Yes exfarmer,
if you have grid power available batteries can't compete. Seems like you have much the same pricing system we have here. Nothing under 6kw is worth the effort. With your $3299 you should pay for it in 3.5 years but might be quicker in WA because of the sunlight. If you can manage to export 20 kwh a day you won't have to pay a power bill, that is the break even point. That also depends on your usage which should be around or under the 5kwh figure. We have 3 fridges running and we are around the 4 mark per day.
