I agree with @Opus 17 you can not claim the credit for federal purposes.
from code section 25D
(2)Qualified solar electric property expenditure
The term “qualified solar electric property expenditure” means an expenditure for property which uses solar energy to generate electricity for use in a dwelling unit located in the United States and used as a residence by the taxpayer.
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could your parents use the credit? if so, the way I would advise this be done is for you to make a gift to them of the money to pay for the system.
