LCOS calculation

Hello SAM team,
I have a doubt about how to calculate the LCOS. In the following image you can see the annual operation of the storage system. In a general battery system, I am charging the batteries by buying energy from the electrical network, and from the photovoltaic surplus of the installation.



The annual cost of the storage system together with the discharged energy determines the LCOS. However, I don't understand why the annual cost of charging the batteries from the grid is zero, when I am buying energy to charge the batteries at certain times of the day.
The other thing I'd like to clarify is how you calculate the annual cost of uploading from the system. Does this cost refer to the annual degradation of the batteries?

Thanks in advance. Best regards,

Orlando