Here is the schematic

I made an adaptation to my 3rd powermeter.
The used wemos D1 mini has several unused ports, so I added a transistor + relay to switch the output power.
Now I can switch on or off the output power by Node-Red.

In the software of Karl Hagström I see the line: if ((U > 195) && (U < 253) && (P >= 0) && (P < 4000)) // ignore spurious readings with voltage or power out of normal range { I adapted this line a little, in the Netherlands the voltage can be 230volt -15% +10% Perhaps this can help you.

I ordered three powermeters and all three have a different printed circuit board. The 1st and the 3rd with spi interface, the 2nd with serial interface.
For the 3rd powermeter I made a pcb for the wemos and power supply, it just fitted in height.

Indeed, that's what I meant.

I was just interested in volt, watt an frequency. kWh will be calculated by the Node-Red system.
With the finishing of the software I stopped investigating the power meter.
But I like to hear from you if there are more possibilities with the power meter.

You're welcome.
As I said, I am not working with domoticz, but with Node-Red.
The calculation from watt + time to kWh is done in a Node-Red function. I think in Node-Red the time is quit accurate, in wemos not.

Thanks, it was nice to do.
I will share the code here.

Well, after a couple of days working on this second power meter, I have it working. The first thing I did, was to find out which chip was used. With the help from circuitsonline https://www.circuitsonline.net/forum/view/message/1914040#1914040 it turned out that it was a V9261F chip from Vango ...

I ordered a second power meter, because I wanted to do some more tests. I received the same as littlewouter. It looks like that there is a redesign of the pcb of the power meter. The pcb is much more simple. But for me it is unclear which chip is used. Tomorrow I get a separation transformer and ...

Unfortunately I am not familiar with the C compiler for the software, so I could not use the software from Sweetpants, sorry for that. Normally I work with Arduino ide and the last couple of month I use the wemos D1 mini. I wanted this wemos D1 mini build in in the cheap Chinese power meter and ...

Still no reaction from Sweetpants, hope he will come back to this topic once more.
Not possible to send a pm to Sweetpants by myself . . .
edit: after this post reply, I can

I also want to make this power meter wireless.
The ESP8266 version that I want to use is the Wemos D1 mini.
Hope I also can get the code.
I will send a pm to Sweetpants (edit: not succeeded)