Please clarify. The section 25D credit is only available for your residence, not your business. There are different credits for businesses that I don't know anything about, but I don't think they are 30%. For the residential credit, your basis is reduced by the full amount of the federal credit, plus the full amount of any state credits or utility rebates.
If you installed the solar panels on a property that was 50% a residence and 50% a business, then you only claim 50% of the cost for the residential 30% credit under section 25D.
