Getting Started with Home Assistant and Aqara
Every device I'd bought answered to a different company's servers. Home Assistant is how I pulled that back in, running on a second hand mini PC that costs less than one of the switches it controls.
The thing that pushed me into this wasn’t a feature I wanted. It was noticing that the front door lock, the doorbell, the ACs and the lights all answered to somebody else’s servers, and that a company I’d never spoken to could change what my house does with a firmware push. That’s a strange thing to sign up for without thinking about it, and I’d signed up for it about eight times over.
So the plan became: keep the Aqara hardware, because I’d already decided that part and I still think it’s right, but put something in the middle that I own. That something is Home Assistant, and this is what the setup actually looks like rather than what the marketing says.
What it runs on
A Lenovo mini PC. 7th gen i5, 8GB of RAM, a pair of 2TB SSDs. Six hours from plugging it in to the first build I’d call stable.
That’s a genuinely old machine and it’s completely fine, which is the useful bit of information here. Home Assistant is not demanding.
People buy a Raspberry Pi for this and then fight SD card corruption for a year, when a used office mini PC is cheaper, faster, has proper storage, and sits in a cupboard drawing almost nothing. If you’re about to buy a Pi, buy someone’s old Lenovo or Dell instead.
The other half is the Aqara Hub M3, which does the Zigbee coordinating. A lot of guides will tell you to buy a USB Zigbee stick and run the coordinator inside Home Assistant, and that’s a reasonable path. I didn’t, because the M3 also does Thread and Matter and takes PoE, so it sits on a network drop and does three jobs. That decision costs me something, and there’s a table further down where I pay for it.
What it’s actually for
The point isn’t dashboards. I barely look at the dashboard.
The point is that the logic lives on my hardware. 118 devices are onboarded as I write this, and when Home Assistant decides the corridor light should come on because the FP2 saw someone walk in, that decision happens on the mini PC in the cupboard, whether or not my internet is up. The slowest trigger in the house right now takes 1.2 seconds. The 20A switches on the water heater and the ACs are the ones I care most about here, because those are the automations where a cloud round trip and a “device unavailable” would actually matter.
It also means one place to look. Before this, checking why something didn’t fire meant opening whichever app owned that device and hoping it logged anything useful.
The part that isn’t clean
Here’s where I have to be honest about the local thing, because “fully local” is what everyone says and almost nobody means.
My setup has two brains. Home Assistant is one, the M3 is the other, and the Zigbee devices are really paired to the M3, with Home Assistant talking to it rather than owning them directly. That’s a dependency I chose. If Aqara changes how that integration behaves, I feel it. A plain Zigbee stick straight into Home Assistant would have avoided it entirely, and that’s the honest price of getting Thread, Matter and PoE in one box.
So the accurate version of my setup isn’t “local”. The automations are local, most of the devices are local, and a few important ones aren’t. Which is still a lot better than where I started, but it isn’t the clean story.
The other thing I’d flag is the 8GB of RAM. It isn’t a problem now. It’s the first thing I expect to hit as the device count climbs and the history database grows, and I’d rather say that now than pretend I’ve stress tested it.
Worth doing?
Definitely, and I’d have done it earlier. The mini PC cost less than one of the switches it controls.
What I’d tell myself six hours earlier
- Skip the Raspberry Pi. A used mini PC is cheaper, faster and won’t corrupt an SD card at 3am. This is the easiest decision on the list.
- Decide early where the coordinator lives. Both paths work. A hub buys you Thread and Matter and costs you a dependency, and it’s much more annoying to change later.
- Don’t bother making it pretty at first. I spent time on dashboards I now never open. The automations are the product.
- Work out which automations would actually hurt with the internet down, and make those genuinely local. The rest matters much less than the forums suggest.
Who the house answers to
The lock, the doorbell, the ACs and the lights used to answer to four different companies. Those companies still exist, and their firmware still updates. But the decisions about what this house does now happen on a second hand mini PC in a cupboard, and the only person who can change what it decides is standing in the house.