A U-shaped spacer element supporting and retaining a photovoltaic panel assembly spacedly over a rooftop corrugated sheet; one shorter side leg thereof having an oblong bore, the other side leg having an intermediate ridge section. A screw engages into the ridge web and axially clears the shorter leg, anchoring the main body to the supporting rooftop frame elements through the corrugated sheet. The ridge section conformingly abuts against a longitudinal rib of the corrugated sheet. An L-shape bracket inner leg abuts against the main body short leg, the bracket outer leg abutting sideways against a registering portion of the photovoltaic panel assembly. A second oblong bore is made into the outer leg and extends parallel to the plane of the main body base leg. Two bolts engage the oblong bores and adjustably interlock the L-shape bracket to the spacer element main body and to the photovoltaic assembly.