Home Assistant is an open-source platform that pulls every smart device in your home under one roof and runs the logic locally, on your own hardware, without a vendor cloud. It is the answer to ecosystem sprawl: one brain instead of a Hue app, an Apple Home app, a Tesla app, and five others that do not talk to each other. It keeps working when the internet drops, and it does not phone your data home. This is my running journey note: I have now bought the Home Assistant Green hub and the Home Assistant Voice Preview Edition, and I will keep this updated as the system grows.
What it does
- 1,500+ integrations with smart-home devices and services, most working locally.
- Automations with conditional triggers, an event engine, and Jinja2 templating.
- Dashboards you build per room or per purpose.
- Energy management that unifies solar, battery, grid, and per-device consumption.
- Assist, a local voice assistant, plus companion iOS/Android apps with presence detection.
- Matter and Thread support, and Zigbee/Z-Wave via USB radios.
- Runs on a €179 fanless box drawing about 2 watts.
It is a project of the non-profit Open Home Foundation, which by charter cannot be sold or acquired. Around 2 million households run it.
For business people
The problem it solves is fragmentation. Every smart device ships its own app and its own cloud, and they rarely cooperate. Home Assistant sits underneath all of them and gives you one place to see and control everything, plus automations that cross brands ("when the last phone leaves home, lights off, thermostat down, doors locked").
Two things make it different from Apple Home, Google, or SmartThings:
- Local and private. The logic runs on a box in your house. No subscription is required to use it, and your presence and sensor data stay local. If your internet or a vendor's cloud goes down, your home still works.
- It cannot be taken away. It is run by a non-profit funded by hardware sales and an optional cloud subscription, not by a company that can pivot, get acquired, or kill the product.
Cost shape: the software is free. A Home Assistant Green hub is a one-time $199 / €179. Home Assistant Cloud is an optional $6.50/month for remote access, cloud voice, and Alexa/Google links, and it funds the project.
The honest limitation: it is yours to run. That means an afternoon of setup, occasional maintenance, and tolerance for tinkering. If you want zero-effort and only own Apple gear, Apple Home is simpler. If you want one system that owns every device, deep automations, and energy insight, Home Assistant is the ceiling.
For technical people
Install flavours:
| Flavour | What it is | Use when |
|---|---|---|
| HA OS | Full appliance image (Core + Supervisor + add-ons) | The default. Green, Yellow, a mini PC, a Pi, or a VM |
| Supervised | HA-managed stack on your own Debian | You want HA to manage add-ons on existing Linux |
| Container | Just the Core container (Docker) | You run your own Docker host and skip add-ons |
| Core | Python venv, no Supervisor | Advanced, manual, no add-on ecosystem |
HA OS gives you the Supervisor and the add-on store, where each add-on is a managed Docker container: Mosquitto (MQTT broker), Node-RED (visual flows), ESPHome (firmware for ESP32 DIY sensors), Studio Code Server (browser YAML editor), and Samba/backup.
Integrations are added through the UI config flow or YAML. Automations live in YAML or the visual editor, with scripts, scenes, and templates. The recorder logs state to SQLite by default; swap to MariaDB plus InfluxDB and Grafana if you want long-term, queryable energy history. There is a REST and WebSocket API with long-lived access tokens, which is the hook for pushing data in and pulling state out from your own Python. Releases ship monthly, calendar-versioned (e.g. 2026.7); back up before updating.
The hardware I bought
Home Assistant Green
The plug-and-play entry hub: HA OS pre-installed, fanless, connect Ethernet and power and you are running in about 15 minutes. Designed by Nabu Casa, engineered by Seeed Studio.
| Spec | Detail |
|---|---|
| SoC | Rockchip RK3566, quad-core Arm Cortex-A55 |
| CPU | 1.8 GHz |
| Memory | 4 GB LPDDR4X |
| Storage | 32 GB eMMC |
| Networking | Gigabit Ethernet |
| USB | 2x USB 2.0 Type-A (for Zigbee/Z-Wave/Thread sticks) |
| Power | 12 V DC, ~1.7 W idle / ~3 W load |
| Size / weight | 112 x 112 x 32 mm, 340 g |
| Price | 199 USD / 179 EUR |
The one real limitation: 32 GB of non-expandable eMMC. Fine for most homes, but heavy camera or long-history logging setups will want external USB storage or a more powerful box later.
Home Assistant Voice Preview Edition
A local, privacy-first voice assistant in a small box. It is a client, not a server: it needs a running Home Assistant instance (the Green) to do the thinking, and it can run the whole voice pipeline locally or offload to Home Assistant Cloud.
| Spec | Detail |
|---|---|
| Size | 84 x 84 x 21 mm |
| Audio in | Dual far-field microphones + XMOS audio chip (noise handling) |
| Audio out | Integrated speaker, plus 3.5 mm jack with dedicated DAC for hi-fi streaming |
| Controls | Rotary volume dial, button, physical mute switch, LED ring |
| Wake words | "Okay Nabu" (default), "Hey Jarvis", "Hey Mycroft", or custom |
| Processing | Fully local (with capable hardware) or via Home Assistant Cloud |
| Price | 69 USD / 59 EUR |
Getting the Voice PE running
The phone-based onboarding is the easy path. What you need first:
- A running Home Assistant server (the Green), updated to the latest version, and a user with Administrator rights.
- Your 2.4 GHz Wi-Fi password (not 5 GHz; the Voice PE joins on 2.4 GHz, and some routers default to 5 GHz).
- The Home Assistant Companion app on your phone, logged in as an admin, with Bluetooth enabled (used only for onboarding).
Then: power on the Voice PE, open the Companion app, follow the Bluetooth onboarding to hand it your Wi-Fi, pick a wake word, and choose local or cloud speech processing under Assist. Full walkthrough:
How I am setting it up in my environment
My home already leans Apple (UniFi network, Apple TVs as HomeKit hubs, iPhone and Watch), with Philips Hue lighting and a Tesla Model 3, Powerwall 3, and solar. Home Assistant is the layer that ties the lighting, the network, and the energy system together and still hands control back to Siri.
Where it runs
The Green is the always-on hub: fanless, silent, about 2 W, sits on the shelf next to the NAS and just runs. Not the Mac Studio (it sleeps and reboots), not the UniFi UNAS Pro (storage only), not the old Synology DS413j (too weak). If I later want headroom for VMs and heavy add-ons, a mini PC (Intel N100) running HA OS is the upgrade path. Add a Connect ZBT-2 dongle only when I bring in Zigbee or Thread devices.
Network
Give it a static DHCP reservation on the UniFi network. If I isolate IoT on its own VLAN, enable mDNS reflection so discovery still works across VLANs. Add the UniFi Network integration for device tracking and presence detection off the router, which is more reliable than phone GPS alone.
Bridge it into Apple Home
Connect Home Assistant straight to the Hue Bridge (local Hue integration, faster than routing through Apple Home), then expose everything back out with the HomeKit Bridge integration so Siri and the Apple Watch keep controlling it. Add the Apple TV integration for media state and automations. Net result: HA is the brain, Apple Home stays the remote.
Energy: Powerwall 3, solar, and the Model 3
This is the feature that justifies the whole thing for me. The Energy Dashboard puts solar production, home consumption, grid import/export, and Powerwall charge in one view, then lets me automate on it: start Model 3 charging when solar surplus crosses a threshold, or hold charging for cheap-tariff hours. One caveat to check first: Powerwall 3 changed its local API compared with the older Backup Gateway, so I may need the Tesla Fleet API (cloud) or a community integration rather than pure local polling. Verify that before assuming a local-only setup.
Backups
Nightly HA backups to the Synology over Samba, plus one copy off-box. RAID keeps the NAS disks alive, but the HA config is the irreplaceable part, so it gets the same 3-2-1 treatment as my documents share (see RAID Types for a NAS).
Pricing
| Item | Cost | Notes |
|---|---|---|
| Home Assistant software | Free | open source, self-hosted |
| Home Assistant Green | $199 / €179 | one-time, fanless always-on hub |
| Home Assistant Cloud | $6.50/mo or $65/yr | remote access, cloud voice, Alexa/Google; funds the project |
| Voice Preview Edition | $69 / €59 | local voice puck |
| Connect ZBT-2 / ZWA-2 | ~$30-40 | Zigbee/Thread or Z-Wave radios |
Where to buy in Germany
For anyone following the same path, smartdomo is a German retailer specialised in Home Assistant hardware, with strong reviews (about 4.8/5 across Trustpilot and ausgezeichnet.org). Buying from an EU shop means an EU warranty, local returns, and no customs surprises. BerryBase is a second German option, and in the UK The Pi Hut ships across the EU.
- In the box (Green): the hub, a Gigabit Ethernet cable, a universal 12V/1A power supply with EU/US/UK adapters, and the quick-start guide.
- Stock: official hardware sells out in waves, so availability is the thing to watch. See ZBT-2 vs Sonoff Dongle Max for the ZBT-2 vs Sonoff Dongle Max coordinator comparison.
Setup checklist
- Power on the Home Assistant Green, reserve a static IP for it on the UniFi network.
- Onboard: set location, units, and an admin account; update to the latest version.
- Add integrations: Hue (via the bridge), HomeKit Bridge (expose to Apple Home), Apple TV, UniFi Network, Tesla/Powerwall.
- Onboard the Voice PE via the Companion app (Bluetooth), pick a wake word, choose local vs cloud speech.
- Build the Energy Dashboard with solar, grid, Powerwall, and car.
- Configure nightly backups to the Synology, plus an off-box copy.
- Optional: Home Assistant Cloud for remote access and Siri, ESPHome and Node-RED add-ons for DIY sensors and flows.
My take / journey notes
I went local-first on purpose: I want the smart home to keep working when a vendor's servers go down, and I do not want the data leaving the house. The Green + Voice PE combo was about 250 EUR to a private, voice-controlled starting point. First automations on the list: presence-based lighting, a morning routine, solar-aware car charging, and pulling the studio gear into scenes. This section is the running log; I will add radios, ESPHome sensors, and dashboards as I go.
Further Reading
