A. Our smallest panel width is 152mm, and the widest is 750mm, although with larger louvre panels, we do sometimes go wider, but void the warranty with your permission. Generally, a window looks best with four panels, two opening as pairs either way. A 3 window bay, however, will usually have two panels on the smaller side windows and 4 in the centre. All panels will open away from the middle.
There are as many exceptions as there are norms. For instance, a wide window with three panes of glass, i.e., 1600mm wide and 1000mm high, would have six panels; three folding either way, or if you are only going to open them to clean the windows, you could easily have just three panels. The Americans never open the shutters, only the louvres, so the design has large panels.
A lot of the time, you will have to consider where the panels are going to fold back to and if there is enough room for this to happen. This is also true where you are fitting inside the reveal next to the window, and you will not want the shutters, when open, to protrude into the room too much.
We would not recommend hanging more than three panels from a single batten hinged together unless they were not going to be opened apart from window cleaning and were resting on the sill or doorstep. As the maximum recommended width of our panels is 550mm, you may say that this equates to 3300mm maximum width, but it would be asking a lot of the batten to hold panels of this width and weight without sagging at a later date. So quite a lot of common sense is needed to achieve a good installation.
For partitioning or for large windows where tracking is needed at the top to suspend the panels, you will really need an even number of panels, or they will look odd and not hang from the track properly. Ideally, eight panels or 12 panels for very large openings is best, and you can split them in the middle or take them all to one side.
In summary, the window will normally dictate the number of panels. If the window is split into two halves, you would either have 2 or 4 panels, and it follows that if it is three panes, then three or six panels will suffice. The vertical dividers of the windows are where the vertical stiles of the shutters should ideally be.