[Solarpanels on building with flat roof]

Hi 

i am a newbie at this program and i am having a hard time getting on the upper edge of a flat roofed building. 

i seems like a can only apply PV modules on the walls.

what am i doing wrong.

i need to place pv modules on the roof

thanks in advance for your help

[Solarpanels on building with flat roof]

Hi There

I am having a hard time placing PV-modules on a flat roofted building. It seems like i only can apply pv modules on the walls, and not the roof? 

What a my doing wrong?

i cant get on the upper edge of the building!

thanks in advance (the newbie)