Yeah Luigi you probably right about that penta-problem... but soloing is not an opposite of improvising... good guitarist here and there just improvise their solos in studio... our friend page did it alot, though it doesnt sound good always...
Another important thing is to add stuff to the solo... you are a guitarist, not a machine try to add pull offs slides and other stuff like that
about the D that was posted by Jay: yeah that's probably a thing you can do... you should learn all the basic modes and scales
and then it will be easier... offcourse as Luigi said playing the scale up and down is not soloing but you should be able to do this, to get speed... your fingers should find the right frets even when your eyes closed and then you can break the scale