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 board with PSRAM and 16 MB flash — an ESP32-WROVER, or an ESP32-S3 on the N16R8 module. Both sizes matter, and on a WROVER 16 MB with PSRAM is the less common variant, so check a board you already have before you count on it. 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.
Solar in, export out — both counted, both priced
If your home exports, the numbers get harder: what you drew from the grid, what you fed back, and what each was worth under your tariff. RBgrid measures import and export separately at the supply point, keeps a generation point for your inverter, and values export at your own per-zone sell price — so the Economics screen shows produced, used and exported energy next to what it cost and what it was worth.
- Import and export — counted separately at the supply, hour by hour
- Generation — what the inverter produced, how much you used yourself, how much went out
What you need for it: an STD-UI1 on the supply — it counts both directions — and one channel on the inverter output. Three-phase supply: an STD-U3I3. See the parts and the price
RBgrid measures and accounts. It does not control the inverter, the battery or any load.
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).
Schedules and market day-ahead prices, both applied on the device.
Market prices in, your contract on top — and the price it used is kept
If your contract follows the market, a cost worked out at an average price was never your cost. RBgrid fetches the day-ahead price for your zone itself, applies your contract to it — markup, energy tax, grid fee, VAT — and prices each 15-minute period at that period's own price. It keeps the price it applied beside the energy, with the source of each period, for 40 days: a figure you can trace back rather than take on trust.
demo.rbgrid.io
Try it with a home like yours
Five setups built step by step: what to fit, how to set it up, and what the app shows. Each one opens in the live demo too — sample data, no hardware needed.
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Where the money goes in a flat on a day/night tariff
Build the RBgrid demo flat on a real hub - an STD-UI1 meter on the supply, five circuits on a Basic module, a day/night tariff - and what the app shows.
Open the live demo -
What the heat pump and the EV cost, per phase and per zone
See what the heat pump and the EV charger cost per phase and per tariff zone, on an STD-U3I3 meter and one Basic module per phase.
Open the live demo -
What your exported kWh is worth, hour by hour
Build the RBgrid demo solar house on a real hub - STD-UI1 meters on the supply and the inverter, circuits on a Basic UI5, export at your sell price.
Open the live demo -
Which machine is costing you — and how close the workshop is to its limit
Know which machine runs, what the compressor costs and how close the workshop is to its input limit: STD-U3I3 on the input, a Basic per phase.
Open the live demo -
Three chargers on one connection: what each costs, and how close to the limit
Build the RBgrid demo car park on a real hub - an STD-UI1 precise energy meter on the supply, three chargers on a Basic UI5, the Charging stations view.
Open the live demo
Home Assistant, step by step
Three guides that build one working setup, in order: every circuit into Home Assistant, your supplier's tariff on the hub, then a heat pump that follows it.
- A power meter for Home Assistant, from flashing to the Energy dashboardFlash RBgrid on an ESP32, clamp one circuit, and get power and energy into the Home Assistant Energy dashboard over MQTT discovery, with no templates.
- Your supplier's day and night prices, applied to every circuitEnter your time-of-use zones, per-kWh charges and VAT in RBgrid, and see what each circuit costs at the price of the zone its energy was used in.
- Your heat pump on its own line: what it costs, then automate in HAMeasure a heat pump on its own circuit, see what it costs at your day and night prices, then drive its setpoint from the hub's tariff zone in HA.
How it fits together
rbAmp modules clip onto your existing wiring and measure each circuit. An ESP32 hub reads them over I²C, applies your tariff, keeps the history and serves the app — all on your home network. Where a circuit is out of cable's reach, a second ESP32 measures there and sends its readings to the hub over its own radio link.
The circuits that aren't in the cabinet — measured too
A house rarely keeps its circuits in one board. A sub-panel in the garage, a workshop at the end of the garden, an annexe with its own supply: running a measurement cable to each of them is the reason most of a building never gets measured at all. A second ESP32 measures there instead, carrying its own modules and sending its readings to the hub over its own radio link — no cable back, and it never joins your Wi-Fi.
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.
No server to run — and if you already run Home Assistant, the hub can plug into it over MQTT, or run inside it as an ESPHome device.
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.