I’ve mentioned a couple of times in my reviews that I consider energy metering gadgets the most practical smart devices you can add to your Smart Home. Knowing the energy consumption of a particular device, appliance, room or even your entire home can give you useful insights on saving energy.
In this review, I’m testing a Zigbee Bidirectional Energy Meter model PJ-MGW2201 with a 150A CT Clamp, meant for measuring PV solar panels production and net energy usage. The device does basically the same thing as the Zemismart SPM01, although it’s cheaper and has a bigger CT clamp.
I got it on AliExpress for $25, although you can get it for $35 on Amazon too if you do not want to wait.
Here’s a list of other energy metering devices I’ve tested so far, each meant for the same purpose but for different use cases and installation methods:
- Monitoring high power appliances
- Monitoring a single phase (appliance, extension cord etc.)
- Monitoring 3 phases (entire home)
- Model: PJ-MGW2201
- Manufacturer ID: _TZE204_ac0fhfiq
- Connectivity: Zigbee/Wi-Fi
- Input Voltage: 110-240VAC, 50-60Hz
- Measuring Range: 0.1A – 150A
- Max Current CT Clamp: 150A
- Max Diameter CT Clamp: φ16mm
- Operating Temperature: -10°C ~ 55°C
- Dimensions: 93x55x30mm
- Dimensions CT Clamp: 46x30mm
- Cable Length CT Clamp: 1.5m
- Energy Meter Accuracy: Class 1
Package Contents and Teardown
The Tuya Bi-directional Energy Meter ships in a cardboard box containing the device itself, the 150A CT clamp, some screws/sticker for installation and a user manual. Although common and not really important, the packaging and branding of this device feels like a DIY project a lot, it certainly could use better branding.
I felt like I’ve seen this particular case before, and after some digging it turned out to be reused from this 16A smart switch or visa versa. Which came first, the chicken or the egg?
There is a pairing button with an LED indicator on the top and 4 screw terminals at the bottom, covered with a slide-out plastic cap.
Removing the PCB from the case, reveals a neat and tidy layout of components. The black color is insignificant, although it’s rare and found mostly in Aqara‘s product line-up.
The screw terminals are shielded from one another with high plastic dividers, to prevent any strays from making contact with an adjacent terminal. The device uses a STM32G030F6 [Datasheet] MCU with 32 Kbytes of Flash memory to handle operation and energy metering logic, as well as keep any readings in memory for a period of time.
Zigbee communication is enabled by a Tuya ZT2S Module [Datasheet] with a low-power 32-bit CPU, 1024-KB ﬂash memory, 64-KB RAM, and rich peripherals. This module also powers the Colorock 30A Energy Metering Relay for high power appliances, which is basically a smart switch with energy monitoring capabilities.
Once I assembled the device back the way it was, it was ready to test and pair to Home Assistant. Considering the CT Clamp is 150A, it’s bigger than previous devices of this type. It’s important to remember this when choosing your installation location.
Installation and Wiring
This Tuya Bi-directional Energy Meter is simple to wire and install, much like the Zemismart SPM01. The user manual includes a diagram for the most novice users too, just make sure you’ve turned of the power of the input wires:
- Connect the CT clamp to the S1 and S2 terminals
- Connect the L-live and N-neutral wires to the L and N terminals
- Power on the device
First, you must pick a location for installing the CT clamp. Usually it’s attached just before the two-way energy meter from your provider, but depending on your setup you might be able to attach it elsewhere.
Second thing you need to be mindful of is the orientation of the CT clamp. There is a small arrow on the bottom pointing from K towards L, which is the direction of the current flow towards the load (house, appliance etc.). Helpful image from the manufacturer:
Home Assistant Integration
The Tuya Bi-Directional Energy Meter PJ-MGW2201 is supported in Zigbee2MQTT and partially in ZHA with a custom quirk. To pair the device, press and hold the button for ~5sec until the LED starts blinking:
Once paired to your coordinator, the device is identified as model TS0601_bidirectional_energy_meter by manufacturer _TZE204_ac0fhfiq. Since it’s mains powered, it’s also a router capable or relaying Zigbee traffic from adjacent devices. It exposes the following entities in Home Assistant through Zigbee2MQTT:
- Energy: Sum of consumed energy in kWh
- Produced energy: Sum of produced energy in kWh
- Power: Instantaneous measured power in W
- Voltage: Instantaneous measured voltage in V
- Current: Instantaneous measured electrical current in A
- Energy flow: Direction of energy flow – consuming or producing
- Linkquality: Signal strength in LQI
The device has a memory chip which remembers any reading fluctuations before sending its payload to Zigbee2MQTT or a Tuya Hub if you are using one, the reporting interval is exactly 5 minutes. In the event of a connectivity drop, it can store the data by itself for 1 month.
The Energy flow entity can tell you whether you are currently producing or consuming energy, depending on the net difference between the two. This is a helpful piece of info for automations and dashboard design.
There is an ongoing discussion about the development of a proper quirk for this device which you can follow in this thread. If you apply the custom quirk that’s available in the thread, you will get:
- Active power
- RMS current
- RMS voltage
- Summation delivered
If you rely on ZHA as your main Zigbee integration, I would skip this device. ZHA is seriously behind Zigbee2MQTT when it comes to devices of this type, and there is no telling if it will ever work correctly. You always have the option to switch to Z2M, which I highly suggest.
Since I do not have solar panels, I decided to benchmark the accuracy of the energy consumption against the Zemismart SPM01 which I tested recently. The SPM01 is also a bidirectional energy meter, meant to be installed under a circuit breaker which is why it’s so small.
I stripped an extension cord with three sockets and isolated the phase. After verifying that the neutral and phase are correct with the Kaiweets Multimeter I attached both the Tuya PJ-MGW2201 and Zemismart SPM01 to the live wire and paired both of them to Zigbee2MQTT.
I plugged in a water heater, a desktop PC and a pair of speakers in the extension cord to create some energy consumption. After measuring the values for a few hours, I recorded the reading of the sensors for each incremental hour:
|Tuya PJ-MGW2201||Zemismart SPM01|
Even though the reading skewed at certain points in time, the final accumulated value was correct with an average offset of ~0.45%. This was enough for me to conclude that the Tuya PJ-MGW2201 is a fairly accurate device, all things considered. Screenshot from developer tools:
For anyone wondering how I calculated the average offset: I use the History Explorer Card in Home Assistant to graph most energy, temperature and humidity charts for devices I test and review. The card has a neat future which allows you to easily export data as a CSV file. From there, it’s just basic math in Excel.
Naturally, the obvious use case scenario and target marketing for this device is to use in a residential PV solar panel plant. This will give you a sum of produced and consumed energy, which is a great overview for tracking PV plant performance.
However, this device can measure energy consumption in one direction too. You do not have to attach it to next to your energy meter and can just use it wherever you like. For example, ever since I tested the Zemismart SPM01 I installed on an extension cord powering my whole server room (I reset it for this test).
Potential use cases:
- Server room
- Computer fleets
- Heating/Cooling equipment
- Domestic appliances (dishwasher, dryer, stove etc.)
The Tuya Zigbee Bi-Directional Energy Meter PJ-MGW2201 turned out to be a solid device, just like I expected. The reason I was confident in this energy meter is because the official store that sells these is MatSeePlus on AliExpress.
They produce almost exclusively energy metering devices and I already reviewed and tested two of their products: The Tuya PJ-MGW1203 (Single phase) and Tuya PC321-Z-TY (Three phase), which turned out great. The PC321-Z-TY is installed as my main home energy meter for about 5 months now.
ZHA support appears to be non-existent for these types of sensors. You are either required to dig through community forums and apply questionable custom quirks or you can’t use the device at all. Of course, you can always choose the third and best option – migrate to Zigbee2MQTT.
If you find a use case for this Tuya Bi-Directional Energy Meter, the device is available on AliExpress and Amazon. Bellow are links for other devices I’ve tested that serve the same or similar purpose:
- Tuya Single Phase Energy Meter 80A CT Clamp PJ-MGW1203
- Tuya Home Energy Meter 3-Phase 80-500A Clamps PC321-Z-TY
- Zemismart Bi-Directional Energy Meter 63A CT Clamp SPM01
- Zemismart Bi-Directional Energy Meter 3-Phase 63A Clamps SPM02