If you want to include your smartmeter chances are you have a model which offers an optical bidirectional Link at the front side. One of the best options are buying the kit HICHI offers. It consists of a round magnet to attach the sensor to your smartmeter (no tools needed), a ESP8266 and the IR sensor connected to the ESP. The ESP is preflashed with the latest Tasmota software which makes it very easy to integrate the smartmeter and its readings into a smart home or sending the readings to a MQTT server.

You will need only an ordinary USB loader (Micro plug).

But the whole thing is missing a good case so I designed one, it consists of the case and a cap to close it. I had to look for the right USB micro cable to fit through the hole I left but now it looks pretty sleek.