This same question is addressed in another thread (https://ttlc.intuit.com/community/state-taxes/discussion/re-could-i-claim-the-30-federal-solar-tax-c...), and I believe that @CA Solar Expert and @BMcCalpin were spot on in their analysis of the underlying tax code (from which the wording in the instructions that is being used to justify including the roof is pulled). Their conclusion, and my own: the roof would not qualify unless you're considering solar shingles or other such solar harnessing material as the roof itself.
