Solar mounting / racking systems are often seen with long rails (e.g. c-post, t-rail, etc), where the solar PV modules rests on. The solar PV modules are locked down to the railings with clamps. These railings can be extended to allow solar PV modules to be inclined to better receive sunlight. There are mounts specially designed for pitched roofs, ground mounted and flat roofs. Though as technology grows, we’re seeing more carport mounts and floating solar mounts too.
Solar racks are then retrofitted on rooftops (slated, flat concrete, metal deck, etc) with additional accessories to help hold the railings on the roof. If required, foundations are created,or ballasts are added to get sufficient weight to hold down the solar racking system.
A civil engineer working along with a solar PV system designer would determine with wind load and sun path in order to propose the best orientation and a correct solution for a solid solar mounting / racking system.