The sun-path module allows you to visualise a sun-path diagram in Bleners 3D viewport as well as synchronise the animation time-frames with the time and date for your particular location. This allows provides an overlay sun-path to assist with modelling/designing in Blender as well as the ability to add lighting objects (or any object) to the animated sun-path so that you can render scenes and visualise shadowing using either the Blender renderer and/or the Blender Cycles unbiased renderer for very beautiful renders.