Bi - fold doors are great we have them in our home and love them, being able to bring the outside in is perfect on the rare summer days we get but it becomes a little bit tricky when you're trying to keep the outside out!
Due to the size of most bi fold doors there are few blinds that can cover the window in one blind, the main options being Vertical blinds which are not to everyone's taste or a tracked shutter which are not to everybody's budget, so this means a single blind for each panel, any bifold door with more than 2 panels then runs in to the problem of not being able to have control cords hanging down on the centre blinds
Solution 1: Intu pleated blinds are designed to fit inside the frame of bi fold doors and are slim enough to allow the doors to operate without hindering opening of the doors.
Solution 2 : Motorize roller blinds, From blackout, sheer to dual shade rollers these have been or most popular option for bi fold door blinds.