Solar feed in tariffs and what they are compared to power used from the grid are covered here:
The daily supply charges are a fixed component of one’s electricity bill and relates to the cost of having the ability to draw electricity from the grid. It is independent of the amount of electricity used. I suspect that you have misread your bill as:
rates will be ‘per day’ and not ‘per kWh’. Origins charges included supply charges are outlined here:
