Convert Watts to kWh for Energy Meter?

I have a house energy meter that I read send the data to HA using MQTT messages. It just sends the number of watts being used every 5 seconds. I am trying to use that in the Energy dashboard in HA (HASIO, running on a raspberry Pi, latest version).

In an attempt to get this to show up in the energy meter, I created a Helper of the type: “Add Riemann sum integral sensor”

I set it to hourly. I add this in the Energy Meter in Home Assistant. but it shows an error that this is “Unexpected Device Class”. Is there a setting that I should look at to determine what is going wrong?

Thank you

[EDIT] I am not sure if this is an error that I need to worry about. If I just ignore it, the energy meter screen does show the bar graph, with data that does seem to match reality.

That “energy” meter (actually, it’s a power meter) should have “device_class: power”.