Keeps your electricity capacity tariff in check by watching live power draw (from InfluxDB) and shedding/restoring large consumers (via Home Assistant) whenever the current 15-minute billing block is projected to exceed a target.

How it works

Belgian-style capacity tariffs bill on the highest 15-minute average power of the month. Every CONTROL_LOOP_INTERVAL_MS (default 10s), the app:

Reads recent power samples for the current quarter-hour block from InfluxDB.
Projects what that block's final average will be if current draw continues.
If the projection exceeds TARGET_KW, it sheds the lowest-priority configured device (turns a switch off, or lowers a number set-point to its floor) via Home Assistant.
Once the projection is comfortably back under target, it restores the highest-priority shed device.

A minimum dwell time per device (configurable) prevents rapid on/off cycling. Devices with "manual override" enabled are left alone by the control loop.

Setup

Copy .env.example to .env and fill in your InfluxDB and Home Assistant connection details, the measurement/field that holds live power, and your target kW.
docker compose up --build
Open http://localhost:3000, go to the Devices tab, and add your EV charger, heat pump, and any other large consumers with their Home Assistant entity IDs, control type (switch or number), and priority (lower priority number = shed first).

Local development

npm install
npm run dev:backend   # Fastify API on :3000
npm run dev:frontend  # Vite dev server on :5173, proxies /api to :3000
npm test               # backend unit tests (quarter-hour projection, control decisions)

Architecture

backend/src/influx — queries live power samples from InfluxDB (Flux).
backend/src/control/quarterHour.ts — pure logic computing the running and projected average power for the current 15-minute block.
backend/src/control/loop.ts — pure decision logic: which device to shed or restore given the projection and device states.
backend/src/control/runner.ts — orchestrates the above against real InfluxDB/Home Assistant/SQLite on each tick.
backend/src/homeassistant — Home Assistant REST client and device shed/restore abstraction.
backend/src/db — SQLite config store (devices, target, action log, block history).
frontend/ — React dashboard: live status, device list, 30-day peak history chart, recent actions log, and a Devices config page.