A little late to the party, but....
If you have any tax withheld during the year, you will definitely benefit from the solar credit. The credits will offset what you owe, before accounting for the withholding. If your computed tax, based on your taxable income, is less than the credits then:
1. your taxes will be zero and all your withheld amount will be refundable and
2. any solar credits in excess of the computed tax will be carried forward.
This is looking only at the solar credit.
