"So, that fact that I’m a 100% service connected disabled veteran receiving a nontaxable income should have no bearing on weather or not I get the tax credit."
It's true that the solar tax credit will have no benefit for someone who has no taxable income. The credit is "non-refundable", which means that the most it can do is reduce one's tax bill to zero. It cannot result in cash back to the taxpayer.
That's just the way that Congress wrote the law.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.