Thanks for the replies!
Unfortunately, there was no discussion that the price was reduced due to his claiming of the tax credit... I believe he sold to us, passed the cost on to us, then claimed the tax credit as well. I also believe it is wrong for him to claim the tax credit, the rules are murky obviously, but one of the clear eligibility criterion is that the house where the solar is installed needs to be a primary or secondary residence. The home is a new build and was never his residence. There are credits builders get for building energy efficient homes, under 45L, but it seems to me 25C and D, should be for home buyers/owners...
