# SolBus Ahaon – Resol VBus WiFi Board (ESP32-C3)

All-in-one Resol VBus to WiFi board — reads your DeltaSol solar controller into Home Assistant via ESPHome. On-board ESP32-C3, USB-C.

- **Seller:** [Solbus](https://lectronz.com/stores/solbus), Dublin, Ireland
- **Price:** €70.00 (EUR, before shipping and taxes)
- **Availability:** In stock
- **Categories:** ESP32, Home automation, WiFi
- **Country of origin:** China
- **HS code:** 847330
- **Product page:** https://lectronz.com/products/solbus-ahaon-resol-vbus-wifi-board

## Links

- [Documentation](https://esphome.io/components/vbus.html)

## Images

![SolBus Ahaon – Resol VBus WiFi Board (ESP32-C3)](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzcxNjcsInB1ciI6ImJsb2JfaWQifX0=--4e3e082fab343da876eb7609bd04991146842bd9/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/Ahaon_V2_angle_final.jpg)
![SolBus Ahaon – Resol VBus WiFi Board (ESP32-C3)](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzcxNzEsInB1ciI6ImJsb2JfaWQifX0=--9675628355a73735e781747a0fa5bf7cf3d8e207/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/Ahaon_V2_top_final.jpg)
![SolBus Ahaon – Resol VBus WiFi Board (ESP32-C3)](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NzY4NzAsInB1ciI6ImJsb2JfaWQifX0=--9468192ae389432ab527977da53b5689eeceb610/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJwbmciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--605f1da017bcbb03ce31845cd0e81d97e3b3c574/2026-10-28T12-06-30.644Z-HA_solar_card_tindie.png)

## Description

## SolBus Ahaon — Resol VBus to WiFi Board (ESP32-C3)

*SolBus Ahaon — 'a haon', Irish for one — the all-in-one board, designed in Ireland.*

**Get your solar thermal system into Home Assistant with one small board.** SolBus Ahaon reads live data from your Resol / DeltaSol solar controller over VBus and sends it to Home Assistant via ESPHome. The ESP32-C3 is built in, so there's no separate ESP to wire up and no jumper leads. Connect two wires, plug in USB-C, and you're logging.

### What's new in V2
- **Works with the standard ESPHome VBus config.** The VBus signal is now corrected in hardware, so you use a plain `rx_pin: GPIO3` with no `inverted: true` workaround. The example configs from the ESPHome VBus docs work as written.
- **Power / status LED on from the start.** The LED lights as soon as the board gets power, even before it's flashed, so you can see at a glance that it's alive. Once ESPHome is running, it works as a proper status light and blinks if something goes wrong.
- **Marked "v2" on the board**, so you always know which version you have.

### What you see in Home Assistant
- Collector, tank and return temperatures (all Pt1000 sensor readings)
- Pump / relay status and speed
- Operating hours, heat quantity and system status, where your controller reports them

### Features
- **All-in-one:** VBus front-end and ESP32-C3-MINI-1 on a single board
- **Native USB-C:** power and flashing over the same cable, no USB-serial adapter needed
- **Screw terminal** for the two VBus wires, so no soldering is required
- **BOOT / RST buttons** for easy flashing and recovery
- **Status LED:** on at power-up, controlled by ESPHome for status and error indication
- **ESPHome ready:** works with ESPHome's built-in VBus component
- **Read-only:** it listens to VBus and never writes to your controller

### Compatibility
Works with **any Resol VBus controller**. If your controller has VBus terminals (often 9/10), this board will read it. That includes the rebadged versions: **Resol, DeltaSol, Viessmann (Vitosolic), Firebird, COSMO, Caleffi (iSolar), Sonnenkraft, Kingspan, Joule, Citrin Solar, De Dietrich, Wagner, Kioto, Apricus, Thermann, Dux.**

- **Native ESPHome models** (just select the model): DeltaSol BS Plus, BS 2009, BS/2 (DrainBack), C, CS, CS2, CS4, CS Plus.
- **Other models** such as the BS/4, BS/2 HE, E and SLL are read fine by the hardware but need a short custom ESPHome config. If you have a BS/2 HE, I can send you my working config on request.

Not sure about your controller? Message me before ordering with the model name or a photo of the label, and I'll tell you straight whether it's supported.

### What's in the box
- 1× SolBus Ahaon board (model **VBUS-C3-V2**)

You supply a USB-C cable, a 5V USB power adapter, and two wires to your controller's VBus terminals.

### Specifications
- **MCU:** ESP32-C3-MINI-1 (WiFi 2.4 GHz)
- **Power:** 5V via USB-C
- **VBus input:** 2-pin screw terminal, receive-only, on GPIO3
- **Status LED:** GPIO10 (via MOSFET, on by default)
- **Front-end:** 1N4148 bridge with LM339 comparator. The VBus and ESP share a ground reference, which is standard for a receive-only tap on a low-voltage SELV bus.

### About this board
SolBus Ahaon is an open-hardware **developer board** for Home Assistant and ESPHome users. It's built on the open-source VBus community work, with credit to the original authors.

**Safety:** Power only from a 5V USB supply. Connect only to low-voltage VBus data terminals, never to mains or relay outputs. For indoor, dry use. At end of life, dispose of as electronic waste (WEEE).

**Manufacturer:** SolBus, Dublin, Ireland. solbus.ireland@gmail.com

*RESOL and VBus are trademarks of RESOL – Elektronische Regelungen GmbH. SolBus is not affiliated with RESOL.*

## Shipping policy

Orders ship from Dublin, Ireland via An Post, usually within 1–2 working days. Standard Post is untracked.

Typical delivery times: Ireland 1–3 days, UK and EU 1–2 weeks, Canada/Australia/NZ 2–3 weeks.

EU and Northern Ireland orders have no customs charges. Orders to Great Britain and outside the EU are sent with a customs declaration.