Adding a daily charge is something that can be done in your tariff / utility meter setup.
Here’s what I’m using to calculate the cost of import / exported, then calculate the correct tier (peak / shoulder / off-peak) that should be used for that time of day and then add in the daily connection fee and work out the current daily cost for power for that day.
I’m using Solar Analytics as the data source for kW etc, but just update it to whatever your using (which btw should be the cumulative import / export costs, not the daily/todays like I have…side issue being flagged atm for SA integration to fix).
This is based upon original code by SgtBatten, and I still have to get a chance to also work up a version that supports peak / shoulder / off-peak + demand based fee (charged based on the highest 30min kWh consumption during peak hours for the month x a per kWh demand fee).