Requirements for energy integration

Hi,

I configured several sensors via REST from my energy meters.

This is what it shows me as entities in the dev-tools:
entity:

sensor.ewa_counterreadingexport
EWA.CounterReadingExport 

state:

67.010483

attributes:

unit_of_measurement: kWh
device_class: energy
friendly_name: EWA.CounterReadingExport

But I cannot select them for the energy dasboard, neither for the net nor for single devices.

More than 2h past after adding them.

any ideas?

regards
Daniel