Abstract: The invention relates to a device for stiffening and sealing a solar collector, providing protection against breakage and secure sealing of the connection area between an extruded flat plate solar absorber and fluid-inlet and -outlet collectors. The device comprises: a support profile for stiffening the extruded flat plate absorber and the fluid-inlet and -outlet collector, formed by open cylindrical modules together with two parallel plates; and a tray, made of plastic reinforced using fibreglass fabric, for sealing the connection between the extruded flat plate solar absorber and the fluid-inlet and -outlet collectors in such a way as to maintain said elements as a common or single-piece element.