What you need, and what it costs
RBgrid is free firmware for personal, non-commercial use. The cost is the measurement hardware: rbAmp modules — plus an ESP32-WROVER board you already have or buy anywhere.
- You bring: an ESP32-WROVER board (PSRAM, 16 MB flash) and the ability to flash it over USB. You buy: one to three rbAmp modules, with or without sensors.
- Basic SCT-013 modules from $3.99 (one channel) + $2.50 per extra, use your own clamps. STD energy meters: STD-UI1 (1-phase) $19.90, STD-U3I3 (3-phase) $59.90. CT-kit modules (matched clamps) are in validation. Prices are rbAmp's recommended retail — current prices on rbamp.com.
- Clamp around the live conductor only, arrow toward the load
- Voltage reference through a fuse
- Module to board: four wires (I²C)
- Board powered from USB
- Wi-Fi to your home network.
Where to buy
RBgrid runs on rbAmp measurement modules. Buy them from the maker, or from our storefront on AliExpress. Not sure which modules you need yet — keep reading: the sets below are sized by how many circuits you want to measure.
How the modules connect to the hub
Every rbAmp module talks to the ESP32 board over the same four wires. There is no board per circuit and no wiring per GPIO: the eighth module connects exactly like the first, because they all share one I²C bus.
- Four wires per module: VIN to the board's 5 V/VIN (not 3.3 V), GND, SDA to GPIO25, SCL to GPIO26. The board itself is powered over USB.
- One bus, many modules. One hub drives up to 8 modules — up to 56 current channels — and keeps history for 12 measurement points.
- Each module answers at its own address. They ship at the same one, so connect and readdress them one at a time; the first module sits at 0x50.
- Keep each cable to 15 cm. With up to three modules leave the modules' pull-ups exactly as they are — no cutting, no extra resistors. From the fourth module on, cut them on all but one.
Pinout, the readdressing steps and the wiring diagram: our Quick start and the rbAmp wiring guide.
Typical setups
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Flat
1 × STD-UI1 (precise supply meter) + 1 × Basic 5-ch
CT kit: in validation
Modules ship with the same address — readdress them one at a time before connecting both; see the rbAmp wiring guide.
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House, single-phase, heat pump + EV
1 × STD-UI1 + 1 × Basic 7-ch
CT kit: in validation
Modules ship with the same address — readdress them one at a time before connecting both; see the rbAmp wiring guide.
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House, three-phase, heat pump + EV
1 × STD-U3I3 + 3 × Basic UI3 (one per phase)
CT kit: in validation
Laundry and lights are left unmetered in this set. Modules ship with the same address — readdress them one at a time before connecting both; see the rbAmp wiring guide.
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House that exports (input + inverter)
1 × STD-UI1 (input) + 1 × STD-UI1 (inverter) + 1 × Basic 5-ch (UI5)
CT kit: in validation
Modules ship with the same address — readdress them one at a time before connecting both; see the rbAmp wiring guide. Leave each module's pull-ups as they are: an RBgrid hub with up to three modules on cables up to 15 cm needs no jumper cutting and no extra resistors.
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Workshop, three-phase
1 × STD-U3I3 + 1 × Basic UI1 (L1) + 2 × Basic UI3 (L2, L3)
CT kit: in validation
Modules ship with the same address — readdress them one at a time before connecting both; see the rbAmp wiring guide.
Module prices only, in USD; boards and sensors are extra. Current totals and delivery are on rbamp.com.
Build your set on rbamp.com
rbAmp's configurator asks what you want to measure, how many phases and circuits you have, and whether you already own SCT-013 clamps — and returns a parts list, an assembly sheet and a quote. Pick "rbgrid on an ESP32" as the data destination and the set is RBgrid-ready.
Supported modules
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STD meters
On-board energy counters for the grid input — single-phase STD-UI1 or three-phase STD-U3I3, each with its calibrated current sensors included — see the box contents on rbamp.com.
STD-UI1 $19.90 / STD-U3I3 $59.90
Accuracy figures are each module's own specification — see rbamp.com.
Have solar? The STD meter on the supply counts both directions; add an STD-UI1 on the inverter output (bound as a generation point) and you get produced, used and exported.
Which module do I need?
Most home setups start with the Basic AC wattmeter for an SCT-013 clamp. See the full Basic range and its specs on rbamp.com.
The hub is your ESP32-WROVER
An ESP32-WROVER board with PSRAM and 16 MB flash. Flash the release image over USB (esptool) or build from source, then install the web app from the release. After that the hub can be updated over the air — you upload a new image from the web app.
From rbamp.com
The maker's store — full module range and documentation.
Basic AC wattmeter (SCT-013, UI series)
Shop the AC wattmeter modulerbamp.comBasic ampere meter (SCT-013)
Shop the AC ammeter modulerbamp.com
Our official RobotDyn store, if you prefer AliExpress. RobotDyn Official Store
RBgrid is developed by the rbAmp team; module sales fund the work.
For any work inside an electrical panel, call a qualified electrician. The rbAmp modules clip onto existing wiring.
Common questions
Does it fit my fuse board?
The rbAmp modules sit on a DIN rail by your breakers; the clamps go around existing wires — nothing is cut. Any ESP32-WROVER board with PSRAM and 16 MB flash fits. Work inside the board is for a qualified electrician.
Split-phase (US/Canada)?
No. RBgrid measures single-phase and three-phase supplies; split-phase — two live legs sharing a neutral — is not covered.
Can I start with one module and add more?
Yes — up to 8 rbAmp modules on one hub (up to 56 current channels), added from the app, with history for up to 12 measurement points.
What if rbAmp stops?
The hub runs without any server, and the RBgrid hub firmware source plus the MIT module libraries are published — you keep what you have.
Do I need a special shield?
No. Any ESP32-WROVER board with PSRAM and 16 MB flash works; you flash it once over USB.
I already have SCT-013 clamps — do they work?
Yes, if they are the voltage-output models — 1 V at rated current: SCT-013-005, -010, -020, -030, -050, -060 and -100. The current-output SCT-013-000 (50 mA) is not supported. On modules with clamp-on CT inputs you pick the clamp model per channel in the app. (The CT-kit modules ship with matched clamps instead.)
I have solar panels — what do I need?
An STD-UI1 on the supply (an STD-U3I3 for three phases), so import and export are counted separately, and an STD-UI1 on the inverter output as the generation point (or a Basic channel with a voltage reference on the same phase). The app then shows produced, self-used and exported energy and values export at your per-zone sell price.