I have a question. As I understand it the Home Energy Credit is a non refundable credit meaning if my tax liability is 10,000 and I have a 12,000 credit (30% credit) of expenditure on solar panels then my tax liability is zero and I do not get back the additional 2,000. Is this correct?

What if I am due a refund already? Am I still eligible for the full 30% credit?

Also if I spend the money in 2013 but the system isnt installed until Jan 1st how does the IRS know the system wasnt placed into service in 2013?