For a set and forget system, the north angle should be at your latitude. Brisbane is 27 degrees or so.
If you can adjust them, as sounds like in your case, the adjustment range is 27 degrees +/- 23.5 degrees so it will vary from 50.5 degrees in winter to 3.5 degrees in summer. 27 degrees is for the equinox at September 21 and March 21.
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