See your electricity as money
Every circuit in your home, costed by your own tariff — on a hub you own.
RBgrid shows what each circuit costs right now, today and this month — on your own tariff zones — stored on a small box in your fuse board. No account, no cloud, no subscription, no ads.
Free for personal, non-commercial use — source-available.
What you need
- An ESP32-WROVER board (PSRAM, 16 MB flash) — one you have, or any you buy; you flash it once over USB.
- One or more rbAmp measurement modules (up to eight per hub), clip-on sensors included or your own SCT-013 clamps.
- Modules from $3.99 (one channel) + $2.50 per extra channel. RBgrid itself is free for personal, non-commercial use — the hardware is the only cost.
Pick your way in
- I want it to just workFlash the release image or build from source, install the web app, run the setup wizard, see your first costs in the app. No code to write.
- I run Home AssistantThe hub announces every point over MQTT; HA creates the sensors itself. A ready table for the Energy dashboard.
- I want to build it my wayFull firmware source, ESP-IDF build, REST, WebSocket and MQTT APIs with a published schema.
What the app shows you
The quantities your tariff is built from — zones, rates, per-kWh taxes and VAT — computed on your own numbers.
- Cost right now per line and for the whole house, in your currency
- Today and month to date — energy and cost, with yesterday for comparison
- Which tariff zone you are in and when the cheaper one starts
- Where the money goes — share of today's cost by line
- Import and export measured separately, exported energy valued at your own rates
- History from hourly to yearly, on the hub's flash, downloadable as CSV
Tariff depth
The tariff engine is the heart of RBgrid — time-of-use with named zone types (night, morning peak, day, evening peak, late evening, weekend), plus per-kWh energy tax, grid fee and renewable levy, and VAT — all entered separately and all included in costs, applying your own rates. Export is valued at a per-zone sell price. It runs on the device, and the tariff code is in the source you can read and build (free for personal and non-commercial use).
demo.rbgrid.io
Try it with a home like yours
The full app with sample data — no hardware needed. Switch between setups:
How it fits together
rbAmp modules clip onto your existing wiring and measure each circuit. An ESP32-WROVER hub reads them over I²C, applies your tariff, keeps the history and serves the app — all on your home network.
How it differs
Unlike most plug-in monitors: your real tariff (zones, weekends, VAT), up to 12 points with history on one hub, history kept on the device, keeps measuring and storing with the internet down.
Unlike a Home Assistant build: no server to run — and if you do run HA, the hub plugs into it.
Licence
- RBgrid
RBgrid firmware is source-available under the PolyForm Noncommercial 1.0.0 licence — free to use, modify and build for personal and non-commercial use.
Commercial use requires a licence — contact info@rbamp.com. This is not an OSI "open source" licence.
- rbAmp
The rbAmp measurement libraries are a separate product under the MIT licence.
Built on rbAmp modules
Measurement comes from rbAmp I²C modules — a separate product. The ESP32 hub collects, computes and stores; the rbAmp modules are the supported measurement path.
RBgrid is developed by the rbAmp team; module sales fund the work. The firmware carries no ads and no telemetry to us.