Efficient Energy Monitoring with the Sonoff S31 Smart Plug

The Short Version

The Sonoff S31 Smart Plug is a small, compact device that lets you take control of your home appliances and monitor your energy usage. Designed with efficiency, it is ideal for those who want to minimize power consumption while maintaining convenience. The S31 works with Alexa and Google Assistant, enabling voice control for effortless operation. Whether you want to track energy use, turn devices on or off remotely, or schedule operations, the S31 has you covered.

This energy-monitoring smart plug is built into a sleek design to fit comfortably into most outlets without blocking other sockets. It's perfect for homes with multiple devices, allowing you to control and monitor them individually. If you're problem-solving how to cut down on electricity bills, this smart plug might be your ideal start!

What Stands Out

The Sonoff S31 Smart Plug offers a variety of features to make your life easier, safer, and more efficient:

• Energy Monitoring: Keep track of your appliances' electricity usage in real time via the eWeLink app.
• Voice Control: Hands-free convenience with Alexa and Google Assistant support.
• Scheduling Capabilities: Set specific times to turn devices on and off, helping reduce energy waste.
• Compact Design: The sleek profile ensures it won't crowd adjacent outlets.
• Remote Access: Control your devices from anywhere using the solid eWeLink app.

With these capabilities, the S31 goes beyond just a power switch; it transforms your routine into a easily smart home experience.

Detailed Specifications

Here are the key technical specifications of the Sonoff S31 Smart Plug:

• Dimensions: 75.7 x 39.7 x 32 mm (Sonoff's spec table)
• Maximum Load: 15 A / 1800 W
• Power Consumption Tracking: Real-time monitoring
• Wireless Protocol: 2.4 GHz Wi-Fi (IEEE 802.11 b/g/n)
• Integration Options: Works with Alexa, Google Assistant, IFTTT
• Mobile App: eWeLink (iOS and Android compatible)
• Input: 120 V AC, 60 Hz (US version)
• Warranty: Sonoff's store advertises 2 years

The plug is compatible with most home appliances, including lights, coffee makers, heaters, and more, making it suitable for nearly any setting.

Ecosystem and Compatibility

One of the standout features of the Sonoff S31 is its smooth connectivity. It works on a 2.4 GHz Wi-Fi network, ensuring a reliable connection without requiring additional hubs or bridges. Integration with voice assistants like Alexa and Google Assistant means you can control your appliances with spoken commands, eliminating the need for manual operation.

The plug also supports IFTTT, which allows you to create custom automation between multiple devices. Whether automating your morning routine or ensuring devices are turned off when you leave, the Sonoff S31 Smart Plug fits into your smart home ecosystem.

How to Use in Your Daily Life

Real-World Applications

The Sonoff S31 is designed for versatility, and these practical use cases highlight its benefits:

• Save Energy: Use the energy monitoring feature to identify high-consumption devices and optimize their usage patterns.
• Effortless Morning Routine: Schedule your coffee maker to turn on before you wake up.
• Enhanced Safety: Remotely switch off devices like space heaters or curling irons when you're out of the house.
• Holiday Lighting: Automate decorative lights to turn on and off at specific times during the season.
• Eco-Friendly Living: Track and fine-tune your appliances' energy consumption to reduce your carbon footprint.

This device can help you manage devices more intelligently while ensuring convenience and safety.

What a Plug Can and Can't See in a Whole-House Build

Here's the limit nobody prints on the box. A metering plug measures whatever somebody remembered to plug into it, which in my house rules out nearly everything that matters. The heat pump is a Gree Versati III SPLIT 10 kW, wired into the board and talking to Home Assistant over Modbus. The ten heating zones are driven by Sonoff panels flashed for Home Assistant. Lighting is permanently powered at the fixture. None of that ever passes through a socket.

So the metering in my house sits where the loads actually are: a Tuya TONGOU 50A breaker with measurement on the DIN rail, plus a Huawei EMMA-A02 alongside the inverter for the import and export picture. The second TONGOU breaker I have, a 63A one, comes without metering and reports nothing, so read the listing before you order. A plug you can move to a different appliance tomorrow. A breaker with no metering stays blind.

There's a second reason to hesitate before building an energy picture out of Wi-Fi plugs, and it has nothing to do with accuracy. My Zigbee gear has come through two controller changes, because Zigbee doesn't care who the coordinator is. The Mi Home Wi-Fi devices from the same era didn't survive, since they depended on one app and one account. A plug that reports through one app and one account is a plug whose history ends the day that account does. I also have a Zigbee switch with metering, and honestly that's the right role for this whole class of device: a spot check, not a system.

Setting Up the Sonoff S31 Smart Plug

Getting started with the Sonoff S31 Smart Plug is simple:

1. Plug It In: Insert the S31 into any standard outlet in your home.
2. Download the eWeLink App: Available on both Android and iOS platforms.
3. Connect to Wi-Fi: Make sure your phone and the device share the same 2.4 GHz Wi-Fi network during setup.
4. Pair the Plug: Follow the guided steps in the app to connect the smart plug.
5. Start Using Features: Use the app to schedule appliances, turn devices on or off, or monitor energy usage.

Setup is a short job and doesn't require advanced technical skills. One buying note: the S31 page is shared with the S31 Lite, which has no energy monitoring, so pick the model name carefully. Sonoff's UK store showed the plug as sold out in October 2026, with a sale price of 11.76 GBP.

Troubleshooting Tips

• Ensure your Wi-Fi network operates at 2.4 GHz, as the device does not support 5 GHz bands.
• Reboot the plug and app if issues arise during pairing.
• If Alexa or Google Assistant fails to recognize the device, verify the linked app accounts are synced properly.

The Good and the Not-So-Good

Pros:

• Real-time energy usage tracking
• Supports voice control for enhanced convenience
• Compact, space-saving design
• Affordable price point
• Easy setup with intuitive app controls

Cons:

• Only supports 2.4 GHz Wi-Fi networks
• Doesn't include advanced surge protection
• Limited to indoor use only

Final Thoughts on the Sonoff S31 Smart Plug

The Sonoff S31 Smart Plug is a fantastic addition to any smart home, particularly for those seeking to reduce energy consumption and enhance daily convenience. Its energy monitoring, compact size, and compatibility with Alexa and Google Assistant make it a standout choice for users. While it has minor limitations, like operating only on a 2.4 GHz Wi-Fi network, its affordability and solid features easily outweigh any drawbacks.

If you're looking for an easy way to control devices remotely and learn more about your energy habits, the Sonoff S31 is an excellent pick. It's simple to use, offers reliable performance, and integrates well with other smart devices. Whether you're a smart home beginner or a seasoned pro, the Sonoff S31 adds value and efficiency to your daily life.

By incorporating this smart plug into your living space, you're not only upgrading your home but also contributing to a more energy-conscious lifestyle. Ready to take the next step? Explore the Sonoff S31 Smart Plug today!