Architectural panel systems, and methods of installing architectural panels on support structures. Architectural panel systems can include support brackets attaching architectural panels to a support structure, first fasteners attaching the support brackets to the architectural panels, and second fasteners attaching the support brackets to the support structure. Methods of installing an architectural panel system can include attaching architectural panels to support brackets with first fasteners, positioning the support brackets on a support structure, and attaching the support brackets to the support structure with second fasteners, for example, that extend through the support brackets. Architectural panels can include interior cutouts that pass sunlight to form aesthetic patterns of sunlight and shade in an occupied space. Support brackets can include opposite sides, four quadrants, through holes containing studs extending from one side of the plate, a center hole, or a combination thereof.