Single Row of Towers
This is the most common arrangement and is great for running along a fence or wall. Towers can be any height and the frames can be easily made from wood or steel. Wood frame models and plans are in the "How to" Tab of the website.
The main disadvantes are it needs to be well anchored as it is on the tipsy side, and if you are doing a lot of towers, it does not make good use of aisle space.
Double Rows of Towers
This is the preferred layout for large tower installations. The frame is typically 24-30" wide with a 24-30" aisle between each of the frames. Towers can be any height and the frames can be easily made from wood or steel but for commercial installations, steel is generally preferred. Since it is wider, this design is also more stable, though footer anchoring is still recommended.
Towers can face to the interior of the frame (for artificial lighting) or face the sun. If using the sun orientation, you can stagger the towers slightly between the 2 rows.