Depending on the size and type of solar panels, as well as the wattage of the appliances in your house, you would need approximately 5-8 kW of solar panels to power an average Australian home. This number can vary depending on a number of factors such as the climate and location of your house.
It's important to keep in mind that installing solar panels does not mean you will be completely self-sufficient; it's likely that you will still need to purchase some energy from the grid, especially during peak hours. However, by installing solar panels you can offset a good portion – or even all – of your energy usage, which will save you money in the long run.