A new piece of software has taken charge at home: Home Assistant, the open-source project for home automation. Its appeal comes down to two words: local and vendor-neutral. Everything runs inside our own four walls, nothing depends on some provider’s cloud — and devices from very different manufacturers suddenly talk to each other. That the whole thing ended up rather more thorough than planned was, let’s say, foreseeable.
The architecture: professional habits included
You can take the architect out of the business project, but not the business project out of the architect. So Home Assistant does not run on a hobby board in a cupboard here — it runs as a virtual machine on a small Hyper-V host and is continuously mirrored to a second mini PC via Hyper-V Replica. If the hardware fails, the complete installation starts on the other machine within minutes. On top come the everyday perks of any VM: a snapshot before every update, and a migration is just a copy. Home Assistant additionally backs up its entire configuration to the Synology NAS automatically. From the road, an encrypted tunnel of our own leads into the house (WireGuard) — no cloud subscription required. Do you need all this for light switches? No. Does it put your mind at ease? Enormously.
Zigbee: the devices you already own simply move in with you
The point that matters most to us, because it so often gets lost: Zigbee is an open radio standard. The bulbs, plugs and sensors that hang off some manufacturer’s hub today are not chained to it. In our house, the Philips Hue bulbs had been talking to the built-in Zigbee hub of our Amazon Echo devices for years; “Alexa, lights on” was the most-spoken sentence under this roof. The migration was a deliberate decision with a one-time price: briefly reset every device and pair it again with our own network — a coordinator with an Ethernet port instead of a USB stick, with the Zigbee2MQTT software on top. Since then: nothing new to buy, no app required, one system instead of three isolated islands. If you already own Zigbee devices, half of your smart home is already in the house.
And because trust is good but redundancy is better, at some point the question landed on the table whether you can run two Zigbee coordinators in failover mode. That this question even comes up in a family smart home probably says more about me than about the technology. (The answer: Zigbee knows no true failover — but a backup of the coordinator, network keys included, turns the spare into a cold-start twin, without a single device having to be paired again.)
The voice stays — it just lives here now
“Lights on”, by the way, still works by voice. Only now the command is picked up by the Home Assistant project’s official voice hardware: wake word “Okay Nabu”, a German speech pipeline, evaluated entirely locally. Not a word leaves the house, no account is listening in. It is a strangely good feeling that voice control would keep working even if the internet went down. (The default wake word is just a placeholder, by the way — a custom one is already in the works.)
The automations: this is where the fun starts
It begins with small things — lights and scenes, a message to your phone when something needs attention. None of it justifies the effort on its own; together it quickly feels as if the house had grown a nervous system.
More than convenience: smoke detectors and a camera with a mind of its own
It gets really interesting where convenience turns into safety. The smart smoke detectors are connected locally through their base station and report centrally to Home Assistant: if one of them triggers, the whole house knows — and so does the phone, whether anyone is at home or not. On the side, the system keeps an eye on the battery level and reachability of every single detector, instead of leaving that to the occasional beep in the stairwell.
The new Reolink camera brings its own AI along: it detects right on the device whether a person, a vehicle or an animal is moving through the picture — the analysis happens inside the camera, no footage has to travel to a cloud for it. In Home Assistant these detections arrive as plain sensors and can be wired to anything: notifications, lights, recording. And the recordings stay in the house like everything else: the video streams go to the NAS, not to some vendor’s subscription storage. Everyday AI does not have to be spectacular — sometimes it is simply the difference between “something is moving” (a branch in the wind) and “a person is standing at the door”.
The highlight: the car charges when it makes sense
The automation that made it all worthwhile is the charging control. Three ingredients, all local: the solar storage system continuously reports via Modbus TCP what the roof delivers, what the house consumes and whether the battery is charging or discharging — the manufacturer’s app would rather route all this through its cloud, but on the local network the device simply speaks Modbus. The wallbox can be granted or denied charging permission over the same protocol. And Home Assistant sits in between and decides according to the mode: Off, PV (charge only the surplus from the roof), Price (charge when the dynamic electricity tariff is cheap) or Manual. The thresholds are sliders on the dashboard, and a watchdog cleans up if a sensor ever stops answering.
A lesson learned along the way: to an electric car, an enabled wallbox is not an option but an invitation — ours simply starts charging. The permission is the control. Since then, the car prefers to charge when the sun delivers or electricity is cheap, and nobody has to think about it anymore.
At the end of the day, this is the same work as in our client projects: getting systems from different vendors to talk to each other, with clean interfaces, monitoring and a plan B. Except that this time the client is my own family — the most demanding client of all.