I think the problem is that the following IRS Statement offered, in response to the question, is a double negevite: "No costs relating to a solar panel or other property installed as a roof (or portion thereof) will fail to qualify solely because the property constitutes a structural component of the structure on which it is installed." My spouse & I read this as "no costs relating to....will fail to qualify" therefore it sounds, to us, like the roof qualifies. Hopefully Turbo will weigh in.
