Here in western Australia we are charged approximately 26 cents for every kilowatt of power consumed. We receive 7 cents for every kilowatt of power we export back into the grid from our residential solar systems.
The key to next to nothing energy bills is to install the largest system your network provider will approve. 6.6 kilowatts of panels feeding a 5 kilowatt inverter is the maximum currently that you can install and still receive the 7 c/kilowatt export payment. Subject to approval of course.