If you want to place a solar array behind another array, you would need to ascertain whether the front array will cast a shadow on the rear array.

There is a trigonometric formula to calculate how far the shadow of the front array will be cast at midday during the winter solstice.
Winter of course is when the shadow is the longest and longer in the morning and afternoon than at midday.
But to calculate the length of the shadow at any time of day and from that to calculate how far behind the front array you need to be gets very complicated, mathematically speaking.

You would need to calculate how far south (in the southern hemisphere) the eastern corner of the front array casts on the rear array in the morning and how far south the western corner of the front array casts on the rear array in the afternoon, taking the width and placement of both arrays into consideration.

To help to figure this out, we have produced a series of tables covering latitudes from the northernmost tip of Queensland down to Tasmania.

Winter Shadow Digram is an illustration to help understand the tables

WinterShadow is series of tables with the for various latitudes.

WinterShadow 42 degrees.
WinterShadow 38 degrees.
WinterShadow 36 degrees.
WinterShadow 34 degrees.
WinterShadow 32 degrees.
WinterShadow 30 degrees.
WinterShadow 26 degrees.
WinterShadow 22 degrees.
WinterShadow 18 degrees.
WinterShadow 14 degrees.
WinterShadow 10 degrees.

There is one called NimbinWinterShadow.pdf which is the exact latitude of Nimbin.