Hi 
!
Have a look at the documentation, it’s all there. Fronius - Home Assistant
It’s an energy dashboard - it uses energy. I guess probably because many integrations don’t provide live power readings and would therefore not work. Also keep in mind that the energy dashboard is populated only every hour. It’s for statistics.
For live controlling of some application you can just use an automation with power entities if you like.
Oh, and there is also a great, very detailed thread about exactly this: Howto: Fronius Integration with battery into Energy Dashboard