A long-side frame piece has a cylindrical portion. The cylindrical portion is formed from one side end along the direction in which the long-side frame piece extends to the other side end. The cylindrical portion has threaded holes. The threaded holes are provided inside a through hole. Screws are inserted in the threaded holes. A short-side frame piece has a plate-shaped portion. The plate-shaped portion covers the end of the cylindrical portion in the direction in which the long-side frame piece extends. Openings are formed in the plate-shaped portion, through which pass the screws inserted in the threaded holes. The plate-shaped portion has a cutout exposing a portion of the module body from a first surface toward a second surface, formed closer to a first direction side than the threaded holes of the through hole.