You can see what happens to the sun's shadowing when its placement is far to the right.  Shadows extend out and away from the house moving to the left.  Details of the roofs eves can be seen in the shadows edge.  

 

The main lesson here is that shadowing is not by accident but a technique based upon rules.  Failure to recognize and use these rules will adversely impact your drawings and illustrations.

 

More importantly, shadowing impacts the characture and dynamics of your work.  It enhances the three dimensional quality of your creation and when used properly can improve dramatically the over-all visual appeal.