A glazing panel system is provided with improved glazing panels, retention clips and/or U-shaped connectors. The retention clip may engage the glazing panels at locations lower than top ends of the upstanding seam flanges. In one embodiment, an internal U-shaped connector is positioned to engage the seam flanges while an external U-shaped connector covers the internal connector and the seam between adjacent glazing panels. The retention clips may be formed with an upper transverse portion that is movable relative to the base portion of the clip to accommodate panel expansion and contraction. Also, a thicker plate or portion may be provided at a top flange for the retention clip to provide increased resistance to uplift loads trying to bend the flange.