Category: Gear

For years, my answer to “which presence sensor should I buy?” came with an asterisk the size of a power brick. mmWave radar — the technology that can tell a sleeping human from an empty couch — was simply too hungry to run on batteries. If you wanted real presence detection instead of PIR motion blips, you accepted a USB cable snaking down your wall. In my house that meant exactly two rooms got proper presence detection, because those were the two rooms where I could hide the wire.

That constraint quietly died over the past year, and I don’t think enough people noticed. So today: a look at where presence sensing stands in mid-2026, what I’d actually put on my own walls, and the category of devices I’d still avoid even though they’re a third of the price.

The trick that made batteries viable

Quick recap for anyone who hasn’t fallen down this rabbit hole. PIR sensors detect changes in heat, which means they need actual movement. Sit still reading a book and your lights go out — the classic smart home embarrassment. mmWave radar detects micro-movements like breathing, so it knows you’re still there. The catch: radar transmits constantly, and constant transmission eats coin cells for breakfast.

The solution that finally shipped in current-generation hardware is almost annoyingly obvious: use both. A PIR sensor sips microamps and acts as the doorbell — the moment it sees motion, it wakes the mmWave radar, which takes over and holds presence until the room is genuinely empty. Then the radar goes back to sleep. The 60 GHz radar chip both Aqara and SwitchBot use in their latest battery sensors is built around exactly this duty-cycling idea, and it’s the reason we’re suddenly seeing multi-year battery claims on devices that would have lasted weeks before.

What I’d buy for battery-only spots

The Aqara FP300 is the one that’s been going in and out of stock since launch, and having read the teardowns and long-term reviews, I understand why. It packs the 60 GHz radar, a PIR trigger, plus light, temperature and humidity sensors into one puck running on two CR2450 cells, with a claimed battery life of up to three years. It speaks either Zigbee or Thread — you pick the firmware — and pairs with Zigbee2MQTT without any Aqara hub in sight, which is exactly how I like my devices: local, hub-free, and talking to the coordinator I already own.

One detail that matters if you’re deciding between the two radio modes: reviewers consistently report that the full set of configuration parameters is only exposed in Zigbee mode. The Thread/Matter firmware is far more limited. That tracks with my broader experience — Matter keeps promising the world and keeps shipping the lowest common denominator. For a Home Assistant household, Zigbee mode is the obvious choice, and it’s not close.

The SwitchBot Presence Sensor is the budget sibling worth knowing about: same radar chip, same PIR-wakes-radar principle, but powered by standard AAA batteries rated for up to two years. No environmental sensors, so it does one job — but AAAs are cheaper and easier to source than coin cells, and with fewer extras on board it may well outlast the FP300 in practice. If I were covering a hallway or a guest room where temperature data is irrelevant, this is where I’d save the money.

Where wires still win

Battery sensors answer “is someone in this room?” Wired sensors can answer “where exactly, and how many?” — and if you have power available, that’s still a meaningful upgrade.

The Aqara FP2 remains the zone-mapping king: up to 30 detection zones in a single room, each exposed as its own occupancy entity in Home Assistant. Desk occupied, couch occupied, dining table empty — three different automations from one device. The honest caveat: zone setup happens in the Aqara app. It’s a one-time thing and you can uninstall the app afterwards, but for a no-cloud purist it’s a compromise, and I’d rather tell you that up front than have you discover it during onboarding.

For the ESPHome crowd, Apollo Automation’s R PRO-1 is the interesting one — dual mmWave radars (an LD2412 and an LD2450) with Power-over-Ethernet, natively ESPHome so it’s fully local and endlessly tweakable. PoE on a presence sensor sounds like overkill until you remember that anyone running cameras already has a switch with spare ports. And if your budget says otherwise, the Sonoff SNZB-06P has quietly become the default cheap wired Zigbee option — nothing fancy, but it holds presence reliably.

The DIY corner

An ESP32 plus a Hi-Link LD2410B/C module is still the cheapest way into mmWave, and the ESPHome integration is mature to the point of boring — which is the highest compliment I can pay infrastructure. The newer LD2412 and LD2450 modules now have official ESPHome support too, with the LD2450 adding multi-target tracking for those who want FP2-style capability without the app. My own bare-metal Home Assistant box already runs the ESPHome add-on for other projects, so the marginal cost of one more DIY sensor is a few francs of hardware and an evening of fiddling. That evening is the fun part, if we’re honest.

What I’d still avoid

The flood of cheap Tuya-based Zigbee presence sensors on AliExpress and Amazon is still going strong, and my advice hasn’t changed: skip them. It’s not that they can’t detect presence — many do it fine. The problem is how they behave as network citizens. Several of the popular models spam the Zigbee network with constant status updates, and testers have found this essentially unfixable. A single chatty sensor can degrade a mesh that dozens of well-behaved devices depend on. Saving twenty francs on a sensor isn’t worth destabilizing the network your whole house runs on.

The bottom line

For the first time, my recommendation doesn’t depend on where your power outlets are. Battery mmWave is no longer a compromise — the FP300 in Zigbee mode is a genuinely complete presence sensor you can stick anywhere. Wires still buy you zones and multi-person tracking, and DIY still buys you the most capability per franc. The only losing move in 2026 is the bargain-bin Tuya puck that turns your Zigbee mesh into a shouting match.

Next on my list: replacing the PIR sensor in the office — the room where I sit stillest, longest, and get plunged into darkness most often. If the FP300 survives a Swiss winter of radiator-adjacent mounting, you’ll read about it here.

The Shelly 1 Gen4 and 1PM Mini Gen4 cover most of my in-wall switching, but readers keep asking the obvious follow-up: is there anything else out there? Specifically, is there a real alternative to the full-size Shelly 1PM Gen4 — the 16A relay with built-in power metering — from another manufacturer? I went looking. The short answer: yes, but almost nobody matches all of what the Shelly does at once.

Disclosure: some links on this page may become affiliate links. If you buy through them, I earn a small commission at no extra cost to you.

What you’re actually trying to replace

The reason the 1PM Gen4 is hard to beat isn’t any single spec — it’s the combination. In one wall-box-sized module you get 16A switching, real power and energy metering, no hub required (it exposes a local HTTP API and MQTT over Wi-Fi), and multiprotocol flexibility — Wi-Fi and Bluetooth out of the box, switchable to Zigbee or Matter. Most competitors nail two or three of those and quietly drop the rest. So the right alternative depends entirely on which of those four things you’re willing to give up.

The five alternatives worth knowing

1. Aqara Single Switch Module T1 — the closest true match

This is the most direct like-for-like: a Zigbee in-wall relay with genuine power and energy metering, in a similar compact size. If you already run Aqara or a solid Zigbee mesh, it does almost exactly what the Shelly does. The catch is that it’s Zigbee-only and happiest through an Aqara hub, so you lose the Shelly’s hub-free Wi-Fi independence and its protocol-switching trick.

2. Sonoff MINIR4 / MINIR4M — cheapest, but no metering

Sonoff is the usual price-fighter, and this is exactly where it stumbles. Its in-wall minis are excellent little relays — the MINIR4M even adds Matter — but they have no power metering at all. Sonoff’s energy-monitoring lives in its plugs and DIN-rail modules (POWR3, POW Elite), not in a wall-box relay. So Sonoff is only an “alternative” if you’re happy to drop the metering requirement to save money.

3. EVVR Energy Monitoring Relay — 16A metering with HomeKit

EVVR built this one specifically around accurate energy monitoring at a full 16A, with Matter and native HomeKit support. It’s a genuine 16A-plus-metering competitor and a strong pick if you live in the Apple Home world. Downsides: it’s pricier than the Shelly and has a larger footprint, so back-box space matters.

4. Tuya / MOES / Zemismart Zigbee relays — cheap and metered, if you’re brave

There’s a whole class of white-label Zigbee in-wall modules with power metering, sold under Tuya, MOES, Zemismart and others, often for very little money. In Zigbee2MQTT or ZHA they can work well. But build quality and firmware are inconsistent, and there’s no clean local Wi-Fi/HTTP API like Shelly’s — so treat them as a budget/tinkerer route, not a set-and-forget one.

5. Staying inside Shelly’s own range

Sometimes the best “alternative” is a different Shelly. The 2PM Gen4 gives you two metered channels at 16A each in one box — great where two loads sit together. And the DIN-rail Wave Pro 1PM covers the same 16A-with-metering job in a consumer-unit form factor. Same ecosystem, same app, no compromises on local control.

Quick comparison

Ratings vary by exact SKU and region — always check the specific model’s datasheet before wiring it to a real load.

So which should you buy?

If your requirement is the full set — in-wall, 16A, metered, hub-free, and multiprotocol — the Shelly 1PM Gen4 is genuinely still close to unique, and switching brands mostly means giving something up.

Pick Aqara’s T1 module if you’re already invested in Zigbee/Aqara and want the closest metered equivalent. Pick EVVR if you want 16A metering with proper HomeKit. Reach for Sonoff only when you can live without metering and just want cheap reliable switching. And go Tuya/MOES/Zemismart only if you enjoy the Zigbee2MQTT rabbit hole and want metering on a shoestring.

For my own house, the Shelly stays the default — but it’s healthy that the alternatives finally exist. Competition is how these things get cheaper.

If you’ve shopped Shelly’s Gen4 line recently you’ve probably hit the same wall I did: there are now four “Shelly 1” relays that all sound nearly identical. The two people ask me about most are the full-size Shelly 1 Gen4 and the tiny Shelly 1PM Mini Gen4. They look like the same product in two sizes — but they actually differ on three things at once, and picking the wrong one means either a relay that won’t fit your wall box or one that can’t carry your load. Here’s how I decide.

Disclosure: some links on this page may become affiliate links. If you buy through them, I earn a small commission at no extra cost to you.

Same family, three differences at once

The confusing part is that these two aren’t a clean “big vs small” pair. Going from the 1 Gen4 to the 1PM Mini Gen4 changes the size, the maximum current, and whether you get power metering — all in one step. So it helps to name what each letter and word in the product name actually does.

The “PM” means Power Metering: the device measures real-time voltage, current, wattage, and accumulated energy, and reports it to Home Assistant or the Shelly app. The plain 1 Gen4 has no metering at all — it only switches.

The “Mini” means the module physically shrinks to fit inside a crowded back box behind an existing switch or socket, at the cost of a lower current rating.

Shelly 1 Gen4: the full-size dry-contact workhorse

The Shelly 1 Gen4 is the one I reach for when something needs real switching capacity or galvanic isolation. Its relay is a potential-free (dry) contact rated to 16A, which means it doesn’t pass your mains through to the load — it just opens and closes a contact. That’s exactly what you want for switching a separate circuit, a boiler call-for-heat input, a garage door motor, an electric gate, or anything running on a different voltage than the module itself.

What it does not do is tell you how much power that load is drawing. There’s no energy reporting, because there’s no metering hardware inside. For a boiler relay or a gate, that’s fine — you rarely care about the wattage of a dry contact.

Shelly 1PM Mini Gen4: metering in a matchbox

The Shelly 1PM Mini Gen4 takes the opposite priorities. It’s small enough to disappear inside a junction box behind a light switch, and it adds the power metering the plain 1 lacks — so every light, fan, or appliance it controls becomes a live energy sensor in Home Assistant. The trade-off is capacity: it’s a switched output rated to 8A / ~2000W, not a 16A dry contact.

For the bulk of a smart home — ceiling lights, extractor fans, a desk-lamp circuit, under-cabinet LEDs — that’s plenty, and the per-device consumption data is genuinely useful for spotting a fan left running or building an energy dashboard.

Head to head

Don’t forget the other two in the grid

Because the difference is really two independent choices — size and metering — Shelly fills out the full 2×2 grid, and the other two corners are often the better answer:

If you want metering and 16A capacity, that’s the full-size Shelly 1PM Gen4. If you just need a small dry-contact switch with no metering, that’s the Shelly 1 Mini Gen4 (8A). Laying it out as a grid makes the choice obvious:

How they fit a Home Assistant setup

Both join Home Assistant the same way and share the Gen4 multiprotocol trick: out of the box they speak Wi-Fi and Bluetooth, and you can flip them to Zigbee or Matter from the button or app. If you’ve already set up a Thread/Zigbee border router like the ZBT-2, the Zigbee and Matter modes drop straight into that mesh. In Wi-Fi mode you also get MQTT, webhooks, and the local web UI, so automations keep running even if your HA server is down — the same independence that makes the Shelly Flood Gen4 such a strong fail-safe leak sensor.

The practical difference is what each one contributes to your dashboard. The 1PM Mini gives you a per-device power sensor for free — useful for energy automations like “tell me if the bathroom fan has been on for more than an hour,” and exactly the kind of tile worth surfacing when you’re building a clean Home Assistant dashboard. The plain 1 Gen4 gives you a clean, isolated switch entity and nothing else, which is exactly right when it’s wired to something like a boiler input where mixing voltages would be dangerous.

My rule of thumb

Reach for the Shelly 1 Gen4 when the job needs muscle or isolation: a high-current load, a separate circuit, or a dry-contact input on a boiler, gate, or garage motor. Metering would be wasted there anyway.

Reach for the Shelly 1PM Mini Gen4 when you’re retrofitting behind an existing switch and the load is light — lights and fans — and you want that circuit to double as an energy sensor. The small body is the whole point: it goes where the full module physically won’t.

And if you find yourself wanting both metering and 16A, or both small size and a dry contact, that’s your sign to look at the other two corners of the grid rather than forcing one of these two to do a job it wasn’t built for.

A small box from Nabu Casa landed on my desk this week: the Home Assistant Connect ZBT-2. It’s the official Home Assistant radio stick — successor to the SkyConnect/ZBT-1 — and it’s about to become the anchor of my Thread network. Here’s what it actually is, why I’m using it as a Thread border router instead of an Apple or Google hub, and how the setup works.

Disclosure: some links on this page may become affiliate links. If you buy through them, I earn a small commission at no extra cost to you. I bought this unit myself.

What the ZBT-2 actually is

On paper it’s simple: a USB-C dongle that adds a 2.4 GHz 802.15.4 radio to your Home Assistant server. Inside there’s a Silicon Labs EFR32MG24 (Cortex-M33) doing the radio work and an ESP32-S3 acting as the USB-serial bridge. It speaks either Zigbee 3.0 or Thread — you choose during setup, and it can’t do both at once. That one sentence saves you a lot of forum reading.

Compared to the old ZBT-1/SkyConnect, you get more transmit power (up to 10 dBm), a proper detachable 4.16 dBi antenna instead of a PCB trace, and noticeably better resilience against interference. The box includes a desk stand and a USB extension cable — and that cable is not decoration. USB 3.0 ports and SSDs are loud neighbours at 2.4 GHz; putting half a metre between the radio and your server is the single cheapest range upgrade you’ll ever get.

Everything is open source — hardware and firmware — and the enclosure opens without breaking clips, with test pads exposed. Very on-brand for Home Assistant.

Quick specs

• Radio: Silicon Labs EFR32MG24, 2.4 GHz 802.15.4, up to 10 dBm TX
• Bridge: ESP32-S3, USB-C
• Protocols: Zigbee 3.0 or Thread (one at a time)
• Antenna: 4.16 dBi, detachable, omnidirectional
• Works with: ZHA, Zigbee2MQTT, OpenThread Border Router
• In the box: stick, antenna, desk stand, USB-A→C extension cable
• Price: ~$49 / €49

Why Thread, and why not just use a HomePod?

If you own an Apple TV, HomePod, or a Google Nest hub, you technically already have a Thread border router in the house. So why buy one?

Control. With a big-tech hub, the Thread network credentials live in their ecosystem, and your border router stops working the day you change phone platforms or the vendor changes its mind. With the ZBT-2 running Thread under Home Assistant, the entire network — credentials, routing, commissioning — lives in HAOS, on my hardware, with no account attached. Matter-over-Thread devices get commissioned straight through the Home Assistant Matter integration and never touch a cloud.

That’s the same reason this blog runs Home Assistant in the first place: local control isn’t a feature, it’s the point.

How the Thread border router setup works

The concept trips people up, so here’s the short version: the ZBT-2 is not a border router by itself. It’s the radio. Your Home Assistant server plus the ZBT-2 together become the border router — the device that routes packets between the low-power Thread mesh and your normal home network.

1. Plug it in via the extension cable, away from USB 3.0 ports and metal cases. Home Assistant discovers it automatically.
2. Choose Thread during setup. HA flashes the OpenThread RCP firmware onto the stick. (Pick Zigbee here instead and it becomes a ZHA/Zigbee2MQTT coordinator — same hardware, different life.)
3. Install the OpenThread Border Router add-on. It claims the ZBT-2 as its radio and forms the Thread network. The Thread integration in HA shows your network and its credentials.
4. Commission Matter-over-Thread devices with the Home Assistant companion app. Scan the QR code, the device gets the Thread credentials, joins the mesh, and shows up as a Matter entity. Fully local.

From there, every mains-powered Thread device you add (plugs, bulbs) also acts as a router and strengthens the mesh — Thread’s quiet superpower over Wi-Fi gadgets.

Things worth knowing before you buy

• One protocol per stick. If you already run Zigbee, keep your existing coordinator for Zigbee and dedicate the ZBT-2 to Thread (my setup), or vice versa. Don’t plan on one stick doing both.
• Use the extension cable. Yes, I’m repeating it. It matters that much.
• Channel planning: Thread, Zigbee and Wi-Fi all share 2.4 GHz. Keep your Wi-Fi on a fixed channel and let Thread/Zigbee live in the gaps.
• Matter-over-Thread is the future-proofing play. The interesting new sensors and locks are increasingly shipping as Matter-over-Thread first.

Verdict so far

At ~$49 it’s not the cheapest 802.15.4 radio you can buy, but it’s the one built and maintained by the people who build Home Assistant itself — firmware updates arrive through HA, setup is genuinely plug-and-pick-a-protocol, and the open hardware means it won’t become a paperweight when priorities shift. As the anchor for a local-first Thread network, it’s exactly the boring, reliable piece of infrastructure I want.

The full setup walkthrough — OTBR add-on, first Matter commissioning, and the inevitable mistakes — will be its own build log soon. Subscribe to the newsletter below if you want it when it lands.