Abstract: A solar cell panel installed in an outer wall of a building structure for generating power from front and rear surfaces. A panel package including double-side power generation type solar cell panels or a group of solar cell panels arranged across a plurality of stages in a height direction is supported by vertical members supported by arm members overhung in a structural out-of-plane direction from an outer wall face having an opening and juxtaposed with an interval in a structural in-plane horizontal direction of the outer wall face while the panel package faces the outer wall face. The panel package is arranged between overhang members protruded side by side in a height direction to the exterior side of each vertical member and juxtaposed in a structural in-plane horizontal direction, and upper and lower portions of the panel package are held by the overhang members juxtaposed in a height direction.