I contracted to install solar panels on my home in 2016, but didn't start making my payments to the finance company until 2017. Can I claim the deduction on my 2016 taxes

[mtbike2011]

They started working on my solar system in 2016, getting permits, design, etc.

[hbl3973 · Accepted solution]

Yes.  The instructions for IRS Form 5695 state:

Nonbusiness Energy Property Credit
(Part II)
You may be able to take a credit equal to the sum of:
1. 10% of the amount paid or incurred for qualified energy
efficiency improvements installed during 2016, and
2. Any residential energy property costs paid or incurred in
2016. 

As you incurred the debt, you qualify for the credit assuming you would otherwise qualify.