Self-hosted app that replays your actual ESB Networks half-hourly smart-meter data against a library of Irish electricity tariff plans and ranks them by true annual cost — including solar export credit, standing charges and time-of-use bands (day/night/peak/EV/free windows).
Comparison sites take your annual kWh and apply a "typical" usage profile. But with a smart meter, solar panels, and time-of-use tariffs, when you use electricity matters more than how much — a plan with a cheap night rate is brilliant for one house and useless for the next.
What a comparison site does: asks for your annual kWh (or guesses), applies a one-size-fits-all usage curve, ignores your solar export, and prices maybe a dozen headline offers on the day you visit.
What this app does: replays your actual last 365 days — all 17,500 half-hour meter readings — through every plan's real rate bands, credits your export at each plan's own microgeneration rate, includes standing charges and signup credits, and re-checks supplier rate cards monthly. The ranking is your house's ranking, not an average household's — and it can honestly tell you that staying put is the best deal, which no commission-funded comparison site will. It also links with Home Assistant to push a phone notification 30 and 7 days before your current contract expires — the ranking lands in front of you exactly when switching is penalty-free.
The Usage tab shows where your kWh actually land across the day (the case for a night tariff at a glance) and monthly import/export; the Plans tab manages suppliers, rate bands and time windows:
The Settings tab holds your current plan and contract dates (for the expiry alerts), the optional Home Assistant connection for notifications, and the manual HDF upload:
- A nightly job copies the HDF interval export (
esbn_hdf_latest.csv) intodata/and POSTs/api/ingest. The file comes from my fork of the esbn-to-mqtt Home Assistant add-on, which saves a local copy of each HDF download (to/share/esbn/) alongside publishing the MQTT sensors — the stock add-on doesn't keep the file. Any other source of an ESB Networks HDF export works too: download it manually from your ESB online account and upload it straight from the dashboard. - The costing engine assigns each half-hour to a plan's rate band by local clock time and weekday (interval START time), sums import costs, subtracts export credit, adds the standing charge and annualises.
- Plans and their rate bands are managed in the UI (
/plans); seed data for the six main suppliers is inapp/seed.pywith an as-of date — rates are entered including VAT. - Contract-expiry alerts fire at 30 and 7 days via a Home Assistant notify service (
/settings). - A monthly scrape-and-suggest job keeps the rates honest — see below.
Irish suppliers have no rates API, so app/scraper.py checks the per-supplier rate cards on
selectra.ie (one structured page
per supplier) monthly, and diffs what it finds against your stored plans. Design choices:
- Suggest, never auto-apply. Differences are queued as suggestions on the Plans page with per-item Apply/Dismiss and an Apply-all. A parsing glitch can't silently corrupt the ranking you'll make a switching decision on. Applying a suggestion also bumps the plan's "rates as of" date.
- Fail loudly. If a page fetch fails or parses to zero plans (layout change), you get a Home Assistant notification rather than quietly stale rates — same channel as when it finds genuine changes.
- Sticky dismissals. A dismissed value won't be re-suggested; a further change to that rate will be.
- What it reads: urban unit rates per band (converted to include 9% VAT — Selectra quotes ex-VAT), standing charge, microgeneration export rate. Plans it sees but you don't track surface as informational suggestions.
- What it can't read: band time windows (peak hours, EV boost windows) aren't published in the rate tables — verify those against the supplier's own terms when adding a plan.
Trigger it manually with the Scrape rates now button on the Plans page (or
curl -X POST localhost:8000/api/scrape), or on a schedule (this
deployment uses a systemd timer on the 1st of the month). Worth knowing: on its very first run
it caught a seeding error in this repo — a rate copied from the rural column instead of urban —
so the review queue earns its keep.
Pre-built images (amd64 + arm64) are published to Docker Hub and GHCR:
docker run -d --name tariff-optimiser -p 8000:8000 \
-v ./data:/data --restart unless-stopped \
colfin22/tariff-optimiser:latest
(or ghcr.io/colfin22/tariff-optimiser:latest). To build from source instead:
docker compose up -d --build
Supplier plans seed themselves on first boot. Then upload your ESB Networks
HDF file on the Settings page (or drop it at data/esbn_hdf_latest.csv
and curl -X POST localhost:8000/api/ingest if you're automating). /health
reports readiness — plan count, readings count, newest reading — and tells
you what's missing on a fresh install.
Running outside Docker? Python 3.12+ required (the image handles it for you).
Re-seed plans after editing them: docker compose exec tariff python -m app.seed --force.
python -m pytest tests/
Built by Colm Finn — MIT licensed.