In order to work with HA Energy Dashboard, energy output needs to have a state_class of "total_increasing". This might require the addition of a persistent state value, or perhaps an additional value other than just what the API returns.
Actually, you just need to change the state_class of the energy output sensor in sensor.py from SensorStateClass.MEASUREMENT to SensorStateClass.TOTAL_INCREASING.
See https://community.home-assistant.io/t/energy-dashboard-last-reset-missing/406733
In order to work with HA Energy Dashboard, energy output needs to have a state_class of "total_increasing". This might require the addition of a persistent state value, or perhaps an additional value other than just what the API returns.