Three phase power meter

Is there any good solution for three phase power metering?

The Shelly EM is oriented to the US market with two phases, the Youtube video promoted by HA wrt to Energy dashboard lists a nice board (6 ch esp32 engergy), but is US based so getting it shipped to Sweden costs a fortune (the board is €70 and shipping €40). The clamps recommended in the video are shipped from Poland

The esp32 and the clamps are no problem, so has anyone found an affordable solution based on European distributors - even if this fall has seens electicity cost skyrocketing I am not prepared to pay a five year investment just to monitor my heat pump…

There are quite some 3 phase meters around with modbus, you will need a modbus to usb or TCP gateway tho.
And those will be around 80-120 Euro’s
There is no real cheap and safe way tbh.

I have the 6ch esp32 and IIRC when researching it had a very high level of accuracy compared to other boards. That said an ADS1115 I believe has a 4 ch input and can be used with esphome and ct clamps.

There is also iotawatt IoTaWatt Stuff – Genuine IoTaWatt hardware and accessories but I have no idea if it is economic in the EU.

Just use 3 pzem004t v3’s with a esp - accurate and cheap.


I have iammeter’s 3-phase module. Works great. But it’s not cheap. I don’t think you’ll get one under 100€…

The shelly 3em is EUR82.50 from Shelly, compared to EUR115 from conrad.

3 units pzem004t v3 should arrive at your destination for around $20-30 from far east :airplane:

Thank you all for your suggestions.

An esp with 3 * pzem004t seems to be the affordable alternative to the CircuitSolution package, a bit more work compiling the bits and pieces, but not too bad.
There seems to be some confusion wrt if the diodes are needed with the pzem’s depending on which forum and discussion is followed, but I will learn en-route.

Amm… that’s without VAT. Official web site says 99€ incl.VAT (of course it depends where you live, it can be even bigger). Plus P&P and you’re over 100€… But it’s still cheaper than Conrad, i agree.


What are you trying to tell us?

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Keep in mind that the Shelly 3EM is build for 3x 230V energy grid and not for 3x380+N which has also 230V between N and L1,L2 and L3

Yes but you are measuring each phase against N which means you are measuring 230v not 380v.

Also for 230v phase - N the phase to phase voltage is 230 * sqrt(3) = 398v not 380.


Hm… is there any country, who has 380V Lx-N voltage? I can’t remember one…

Shelly 3EM is made for 3x 230V Lx-N voltage, and 3x400V Lx-Ly voltage. Yes, it’s 400V, not 380, as nickrout already said. It USED to be 220V Lx-N and 380V Lx-Ly, but it’s looong gone…