South Australia has one of the highest electricity rates in the world
Logic suggests in this part of the world you must consider Solar panels
These are rough and perhaps inaccurate calculations
From what I gather , by having solar there is a potential to save something like 50-75 % on electricity bills
For someone who has quarterly bills of about $500 that equals $2000 per annum , so the savings might be about $1000 to $1300 per year
A system of about $5,000 would pay itself off an average of perhaps about 4 years [ this is an estimation , but need to consider all the variables]
So in theory if panels shave off a bill from $2000 a year to say $1000 [that being a 50% reduction] how much more can a battery save the consumer per year ?
As amber fluid said, without a battery the savings have a ceiling unless you shut all the power down when the sun goes down. We have had solar since January and so far based on two bills the savings are 30-40%, not 50-75%. But it might depend on your own situation, maybe you can get more.
With a power bill of "only" $500 a quarter you may not need a $5,000 system though.
They say a payback period of about 4 years and for us so far that is how it looks. So for you to save $700 per year ($2,000 x say 35%) that would suggest to me using the back of a pasty bag that you only need a ~ $3,000 system.
Whoever you ring for a quote will do all this maths for you but in my experience they may embellish the possible savings.
With a battery however based on my tracking of what we send off to the grid unused during the day from the panels versus what we then use at night I am hopeful we can get the bill down to almost nothing with a battery. I say hopeful because we signed up for a battery that will be installed in the next few months (via AGL's suburban battery farm concept with a discounted battery).
It is currently really frustrating to see us use the same amount of power when the sun goes down that we export during an average day unused.