I have just completed a somewhat deep dive into using the PZEM-004T for monitoring electrical branch circuits, HVAC and other electrical loads. I have written up a many-pages document with my results, but I thought some people might like to see the super-short results.
It works as intended, although the software setup is moderately complicated.
It works with the Arduino libraries for it, and with ESP family controllers.
I got it running with MQTT and Node Red to save monitoring data.
Here's the Bad Thing: the PZEM-004T module does not meet USA and/or other international safety standards and cannot be simply modified to do so.
Second order Bad Thing: The PZEM is not safety laboratory listed/certified; this means that (at least under USA, state, and local laws) it cannot meet the electrical codes for buildings; that means that most insurance policies will not cover fires where they attribute the fire to electrical causes and the PZEM is present.
The document has some in-depth commentary about the safety issues, and also about the controller IC, parts ratings on the module, modifications, and so on.
If there is enough interest, I'll post a link to the document.
I realize that this is late information, as the PZEM-004T is fairly old news. But someone may be able to use it. The PZEM is itself becoming obsolete. The Vango Technologies V9881D controller chip in it has been discontinued, although there are stocks of chips available. There is a successor chip, the V9981, which might do much the same thing.