@Kapolei - did you enter your income yet? the solar credit is what is called a 'non-refundable credit', which means it can be used to reduce Line 18 of Form 1040, but the result can not be less than zero.
if you didn't enter your income, then TT shows you have no tax liability (i.e. Line 18 = 0) and thus any solar credit needs to be rolled over to next year.
is that the problem? put in dummy income of $100,000; you should see the credit be using on Line 20 of Form 1040.