@BillM223 , Thank you for the reply.
The difference in reroofing with the old, built up roofing over the Homasote and the restructured roof is not insignificant...about $30,000. This included building new cross beams, adding the insulation material, plywood sheeting, layers of tar paper, fascia replacement (due to the increased cross section), fabricating and attaching the panels. Basically, a new roof had to be built on top of the existing structure to reinforce it and properly distribute the weight.
Since I have estimates for both, I'll deduct the cost of a straight replacement roof from the cost of the structural enhancements and use the difference as part of the credit.
By "entire amount" I was referring to the entire cost of the reroof project vs. a percentage of the cost of the project (the percentage of the roof that directly supports the solar panels).
If I were to use that approach, that would mean either 100% of the reroof costs or approximately 66% of the cost since that is the portion of the roof that is directly supporting the panels. I would have to directly measure the panels vs. the roof to get the exact percentage.
