we can't see your return. but you are correct. the Solar Credit can reduce your taxes to zero but any excess should not have been refunded. what did your actual return show? review the second page of the 1040 (especially line 35 and 35a) and form 5695 - the carryover should be on line 16. then if you don't see a reason for the refund contact the IRS for an explanation. for example, if you had $4,000 in withholding taxes and your liability was reduced to zero that would be refunded.
