I found the answer in tax specialist Lane's response here:
https://www.justanswer.com/tax/8weid-solar-does-tax-liability-mean-getting-solar.html
That's good news, looks like I will get a big refund.
The vast majority of articles on this topic are terrible. They make it sound like a nonrefundable tax credit will never get a refund. But actually if you prepay more tax than the total tax liability (e.g. through the normal payroll withholding) there can in fact be a refund because of the nonrefundable tax credit.
