"No expenditure relating to a solar panel or other property installed as a roof (or portion thereof)"
I think the above phrase is what is hanging you up ... the words say AS A ROOF and not THE ROOF ... for instance, my bank has installed solar panels over the drive thru lanes in lieu of a traditional roof so just because the solar panels act as a roof does not exclude them for the credit. Also a client had the panels installed AS AN EXTENSION to his Garage roof which provided a shaded driveway for the cars ... it was not ON the roof it was the roof ... so the installation of the pillars to support the solar panels were part of the solar costs even though they became their own structure. Another client had the panels mounted on 8 foot poles which made a lovely Gazebo in the backyard ... again it became it's own separate structure.
