Full solar + grid balancing — including off-grid operation and while charging batteries.
K2 is the full solar-system kit. It builds on K1 by using an rbAmp UI2 module — line voltage plus two current channels — so the router sees both the grid and the solar feed from one sensing module. That unlocks OFFGRID — routing the load from measured solar generation with no grid connection — on top of the full grid-balancing set. It balances consumption and export across both feeds, during generation and while batteries charge.
What's in the box
- DimmerLink phase-cut dimmer — choose 16 A / 24 A / 40 A (≈ 3.7 / 5.5 / 9.2 kW at 230 V) with on-TRIAC temp sensor, heatsink, and active fan
- rbAmp UI2 measurement module — line voltage + 2 current channels (grid + solar roles, voltage-capable), factory-calibrated, with on-board I2C pull-ups (sufficient for a bus run under ~30 cm)
Not included: the CT clamps (no SCT-013 clamps in the kit — add one per current channel, grid + solar), ESP32 / ESP32-C2 host, cabling, enclosure, and power supply.
Modes unlocked
Adds OFFGRID to K1's set → the full range: OFF · MANUAL · BOOST · GRID_LIMIT · ECO · AUTO · OFFGRID. See Operating Modes and Overview §1.7.
Fully open source — source code & firmware on GitHub; pre-built binaries for ESP32, C2-HTTP, and C2-MQTT
Key features
- Dual-channel sensing from one rbAmp UI2 — grid and solar, factory-calibrated and galvanically isolated
- Everything K1 does (AUTO / ECO / GRID_LIMIT), plus OFFGRID
- OFFGRID — route from measured solar generation with no grid connection; backs off as generation falls
- Balances consumption and export during generation and while charging batteries
- Solar-aware routing sized to your system
- Runs on ESP32 / ESP32-C2; MQTT + Home Assistant, REST, OTA (ESP32)
Who it's for
Owners of full solar systems, including off-grid / hybrid setups with batteries, who want maximum self-consumption and complete grid+solar balancing.
What you'll also need
- Two clamp-on CTs (grid + solar; SCT-013 series or compatible — not included)
- ESP32 / ESP32-C2 host (not included), a 3.3 V supply, I2C cabling, and an enclosure
- Solar PV generation and an AC-mains resistive load; WiFi
- For OFFGRID: size the resistive load to your system (the mode tracks solar, not battery state of charge)
Specifications
| Parameter | Value |
|---|---|
| Dimmer | DimmerLink phase-cut (I2C), 16 / 24 / 40 A, active thermal management |
| rbAmp | UI2 — line voltage + 2 current channels (grid + solar, voltage-capable) |
| CT (clamp-on) | Not included — 2× SCT-013 series or compatible (grid + solar) |
| Measurement | Grid signed power + solar generation; PF, frequency |
| Calibration | Factory-calibrated; select CT model per channel |
| Bus pull-ups | On-board on rbAmp (adequate for I2C run < ~30 cm) |
| Isolation | rbAmp galvanically isolated |
| Operating modes | Full set incl. OFFGRID (7 modes) |
| Host | ESP32 / ESP32-C2 — not included |
| Bus | I2C (all modules on a shared bus) |
| Connectivity | WiFi · REST · MQTT / Home Assistant · OTA (ESP32) |
| Firmware | Open source (ESP32 & ESP32-C2 builds) |