Yes, you can. The only issue is when you can claim the
credit.
According to the Instructions for Form 5695,
For purposes of the credit, costs are treated as
being paid when the original installation of the item is completed, or, in the
case of costs connected with the reconstruction of your home, when your
original use of the reconstructed home begins. Costs connected with the
construction of a home are treated as being paid when your original use of the
constructed home begins. If less than 80% of the use of an item is for
nonbusiness purposes, only that portion of the costs that is allocable to the
nonbusiness use can be used to determine the credit.
Based on what
you're, stating it appears as if the costs will be treated as being paid in
2018, if they weren't connected with any reconstruction of your home, or the
construction of your home, since that's when the installation was completed.
