Sonoff S20 Smart Socket Review

Note: Please, be aware that this post may contain affiliate links.

Store Price Link
Amazon [amazon_link asins=’B076Z9GWSZ|B072ZT9NW5|B078BMKD9R|B07CGBHFS9|B0749KD5V2|B078BMKD9R|B07869Y3M6|B077M7RYVQ|B07H68F64K’ template=’PriceLink’ store=’hasscasts_website-20|hasscasts_website-21|hasscasts_website0a-21|hasscasts_website03-21|hasscasts_website07-20|hasscasts_website0ea-21|hasscasts_website07-21|hasscasts_website01-21|hasscasts_website0a-22′ marketplace=’US|UK|DE|FR|CA|IT|ES|IN|AU’ link_id=’fb608b4f-a8c2-11e8-a264-99b72b4bbf4f’] [amazon_link asins=’B076Z9GWSZ|B072ZT9NW5|B078BMKD9R|B07CGBHFS9|B0749KD5V2|B078BMKD9R|B07869Y3M6|B077M7RYVQ|B07H68F64K’ template=’TitleLink’ store=’hasscasts_website-20|hasscasts_website-21|hasscasts_website0a-21|hasscasts_website03-21|hasscasts_website07-20|hasscasts_website0ea-21|hasscasts_website07-21|hasscasts_website01-21|hasscasts_website0a-22′ marketplace=’US|UK|DE|FR|CA|IT|ES|IN|AU’ link_id=’fb608b4f-a8c2-11e8-a264-99b72b4bbf4f’]
USA 13.42 USD
UK 10.33 GBP
EU 11,77 EUR
Canada 17.64 CAD
Australia 17.98 AUD

All including delivery
Prices correct on 17 Oct 2018

Sonoff S20 at AliExpress

How good is the Sonoff S20 Smart Socket? in this review, I’ll give you my honest opinions and I’ll tell you whether I think you should splash the cash and buy one.

What’s in the box?

As one would expect from Sonoff, the contents are quite sparse. You get what you need; nothing more, nothing less.

  1. Sonoff S20 smart socket
  2. Warranty card in English and Chinese
  3. Instructions in a variety of languages

Build Quality

The S20 is built sturdily enough for what it’s designed to do. As with most smart sockets, it’s made out of plastic (if you know of one that isn’t then you can send your answers on a postcard or leave a comment below).


The functionality I have a slight problem with, to be honest. As you can see from the above picture, the socket has the circular push-button switch below the socket. This can lead (no pun intended) to the wire covering the push button. This may not be a problem if either you are using the socket as a purely remote socket that won’t be operated by the push-button switch or if you have a thin wire that you don’t mind moving to one side every once in a while.


The integrations listed on the website are:


As a lay-person, it seems to me that the Sonoff S20 is safe to use. On the Sonoff website, It is listed as having CE, FCC and RoHS certification. There are, however, products out there that do not have the Sonoff logo on them, and I am not sure whether these are fake products, not qualifying for certification or whether they are from authorised distributors. If anybody has information on this then please leave a comment so that we can find out.

However, if you’re like me, and you like to open these things up and install Tasmota on them, you are literally playing with fire. If you solder new headers in, that is a ridiculous thing to do but some of us do it.

If you’re worried about whether an item is genuine or not, then I would highly recommend the HS100 from TP-Link. It is well made and doesn’t come with the same negative connotations as the Sonoff.

[amazon_link asins=’B076Z9GWSZ|B072ZT9NW5|B078BMKD9R|B07CGBHFS9|B0749KD5V2|B078BMKD9R|B07869Y3M6|B077M7RYVQ|B07H68F64K’ template=’ProductAd’ store=’hasscasts_website-20|hasscasts_website-21|hasscasts_website0a-21|hasscasts_website03-21|hasscasts_website07-20|hasscasts_website0ea-21|hasscasts_website07-21|hasscasts_website01-21|hasscasts_website0a-22′ marketplace=’US|UK|DE|FR|CA|IT|ES|IN|AU’ link_id=’fb608b4f-a8c2-11e8-a264-99b72b4bbf4f’]


The S20 uses Sonoff’s EWelink app to control the sockets remotely. Now, unlike the very early version of this software, I tried several years ago. This version is a comparable dream to use. It is straightforward as one would expect from a modern app.

In order to use the S20 remotely, without modifying the firmware you will need to register for a free EWelink account.

To set it up

  1. open up the EWelink app
  2. log into your account
  3. press the push-button switch for 7 seconds until the green switch starts to rapidly flash
  4. select the socket you want to configure
  5. input your WIFI details
  6. when the WIFI LED is on, you’re connected


When it comes to the price, this is one area that I look very favourably on the S20. It is quite inexpensive for a decent WiFi-based smart socket.

At the time of writing this


The Amazon price is easy to get, the price here should be for the Sonoff S20 from the nearest Amazon store to you:

Price: [amazon_link asins=’B076Z9GWSZ|B072ZT9NW5|B078BMKD9R|B07CGBHFS9|B0749KD5V2|B078BMKD9R|B07869Y3M6|B077M7RYVQ|B07H68F64K’ template=’PriceLink’ store=’hasscasts_website-20|hasscasts_website-21|hasscasts_website0a-21|hasscasts_website03-21|hasscasts_website07-20|hasscasts_website0ea-21|hasscasts_website07-21|hasscasts_website01-21|hasscasts_website0a-22′ marketplace=’US|UK|DE|FR|CA|IT|ES|IN|AU’ link_id=’fb608b4f-a8c2-11e8-a264-99b72b4bbf4f’]


If you want to pay a little less and are willing to wait a week or two, you can easily get the S20 from Chine via AliExpress. Until they approve my API key, I’ll manually list the prices for countries where most of my user base comes from.

The link for all countries is exactly the same, and select your country/currency from the top-right corner of the page

View the Sonoff S20 on AliExpress and get a live price.

USA 13.42 USD
UK 10.33 GBP
EU 11,77 EUR
Canada 17.64 CAD
Australia 17.98 AUD

All including delivery
Prices correct on 17 Oct 2018

They ship to almost any country so if it’s not listed, it’s just because I don’t want to spend time going through every country when the ones above are my main user-base.

Flashing custom firmware

If you so wished, you could replace the Sonoff firmware with your choice of firmware, like Tasmota, which will allow you to use the socket totally locally and not have to rely on the external servers of Sonoff/Ithead. Tasmota will allow you to control the S20 on a local network system using MQTT, that way, your data never leaves your network unless you want it to.

Special thanks to Taste in the comments below who points out that if you turn ledmode to 0 then the LED is only blue when it is turned on

Read the comment

Technical Specifications

Input Voltage
90-250V AC 50/60Hz
Output Voltage
90-250V AC 50/60Hz
Max. load
220V 10A
WiFi standard
2.4GHz b/g/n
Security Mechanism
Operating Temp.
0℃ – 40℃
Operating Humidity
5% – 90%
Fire-retardant PC (FR-ABS)
Max. Power
Max. Current


In general, I like the Sonoff S20 Smart Socket and if I had to equip my house with smart sockets and I had to choose from the ones I’d tried so far (and I had to pay for them), I’d definitely choose the S20 due to its flexibility and price. I would then flash them all with Tasmota, and control them locally using Home Assistant and MQTT.


One word of warning on the Sonoff S20, and any device such as this, whether it be a Sonoff Basic or a TP-Link HS100: make sure you only use these with items that have a power consumption they can handle.

As an example, the Sonoff S20 can handle 10 Amps or less. The manufacturer of the product you want the S20 to control will normally have included this in the technical information that came with the product, or you may find it on the website. If you are in any doubt, whatsoever, then stop, and consult a qualified electrition.

If you know what you’re doing, and you have a multi-meter, you can measure the Amperage using that.

Do you own a Sonoff S20 Smart Socket?

If you own one of these gems, then please let us know in the comments below. What do you think of them and how would your review differ from mine?

Alternatively, if you want one of these, then what is it that attracts you to the S20? Again…let us know in the comments below.

Full Disclosure

Most of the links in this post, especially the ones to AliExpress and the Amazon stores, are affiliate links. That means that if you visit the links and then purchase anything, I may get a small percentage of the sale (typically around 4-5%). It means that you will be supporting me and my effort to get off of disability benefits and make HASSCASTS a full-time career.

As usual: I love you all and my Family and I thank each and every one of you for your support.


I am a disabled veteran of 3 tours of Iraq and a tour of Afghanistan as part of the British Army. No longer able to work as I have to lay down on a sofa-bed in my living room 20-ish hours a day. I'm hoping to be able to make a living blogging about my Home Automation /Smart Home journey and maybe regain some dignity in life.

3 thoughts on “Sonoff S20 Smart Socket Review

  • October 19, 2018 at 21:38

    I have ~10 S20 in my house running for 6 month now. All works fine. One is a bit open because a screw broke but this could be my own fault of maunting it too firmly after the reflash.
    I use them with Tasmota versie 5.14. If you switch the ledmode 0 (via the console) it is only blue when on this looks better πŸ™‚

    • October 19, 2018 at 23:57

      Hey, thanks for the comment, yours was/is the very 1st comment on the HASSCASTS website πŸ™‚
      I’ll put your tip about ledmode in the post now πŸ™‚

      • October 20, 2018 at 08:00

        I checked the command and it is actually ‘ledstate 0’ Thought my memory was better πŸ™‚
        I have bought mine at Banggood who seems to have the best prices for Sonoff devices ~$10,-


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