HomeHome AutomationShelly Duo - going beyond twice

Shelly Duo – going beyond twice

Shelly of two!

After dipping the fingers in smart light switches, it’s only logical that Shelly would introduce their own smart lightbulbs. After all switches like Shelly 1 (review), Shelly 1PM (review), or Shelly 2.5 (review) are great, but may not suit all the circumstances. Sometimes a good old smart lightbulb is the way to go. And that’s how I got Shelly Duo bulbs. Two of them, to be precise. That’s probably the only justification for their name! Are they a stroke of brilliance or just your regular bulbs?

Shelly Duo in action

On the outside, there isn’t much to tell you. A typical smart-looking bulb with screw-in fitting (E27), white colour and a white, plastic dome. There is no revolution there. To find out what makes Shelly Duo shine brighter than the other ones, we have to get it connected.

I already have forthcoming expectations after using Shelly switches. A well-designed web server that works without an app and a cleverly designed app are strong arguments for using Shelly Duo over other choices.

Outstanding features are already visible in the web-based interface. A built-in “night mode” and power metering. Any home automation enthusiast appreciates features that work when everything doesn’t. Setting different brightness levels at night is possible with other lightbulbs, but the implementation is often done via the cloud. If you lose the cloud connection, the bulb won’t dim the lights.

With Shelly Duo, this is baked directly into the firmware. I welcome the move, even if realistically speaking, I don’t think it will happen all that often. I’m always in favour of any controls given to consumers without forcing them to use the cloud.

The built-in power metering feature is another option that Shelly embraces. Dedicated power metering contributes (optionally) towards the total power consumption of each room, painting a picture of how one uses their smart home. I cover the cost of using smart lights in this article. If you want to know how much the smart home costs you, you can read the article, or start investing in Shelly devices. Either way, it’s a feature I really appreciate.

All about lumens

Shelly Duo sports 800 lumens and comes with a colour temperature range of 2700K-6500k. It’s nothing to write home about as it’s what I have seen across bulbs covered in the past, but the addition of softening the transition speed is very welcome. Many devs could take the page from Shelly’s way of doing things.

To my eye, Shelly Duo lights up the room sufficiently and the colour range creates a spectrum for work and chill. There is no flickering, even when looking at the dimmed bulb with my phone camera.

The only area of improvement would be the dimming loop when the transition time is set to ie 5000 ms. The last couple of steps when dimming the light are not smooth. Stepping is noticeable. It last only a brief moment, I hope it will get addressed in a patch.

Going beyond

What Shelly considers “standard” is beyond most other lightbulbs. Yeelight bulbs come with complete API and Tasker integration which won my heart instantly, Shelly Duo uses REST API to let external devices know that the light had been toggled. If that’s not enough, developer options in the web interface hide MQTT access. You can take the advantage of this protocol as long as you don’t mind losing cloud connectivity.

It’s probably the only downside to Shelly Duo. I still secretly hope that MQTT will become available without dropping the support for Shelly Cloud, just as they implemented it with the Shelly Motion (review) sensor. Otherwise going totally LAN only with MQTT controls leaves you with integrations like Alexa for NodeRED or Nora.


Off the shelf, there is a Shelly Cloud, that integrates with Alexa, and Google Assistant. The linking process is quick and painless. Once connected, Shelly Duo is very responsive to commands with switching happening almost instantly (unless transition time had been set).

Actions let you ping other services, to let you know when the lights are toggled, and building in automation panel into Shelly Cloud gives you simple automation based on interactions with other Shelly devices, timers or environmental factors.

Get Shelly

Check out other devices from the Shelly series to build your ultimate DIY automation:

Final thoughts

You can snatch Shelly Duo from their store for about €9 which isn’t expensive considering how well-designed Shelly is. I’m planning to cover Shelly MQTT use with NodeRED in the nearby future, so if you want to tag along, keep your eyes peeled on my page. For now, treat yourself to a lightbulb or two and see how it goes. If you are not sure where to get a lightbulb and where to use a switch – I also have an article all about smart switches. Let me know your thoughts about Shelly Duo in this Reddit thread.

🆓📈 – See the transparency note for details.


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