If a building permit was required, after your system is installed your local permitting agency, usually a building or electrical inspector, needs to inspect and sign off on your system.
If you have a grid-connected PV system, in most cases your utility company must inspect your system before it is turned on.
Depending upon the inspection, your system may need corrections or modifications to satisfy the inspector’s requirements. Corrections are fairly common in the construction business, so don't be alarmed if they are requested of you and your installer.
A copy of the building permit (if it was required) showing final inspection sign off, homeowners insurance, and (if installing a grid-connected PV system) a recent utility statement showing electrical service at the installation location are required to obtain a rebate from your utility or other funding agency, and for warranty programs.