You can take the credit for your home, but not your parents'.
This, from the instructions for Form 5695, Residential Energy Credit:
Who Can Take the Credit
You may be able to take the credit if you made energy saving improvements to your home located in the United States in 2018.
Home.
A home is where you lived in 2018 and can include a house, houseboat, mobile home, cooperative apartment, condominium, and a manufactured home that conforms to Federal Manufactured Home Construction and Safety Standards.
You must reduce the basis of your home by the amount of any credit allowed.
Main home.
Your main home is generally the home where you live most of the time. A temporary absence due to special circumstances, such as illness, education, business, military service, or vacation, won't change your main home.
