The FEMA Flood Map Service Center is the official public source for flood hazard information produced in support of the National Flood Insurance Program. You can search official flood maps by address, place name or coordinates, access the flood hazard products for a community, and download what you find. It is free.
FEMA notes that flood maps are updated regularly, so a map downloaded or printed today may not remain current.
How it gets used on a real project
Flood zone designation reaches a solar project through several doors at once. It changes what insurance costs and whether it is available, it drives civil design and equipment elevation requirements, lenders ask about it in diligence, and in some jurisdictions it affects permitting outright. All of that is cheaper to know during site selection than after.
The one-minute version: pull the parcel before the site walk. A Special Flood Hazard Area designation does not kill a project, but it does change the cost and the design, and finding out late is how a budget moves in the wrong direction.