[nagisa]

The port/protocol originates in Netherlands and is getting widely implemented across the EU. It is really nice that the port provides power (esp. in recent versions) for an ESP, so you don't need to worry about bringing power to where your meter is (which may be outdoors.)

[microtonal]

Yeah, P1 has been around for a decade or so in the Netherlands. If don’t feel like setting up an MCU yourself, Homewizard Energy is pretty good. I don’t use their services, but you can enable a simple API on the local network that gives you a JSON representation of the ‘telegrams’ that come out of the P1 serial port.

https://www.homewizard.com/p1-meter/

[juahan]

Oh yes, now I remember reading the P1 spec and it does indeed say that it has been in use in the Netherlands for many years already. In Finland we also call it the HAN-port or the H1-port. Also, I must clarify that it uses RJ12, not RJ26 which I don’t even think exists.

[ragebol]

The HomeWizard stuff is great. They also make a water meter, separate kWh meters in 1 or 3 phase and smart plugs.

If you have a subscription to their service, they can be programmed to eg turn on when there's excess solar power etc. And integrates with HomeAssistant.