the instructions for the 5695 explain how it works

Qualified solar electric property costs. Qualified solar electric
property costs are costs for property that uses solar energy to
generate electricity for use in your home located in the United
States. No costs relating to a solar panel or other property installed
as a roof (or portion thereof) will fail to qualify solely because the
property constitutes a structural component of the structure on which
it is installed. Some solar roofing tiles and solar roofing shingles
serve the function of both traditional roofing and solar electric
collectors, and thus serve functions of both solar electric generation
and structural support. These solar roofing tiles and solar roofing
shingles can qualify for the credit. This is in contrast to structural
components such as a roof's decking or rafters that serve only a
roofing or structural function and thus do not qualify for the credit.
The home doesn't have to be your main home.