Thank you. I ran your experiment, zeroed out the 8,414 solar expenditure (2,188 credit), and the refund stayed the same. Then compared the results.
After a lot of tracing have deduced that the credit adjusts as necessary to meet my Tentative Minimum Tax (form 6251, line 9), and the balance is carried forward. The calculations go through 5695, 8801, and Schedule 3, but the effect is just to enforce the 6241 min tax constraint.
Ugh. No solar tax credit for me. What confuses me is that I'd not heard this mentioned anywhere, and while my income is higher than average, approximately $300k, I would expect there are a lot of solar customers with even higher incomes and I assume they would have known and squawked about this.
Thank you again for the good debugging strategy.
