There is a difference between the values on your portal or inverter and the values from your energy supplier. On your inverter you can see the production of your solar panels and your energy supplier shows the energy fed back into the grid.
The inverter shows the energy production. This produced energy is first used up by devices in your home, for example your fridge, lamps, washing machine and dishwasher.
The energy that you do not use directly will be fed back into the electricity grid and will then pass the smart meter. This meter thus only measures the energy going into the grid. Your energy supplier therefore only knows the amount of energy fed back to the grid, not the production of your solar panels.
The difference between your produced energy and the energy fed back into the grid is the energy you used during the day. This means you directly used the sustainable energy you generated yourself!