Are there any costs associated with approvals from local government or electricity provider and how much?

Are there any costs associated with approvals from local government or electricity provider and how much?

Possibly, you would have to check with your local council.
If you decide to proceed with batteries, the installer will need to get an approval from the DNSP to install your battery system and there may be a cost involved as part of this which you would be responsible to pay. Check with the supplier during the quoting process for an accurate idea of how much this may be.