Australia, being in the Southern Hemisphere sees the sun rises from the East via North in the middle of the day and sets in the West. In the Northern Hemisphere the sun rises in the East via the South and sets in the West. There is also a variance throughout the seasons in solar radiance because of the solar solstice. A solstice is an astronomical event that occurs twice each year as the Sun reaches its highest or lowest point relative to the equator.
In short all roofs can be suitable to install solar, except a southern facing roof. In Australia, now that the Net Metering is the norm, it is very important that the solar panels should be located taking your own electricity consumption pattern into account. For example if you use most electricity in the morning and during the earlier part of the day then install the panels on the eastern roof. If you after the most solar electricity output from mid morning to early afternoon install the panels on the northern roof. If your kids come home at 3pm and turn on all appliances, or you want to offset as much as possible your air conditioner use late in the afternoon then you want as much solar electricity as possible in the afternooon. Therefore install the system on your western roof. Or if you get a 4 or 5 KW system you can put one solar module string on the northern roof and one string of panels on the eastern or western roof to get the whole day supplied with solar power.
While an eastern or western roof installation will produce between 5% and 15% less electricity than solar panels facing true north, the time you require the electricity and the aesthetic look of the solar system on your house should also be an important consideration when deciding the final position of your panels.
Ask your installer for advice as to the best possible solar panel location.