Home Assistant Green: what it is and how to set it up

Home Assistant Green is the easiest way to start running Home Assistant. It is a small fanless box, designed by Nabu Casa and engineered by Seeed Studio, that arrives with Home Assistant OS already installed. You connect it to your router, plug in the power, and finish the setup in a browser. There is no imaging an SD card, no choosing an install method, no assembly.

Three things get conflated constantly, so it is worth separating them once. Home Assistant is free, open-source software. Green is a piece of hardware with that software preinstalled. Home Assistant Cloud is a separate paid subscription you do not need in order to use either. Get those three straight and most of the confusion around this product disappears.

The specification, and what it means in practice

In the box you get the hub, a Gigabit Ethernet cable, a 12 V DC 1 A power supply and a quick start guide that carries the warranty information. One thing that is not included and is easy to miss: the real-time clock battery. Green takes an optional CR2032, and it does not ship with one. It runs perfectly well without it, but fitting one means the clock survives a power cut.

It has no radios. That is the thing to understand first

Green has no wireless radios of any kind. No Zigbee, no Thread, no Z-Wave, and no Wi-Fi or Bluetooth either. This is the single most common misunderstanding about the product, and it is the one that ends in a return, because "everything you need in one box" reads as "it will talk to my sensors". It will not, until you add the radio yourself. Which adapter you need is its own decision, covered in our guide to choosing a radio adapter, but the short version is one adapter per protocol.

Ethernet only, and it needs the internet to finish setting up

There is one Gigabit Ethernet port and no Wi-Fi hardware, so Green has to reach your router or switch by cable. A USB Wi-Fi dongle is not the intended path, and the sensible advice is to leave the thing that runs your house on a wired connection anyway.

The part that catches people is the second requirement. Green needs working internet access the first time it starts, not just a local network, because it fetches updates and checks versions as part of onboarding. If your network blocks NTP, or blocks version.home-assistant.io, github.com or ghcr.io, setup stalls in a way that reads exactly like a dead unit. It is worth knowing that before you conclude the hardware is faulty.

Storage and memory are fixed

The 32 GB of eMMC is part of the board and there is no M.2 slot, so there is nothing to upgrade or swap. The microSD slot is not the escape hatch it looks like: it exists for recovery and re-imaging, not for storage or booting. Memory is fixed at 4 GB in the same way.

If you do run short, the supported route on Home Assistant OS is to attach an external data disk, a USB SSD or hard drive, and move the data onto it. Green keeps booting from its internal eMMC either way, and the external disk has to be larger than the internal one. Two practical notes: on a Green that disk hangs off USB 2.0, which caps throughput, and a USB SSD can draw real power from a shared 2 A budget across both ports, so a powered hub is worth considering.

Before you buy a disk, though, check what is actually filling the storage. Our advice is to look at the recorder database first: Home Assistant records every state change by default, and the settings to purge it, repack it, exclude noisy entities and shorten how many days you keep are all there. Most "my Green is running out of space" and "my Green feels slow" complaints turn out to be a multi-gigabyte history, and that costs nothing to fix.

Power over Ethernet

Green has no PoE. Its only power input is the 12 V DC barrel jack. Home Assistant Yellow was the model with native PoE, and it is now out of production. If you want Green running off a PoE switch, the way to do it is an external PoE splitter that outputs 12 V DC into a 5.5 by 2.1 mm barrel plug, and splitters are sold specifically for this. Nabu Casa has also said there is no PoE version of the ZBT-2 planned, so do not wait for one.

Matter, and what it actually gives you

Home Assistant is a Matter controller, which means it can commission and control Matter devices directly. On a Green, Matter devices on Wi-Fi or Ethernet need no extra radio: you install the Matter Server app and go. Matter over Thread is different, because Thread needs a border router in the house, and Green cannot be one without a Thread-flashed adapter attached.

Two limits worth knowing. Home Assistant is a controller, not a bridge, so it cannot turn the devices already inside it into Matter devices for Apple Home or Google Home. It can share a Matter device it commissioned itself with another platform, which is a different thing. And Matter only ever exposes a device's standardised features, so where a brand has a proper local integration in Home Assistant, that integration will usually give you more than Matter does.

Setting it up

You need an Ethernet connection to your network with working internet access, a power point, and a phone or computer with a browser. The hardware part genuinely does take minutes.

What discovery finds, and what it does not

This is where expectations and reality part company, so here it is plainly. Home Assistant discovers devices it can reach over your network. That is televisions, some appliances, printers, media players, anything speaking a protocol it recognises on the LAN. It does not discover anything on a radio it does not have. Your Zigbee sensors, your Z-Wave lock and your Bluetooth thermometer will be invisible until the matching adapter is plugged in and set up.

Beyond that, some brands need their integration added and an account signed into, and a few need a community integration installed through HACS. Those sit outside Home Assistant core and are maintained by their own authors rather than by the project, which is worth knowing before you build something important on one. The hardware is plug-and-play. Building out a house full of devices and automations is a project, and it rewards reading the documentation rather than expecting a one-tap setup.

Worth setting expectations on support too. Home Assistant is an open-source project, and the help it offers is community help: a forum, Discord and Reddit, with no phone line and no service commitment. Nabu Casa does run a knowledge base and a support form for its own hardware and for Cloud.

When you will outgrow it

Green's ceiling is set by four things that cannot change: the quad-core Cortex-A55, 4 GB of RAM, 32 GB of soldered storage, and USB 2.0 for anything you attach. For a normal mix of lights, sensors, switches and automations, none of those is a problem, and plenty of people never move past it.

Four workloads do push past it. Camera object detection, which is processor-hungry and writes constantly. Running a stack of other self-hosted services alongside Home Assistant. Fully local speech-to-text, where the project's own guidance is that Whisper wants at least an Intel N100-class processor, which Green is not, so on a Green you are steered to the lighter Speech-to-Phrase model and its fixed set of home-control phrases. And very large histories, with long retention and a lot of high-frequency sensors.

The symptoms that genuinely mean you have outgrown it are sustained high processor and memory use during ordinary operation, and storage warnings that persist after you have already trimmed the database. If the database is untrimmed, fix that first. If you know from the outset that cameras or local voice are the plan, start with different hardware instead. Migrating later is a backup and a restore rather than a disaster, but it is still an afternoon you did not need to spend.

Who it suits

Buy a Green if you want a dedicated, silent, low-power appliance for Home Assistant and you would rather not assemble or tune anything. Add a ZBT-2 with it if you own or intend to own Zigbee devices, which most people do. Look at a mini PC instead if cameras, local voice or a pile of other services are part of the plan, because those are the workloads Green was not built for and the ones you cannot fix later with an upgrade.