The Shelly Plus 1 is a small, certified Wi-Fi relay that wires inline to switch a circuit: a pump, a light, a fan, a valve. What makes it the Open Agriculture Technology pick among smart relays is that it answers to you, locally, over a documented API and MQTT, with no vendor cloud required. Pair it with a sensor reading and it turns watching into doing.
What it is.
It is a compact relay module, small enough to tuck into an electrical box behind an existing switch or beside a piece of gear. It switches a single circuit on and off on command, on a schedule, or from a rule. The plain “Plus 1” is a dry switch (no power metering); its sibling the Plus 1PM adds energy measurement if you want to see watts. Inside it is an ESP32-class chip running Shelly’s own firmware, and it can even run small scripts on the device itself.
Local control.
This is the whole reason it earns the recommendation. The Shelly Plus 1 exposes a local HTTP and RPC API and speaks MQTT, so your Home Assistant (or a script you run) controls it directly on your own network. It keeps working when the internet drops, and nothing about your pump’s schedule has to leave the property. That is the own-your-data rule applied to the actuator side: the device is yours, not a subscription. Home Assistant’s built-in Shelly integration finds it locally with no cloud account.
Key facts.
Mains safety.
The Plus 1 switches wall voltage, which deserves real respect. It is built and certified to sit inside a proper electrical box, wired into fixed wiring. If the job means opening a panel or you are not confident with mains, that is the moment to bring in an electrician. If you only need to switch a plugged-in device and want no wiring at all, a plug-in smart plug is the safer beginner choice, as covered on the plugs and relays page.
Where it fits, and where it doesn’t.
Where it fits
- Switching a pump, light, fan, or valve from a rule.
- Local automation in Home Assistant that survives an outage.
- Adding smarts behind an existing wall switch.
- An own-your-data setup with no vendor cloud.
Where it doesn’t
- Mains wiring you are not qualified to do; use a smart plug.
- Energy metering; choose the Plus 1PM instead.
- Safety-critical interlocks; those need proper hardware.
- Battery, off-grid spots; it needs mains power.
Resources & where to buy.
Shelly Plus 1 Home Assistant: Shelly Where to buy Plugs & relays overview
Frequently asked questions.
Does the Shelly Plus 1 need the cloud?
No. It offers a local HTTP and RPC API and MQTT, so Home Assistant or your own script controls it directly on your network, and it keeps working when the internet is down. A cloud option exists but is not required, which is why it fits an own-your-data setup.
What is the difference between the Shelly Plus 1 and the Plus 1PM?
The Plus 1 is a plain relay that switches a circuit on and off. The Plus 1PM adds power metering, so it also reports the watts and energy used by what it controls. Choose the 1PM if you want to measure consumption as well as switch.
Can the Shelly Plus 1 work with Home Assistant?
Yes, through Home Assistant native Shelly integration, locally and without a cloud account. That lets you switch a pump, light, or valve from a sensor reading with automations that keep running even without internet.
Is it safe to install a Shelly relay myself?
It is certified to sit inside an electrical box on fixed wiring, but it switches mains voltage. If the job means opening a panel or you are unsure, bring in an electrician. For switching a plugged-in device with no wiring, a plug-in smart plug is the safer choice.