You can claim the credit when the solar panels are installed on your Home.
IRS Form 5695 Residential Energy Credits Instructions - https://www.irs.gov/pub/irs-pdf/i5695.pdf
Home. A home is where you lived in 2021 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
