Abstract: The present invention relates to a panelized lightweight control enclosure, capable of being substantially manufactured before installation for housing power system devices of a power system substation. Specifically, the control enclosure is comprised of a structural frame including a plurality of vertical posts, a base, a plurality of side panels for forming the walls thereof and defining an interior space therein for housing the power system devices, and a roof for covering the interior space. The structural frame engages and provides support for the side panels and roof. To facilitate engagement between the frame, side panels and roof, the control enclosure includes a plurality of tongue-and-groove fittings. As a result, the present invention control enclosure may be constructed at and/or transported in an assembled state to an installation site.