The trend of measuring the energy usage of household appliances has become increasingly popular among smart home users over the past few years. I received the new SONOFF POW Ring smart power meter switch device from ITEAD for review. Unlike SONOFF’s existing energy monitoring devices such as POW Elite, SPM, DualR3, POW3, and POW Origin, this new device, also known as POWCT, utilizes a current transformer (CT) to control the flow of current, i.e. Measure the total power. This method eliminates physical contact with live wires, reducing risks during installation.
Additionally, it can measure up to 100A of current, which is a significant increase compared to previous models. This makes it suitable for measuring power usage at the main circuit breaker, energy generated from solar panels, and even home chargers for electric vehicles (EVs). The SONOFF POW Ring we’re testing today is not only a smart power meter, but also a switch, and in addition to measuring and managing energy usage, it also features a small relay. The POW ring operates via WiFi and is managed using the same eWeLink software as his other SONOFF devices. Before we delve into the details of the POW Ring, let’s take a look at the comparison chart with other members of the POW family.
Unboxing the SONOFF POW ring
The main items included are an instruction manual, antenna, POW ring unit, and CT clamp. The POW ring unit has slots on both the bottom and top for inserting wires. The antenna port is on the top and installing the antenna is optional to get a good Wi-Fi signal when installed in the cabinet. On the front, there is an LCD screen to display various data, one button to change the displayed values and enter pairing mode, and LEDs to indicate WiFi and power status. Apart from the SSMA connector for the antenna, there is also an RJ9 port nearby for connecting the CT clamp.
The bottom slots (L and N) of the POW ring are for connecting to a power source. The NO slot and COM slot are relay terminals for controlling other devices. Operates as a dry contact with a maximum specification of 2A. As seen in the image, there is only one RJ9 port for connecting the CT clamp, indicating that it can only be used with single-phase power. I asked SONOFF if they have any plans for a three-phase model, but they are still considering it depending on demand. If you are interested, you can provide feedback through our social media channels.
Some households sell excess power back to the grid, with power flowing in either direction depending on usage and production (e.g. solar panels). Currently, there is no bidirectional energy measurement capability. SONOFF mentioned plans to implement this feature through a software upgrade in the future. The image below shows both wiring configurations. One uses no relay, and the other uses a relay to trigger a magnetic contactor to control high-load electrical equipment.
SONOFF POWCT teardown investigation
I took apart the SONOFF POW Ring (POWCT) a little. As mentioned in the specs, it has an ESP32 chip inside. SONOFF has been working since last year to upgrade the internal chips of new smart home devices from his ESP8266 to the new ESP32. Apart from being faster, you should be able to easily flash any other firmware, be it Tasmota or ESPHome, with clearly marked pins for this purpose, so it’s a boon for DIY enthusiasts is. This simplifies the firmware flashing process. However, neither project had working firmware ready for the new devices at the time of review, so we did not conduct any flash experiments.
SONOFF Pauling review by eWelink
First, we tested eWeLink (v.5.30) on an iPhone running iOS 17.3.1. The pairing process is similar to adding other SONOFF Wi-Fi devices. Press and hold the single button on the top of the POW ring for 5 seconds to enter pairing mode, indicated by a flashing light. From the eWeLink app, I added the device as usual by tapping the “+” sign. The steps are roughly as shown in the diagram below. Or see the user manual for more information.
Once I was ready to use the POW ring, I tested it by measuring the energy usage of my office’s evaporative air cooler (yes, it’s hot here in the summer!). I experimented with adjusting the fan speed to observe the energy usage updates. Data updates were almost instantaneous, with the slowest update observed occurring within 5 seconds. Similarly, if you use Home Assistant, the update speed will be about the same. However, we did not test bidirectional energy measurements as they are not yet available until a future firmware update.
From the “Energy Overview” screen, you can check the details of your energy usage in real time, daily, monthly, and yearly. Even if you stop using POW Ring, historical data is retained for up to 6 months before being deleted. This will give you enough time to download and save locally if needed.
Two interesting features I discovered while managing my POW ring using the eWeLink app are “Threshold Settings” and “Push Notifications.” Threshold settings work with the included relays to set current, voltage, or power thresholds. When these thresholds are exceeded or below, a relay is triggered to turn the load on or off. Additionally, push notifications allow you to set up notifications when your energy usage exceeds or falls below a defined threshold. This flexibility can prove useful in a variety of scenarios.
Review of SONOFF Pauling with Home Assistant
I used Home Assistant version 2024.2.4 running on a Raspberry Pi 4. The addition of the POW ring was automatic through the integration of AlexxIT Sonoff LAN (v.3.6). At the time of our testing, AlexxIT Sonoff LAN would not have tested POW Ring yet. However, the POW ring worked right out of the box, just like SONOFF’s other energy monitoring products. Data includes current, voltage, wattage, and energy usage for the day and month. Home assistant enthusiasts can further leverage this data for additional calculations and automation. There is a switch at the top, which is the relay I mentioned earlier. Its main purpose is to trigger the magnetic contactor to turn the device on or off, and it can handle currents up to 2A.
conclusion
Sonof has finally introduced “POW Ring”, a CT energy monitoring device that provides safe energy monitoring without having to mess with electrical wiring. It can measure up to 100A, which is sufficient for most homes. The included relay switch allows you to easily control other devices through threshold settings or create additional scenes and automation. Fans of SONOFF/eWeLink will definitely appreciate this addition.
Thank you to ITEAD for sending me the SONOFF Paw Ring for review.The company sells the SONOFF Pow Ring smart power meter Just $34.90 at Online StoreAnd as always, CNX Soft Soft A coupon for a 10% discount on devices or other items from the ITEAD shop.
A computer engineer who previously worked in a multinational IT company, has extensive experience in IT infrastructure and is passionate about the Internet of Things, i.e. smart homes, smart farms, renewable energy, organic farming, etc. I’m also interested in sustainability.
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