voltage │ Current │
│ (array, │ (24V shunt, │
│ bat 48/24) │ 48V shunt) │
├──────────────┴──────────────┤
│ Voltage — 24h history │
├─────────────────────────────┤
│ Wind forecast (Windy.com) │
│ -6h ← now → +42h │
└─────────────────────────────┘
- Real-time streaming charts (canvas, 10-minute window, 1s resolution)
- 24h voltage history chart at the bottom
- Wind forecast strip powered by the Windy.com Point Forecast API — 6h history + 42h ahead, color-coded wind speed/gust values and direction arrows
- Live SSE updates for all values
- Dynamic Y-axis scaling
- Light/dark theme (follows system preference, overridable)
- 24V/48V mode detection with hysteresis
The dashboard includes a wind forecast strip powered by the Windy.com Point Forecast API. Thanks to Windy.com for providing an excellent weather data API.
The forecast is fetched server-side once per hour — coordinates never reach the browser. The API returns GFS model data with wind u/v components and gust values, which are converted to speed, gust, and meteorological direction. The dashboard displays a columnar strip spanning 6 hours of history through 42 hours ahead, with color-coded wind speed and gust values, direction arrows, and the current time column highlighted.
Set WENDY_WINDY_API_KEY, WENDY_WINDY_LAT, and WENDY_WINDY_LON to enable. The forecast strip is hidden when these are not configured.
A dedicated page for compositing over a live video stream (headless Chrome + ffmpeg). Transparent background, semi-transparent dark panels, large fonts, thick chart lines.
┌─────────────────┬─────────────────┐
│ │ WENDY · 24V │
│ (transparent) │ 1,247 W │
│ video shows │ 52.4V / 54.1V │
│ through │ 0.42 kWh today │
│ │ 34°C · mppt │
├─────────────────┼─────────────────┤
│ Voltage chart │ Power chart │
│ (array, 48V, │ (total, 24V, │
│ 24V battery) │ 48V output) │
└─────────────────┴─────────────────┘
- Transparent background for headless Chrome compositing
- 3px chart lines, 14-16px fonts for video readability
- Semi-transparent dark panels (
rgba(0,0,0,0.6)) - No interactive elements
The system can run in three modes controlled by WENDY_ROLE:
Everything in one process — the original all-in-one mode for running on the Pi:
Docker Container
┌────────────────────────────────────────────┐
│ ┌──────────┐ ┌──────────┐ ┌─────────┐ │
│ │ TriStar │ │ Victron │ │ Fresh │ │
│ │ Modbus │ │ GX Modbus│ │ Server │ │
│ └────┬─────┘ └────┬─────┘ └────┬─────┘ │
│ └──────┬───────┘ │ │
│ ▼ │ │
│ ┌───────────────────┐ │ │
│ │ DataBus │─── SSE ────►│ │
│ │ (event hub + │ │ │
│ │ ring buffer) │ │ │
│ └────────┬──────────┘ │ │
│ ▼ │ │
│ ┌───────────────────┐ │ │
│ │ SQLite │◄─── REST ───┘ │
│ └───────────────────┘ │
│ ┌──────────┐ │
│ │ MQTT │ GX keepalive │
│ └──────────┘ │
└────────────────────────────────────────────┘
The Pi collects hardware data and forwards it over WebSocket to the VPS, which runs the dashboard:
Pi (source) VPS (display)
┌─────────────────────┐ ┌─────────────────────────────┐
│ TriStar Modbus │ │ /api/ingest (WebSocket) │
│ Victron Modbus │── Reading ─►│ │ │
│ Victron MQTT │ over WS │ ▼ │
│ │ │ │ DataBus │
│ ▼ │ │ ├── SSE → clients │
│ DataBus │ │ ├── flush → SQLite │
│ │ │ │ └── ring buffer │
│ ▼ │ │ │
│ ws-client ──────┼─────────────┼──► Fresh server │
│ (bearer token) │ HTTPS/WS │ (dashboard, REST API) │
└─────────────────────┘ └─────────────────────────────┘
DataBus is the central event hub. Pollers push readings into it. It detects 24V/48V mode from the array voltage (hysteresis at 48V/52V thresholds), maintains a 10-minute ring buffer for chart preloading, broadcasts merged state to SSE subscribers, and buffers samples for batched SQLite writes every 5 seconds.
git clone git@github.com:janit/wendy.git
cd wendy
cp .env.example .env
./scripts/deploy.shThe deploy script builds the Docker image, runs a smoke test, deploys with --network host for LAN access, and prunes old images/containers. SQLite data persists in ./data/.
Generate a shared secret and set it on both sides:
openssl rand -hex 32Pi (data source):
# .env
WENDY_ROLE=source
WENDY_UPSTREAM=ws://your-vps:8086/api/ingest
WENDY_SECRET=your-shared-secret
WENDY_MQTT_HOST=192.168.47.6
WENDY_MODBUS_HOST=192.168.47.11
WENDY_GX_HOST=192.168.47.6./scripts/deploy.sh # needs --network host for Modbus/MQTTVPS (dashboard):
# .env
WENDY_ROLE=display
WENDY_PORT=8086
WENDY_SECRET=your-shared-secret./scripts/deploy.shNo --network host needed on the VPS. A Caddyfile.example is included for putting Caddy in front of the dashboard. The Pi connects directly to port 8086 with a bearer token — use a VPN, firewall rules, or Caddy with TLS to secure the connection in transit.
All config via environment variables (see .env.example):
| Variable | Default | Description |
|---|---|---|
WENDY_ROLE |
standalone |
source, display, or standalone |
WENDY_UPSTREAM |
— | WebSocket URL for source mode (e.g. ws://your-vps:8086/api/ingest) |
WENDY_SECRET |
— | Shared secret for WebSocket auth (must match on source + display) |
WENDY_MQTT_HOST |
192.168.47.6 |
Victron GX MQTT broker (source/standalone) |
WENDY_MQTT_PORT |
1883 |
MQTT port |
WENDY_MODBUS_HOST |
192.168.47.11 |
TriStar 600V Modbus TCP (source/standalone) |
WENDY_MODBUS_PORT |
502 |
Modbus port |
WENDY_GX_HOST |
192.168.47.6 |
Victron GX Modbus TCP (source/standalone) |
WENDY_GX_MODBUS_PORT |
502 |
GX Modbus port |
WENDY_DB_PATH |
./data/wendy.db |
SQLite database path (display/standalone) |
WENDY_PORT |
8086 |
HTTP server port (display/standalone) |
WENDY_WINDY_API_KEY |
— | Windy.com Point Forecast API key (display/standalone) |
WENDY_WINDY_LAT |
— | Latitude for wind forecast |
WENDY_WINDY_LON |
— | Longitude for wind forecast |
deno task dev # Vite dev server with HMR
deno task build # Build for production
deno task serve # Production server with data collection
deno task test # Run testswendy/
├── main.ts # Fresh app export (Vite entry)
├── serve.ts # Production entry: boot + serve built app
├── lib/
│ ├── boot.ts # Startup: role-based init (source/display/standalone)
│ ├── databus.ts # Event hub, mode detection, ring buffer, SSE broadcast
│ ├── modbus.ts # TriStar MPPT 600V Modbus TCP poller
│ ├── victron-modbus.ts # Victron GX Modbus TCP (24V + 48V shunts)
│ ├── mqtt.ts # Victron MQTT (GX keepalive only)
│ ├── ws-client.ts # WebSocket client (source mode → upstream VPS)
│ ├── types.ts # Wire types for WebSocket messages
│ ├── db.ts # SQLite schema, batched writes, queries
│ ├── windy.ts # Windy.com Point Forecast API poller (hourly)
│ ├── float16.ts # IEEE 754 half-precision decoder
│ └── state.ts # Shared state (globalThis bridge for bundled routes)
├── routes/
│ ├── index.tsx # Dashboard (2x2 grid + 24h chart)
│ ├── overlay.tsx # Stream overlay (transparent, for video compositing)
│ └── api/
│ ├── events.ts # SSE stream of live merged readings
│ ├── ingest.ts # WebSocket endpoint (display mode, receives from Pi)
│ ├── recent.ts # Ring buffer (last 10 min) for chart preload
│ ├── history.ts # 24h samples from SQLite
│ ├── forecast.ts # Wind forecast JSON (from Windy.com cache)
│ ├── stats.ts # Daily aggregates
│ └── health.ts # Health check (includes version hash)
├── islands/
│ ├── StreamingCharts.tsx # Canvas charts (power, voltage, current, 24h)
│ ├── OverlayCharts.tsx # Overlay charts (voltage + power, thick lines)
│ ├── WindForecast.tsx # Wind forecast strip (Windy.com data)
│ └── ThemeToggle.tsx # Light/dark switch
└── scripts/
├── deploy.sh # Build, smoke test, deploy, prune
└── scan-modbus.py # Diagnostic: scan GX Modbus unit IDs
- wendy-curves — companion power-curve tuning tool for the TriStar MPPT controller. Consumes Wendy's live SSE stream, keeps its own long-term archive, and helps you find a better voltage→watts curve by scoring candidates against the empirical p90 envelope of observed samples.
MIT