A system for mounting and supporting photovoltaic (PV) modules includes a frame rail that is formed with a longitudinally extending channel for retaining a plurality of mounting clips, and mounting clamps for anchoring the frame rail to a support base or support structure. Each mounting clamp includes a pair of jaws for engaging along a base portion of the fame rail. The mounting clips are arranged along the length of the frame rail, and are used to support the PV modules adjacent to the frame rails. Module clamps are used to hold the PV modules in place, the module clamps being secured to the mounting clips using elongated fasteners having an engaging end for engaging the mounting clip. The mounting clamps allow the frame rail position to be adjusted in two directions, and the mounting clips facilitate rapid mounting of the PV modules to the frame rail structure.