HomeHome AutomationShelly 2.5 vs Sonoff DualR3

Shelly 2.5 vs Sonoff DualR3

It's time for the battle: Shelly vs Sonoff

As Sonoff DualR3 enters the market, it’s only fair to make another vs video with its twin from Bulgaria: Shelly 2.5. Just like with Shelly 1 vs Sonoff Mini I hope that the article sparks a discussion about what home automation enthusiasts appreciate most. Both devices Shelly 2.5 (review) and Sonoff DualR3 (review) offer the same functions, therefore it’s definitely a good idea to take a closer look and talk about differences.

Pitching Shelly 2.5 vs Sonoff DualR3

Sonoff DualR3 is new to the market. Upgraded and redesigned not just on the inside (runs ESP32) is much smaller and offers extra functionality over Sonoff Dual R2. Just like Shelly 2.5, both devices aim to automate dual-gang switches or small motors driving shades, motorised rollers etc. The biggest difference between these two devices is the microcontroller that dives them. ESP32 is the bigger, better, stronger, faster brother of ESP8266, but is it enough to compete with Shelly 2.5?

Shelly 2.5Sonoff DualR3
ESP8266ESP32
110-230V ±10%, 50/60Hz AC100-240V ±10%, 50/60Hz AC
24 – 60V DCno
2 Channel 10A per channel2 Channel 10A per channel (15A Max)
WiFi 802.11 b/g/nWiFi 802.11 b/g/n
39mm x 36mm x 17 mm54mm x 49mm x 24 mm

Both devices support 2 channels with individual inputs for switches. Each channel is capable of power metering and the power consumption is displayed in the app. On the surface, Shelly 2.5 vs Sonoff DualR3 seems like an even fight, but things always get more interesting upon closer inspection.

Hardware

Shelly 2.5 is smaller than the competitor, comes with an exposed header for development at the back and 7 terminals to connect 2 switches, 2 light sources and power (or switch and motor). It’s powered by ESP8266 which control 2 relays capable of 10A each, which can run at full power rating independently. I couldn’t find an inductive rating for motors, so be cautious, if you are going to drive a motor. Extra points for the ability to run off the DC power.

Sonoff DualR3 is slightly bigger but comes with a DIN rail clasp and terminals are much bigger. It doesn’t offer extra GPIOs (although some dev pads are available for flashing). The unit is driven by ESP32 that controls 2 relays rated also 10A each. Unlike Shelly 2.5, Sonoff DualR3 suggest 15A total current limit for both relays. The inductive current rating is 1A which is enough to drive a small motor.

Shelly 2.5 may seem like a clear winner in this category until you consider two factors. An average socket/light fitting is fused with 16A, so you are unlikely to take the advantage of the full power of Shelly. On top of that, the small size can be misleading, as Shelly’s terminals are small, and you won’t be able to fit multiple wires (needed for Neutral). Adding WAGO style connectors solves the issue, but increases the overall footprint of the Shelly device. If you add 2 gang and 2 switches to each, you will probably need connectors for both of them.

Software

Shelly 2.5 and Sonoff DualR3 come with Shelly Cloud and eWeLink apps. These are well integrated in Google Assistant and Alexa ecosystems and offer cloud connectivity wherever you are. Both apps offer also standard features like individual channel control, power metering and timers and schedules. It’s the software that sets these two apart.

Physical Switching

Both devices work well and are responsive to physical switching and virtual toggles. eWeLink app and Shelly Cloud updates the information almost instantly.

Shelly 2.5 offers 5 different switch modes (momentary, toggle, edge, detached, activation) which can also be inverted which will suit every possible switch configuration that you may have at home.

Sonoff Dual offers 3 modes (toggle, momentary, edge) only. These cover 90% of the use cases so you shouldn’t have problems connecting the gadget to your light switches.

Both devices will cover your basic needs, but if you require much greater flexibility in how you want to use your wall switches, then Shelly 2.5 is a better choice.

Power Metering

Shelly 2.5 and Sonoff DualR3 offer per channel metering. While shelly offers total power consumption figures and current power draw. A really nice feature of Shelly 2.5 is the ability to display the total consumption of the room based on all Shelly devices inside it (you can exclude individual devices from that metric). It’s a great little shortcut that more ecosystems should adopt.

Sonoff DualR3 don’t offer per room power usage but it goes a step further with additional metrics like real/apparent/reactive power, voltage and current information. These are available per channel and there is an additional menu to measure power consumption for a brief time window which could be useful for troubleshooting things.

The metering figures for both devices are very similar, and I have no issues with the accuracy of either of these. While Sonoff DualR3 may be my personal favourite here for disclosing more power metrics, I have to admit I’m fond of Shelly’s room consumption feature.

DIY automation

Shelly 2.5 has no competition here. Sonoff DualR3 comes without Sonoff DIY and offers no additional connectivity, while Shelly 2.4 goes the extra mile delivering Cloudless operation, REST API and MQTT (although active MQTT protocol will disable cloud).

An interesting feature of Shelly 2.5 is the ability to trigger custom REST calls based on predefined conditions like relay status change. These can be used to interact with other ecosystems. For anyone who doesn’t like Cloud, Shelly 2.5 also offers a web-server based interface with all functions available. In this mode, the device doesn’t need the Shelly Cloud app to work and can be accessed directly via IP.

Sonoff DualR3 has nothing to offer here without flashing custom firmware. If you want to interact via Home Assistant or NodeRED, you will need to flash Tasmota on it. The only consolidation for Sonoff DualR3 is Tasmota development. As the relay comes with ESP32 inside, custom firmware opens exciting opportunities for Bluetooth mesh networks and more. As exciting as this sounds, it’s not a part of the stock firmware at the moment and therefore I won’t be using this as an argument to combat Shelly’s excellent Cloud options.

Price

Shelly 2.5 will set you back 19.99€ ($23) while Sonoff DualR3 costs almost half that $13.98. It’s a considerable price difference that will quickly add up if you aim to buy more than one device. The question that you have to ask yourself is the cheaper price of Sonoff DualR3 justifies the time you will spend hacking it? Personally, I don’t mind doing it, but you may prioritise comfort over savings.

Final thoughts

Shelly 2.5 is in the lead this time. Sonoff DualR3 doesn’t cater to DIY home automation fans and even with a much lower price, it may struggle to attract attention. Perhaps the situation will change with future updates. After all, Sonoff DualR3 is a much younger device, rocks a more modern ESP32 microcontroller and costs less. But for now, if you are looking for automation freedom where multiple gangs are concerned, Shelly 2.5 is a better choice. What do you think? Let me know in this Reddit thread.

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