I think there are a couple of issues here.
1. Turbotax's current version of form 5695 is broken. It denies all credits unless you say it was your main home. This is incorrect, because some credits are allowable for other dwellings you use as a residence even if it is not your main home. I have seen an unofficial fix date of Feb 23.
2. However, a credit for windows is only allowed if the windows are installed on your main home (your principal residence).
If you answer "yes" for principal residence, you need to click past the solar credits and keep going. If you answer "no" for principal residence you aren't eligible.
