Abstract: The solar energy-collecting architectural enclosure panel includes outer and inner plates which are mutually facing and joined by a leak-tight joint along a closed perimeter separated at a distance from perimetric edges of the panel. The outer and inner plates include within the closed perimeter hollow conformations to form a circuit for a heat-carrying fluid with an inlet and an outlet. Adjacent to opposite longitudinal edges of the outer plate there are first longitudinal stiffening configurations and adjacent to opposite longitudinal edges of the inner plate there are second longitudinal stiffening configurations configured to rest on transverse elements of a structure. The outer and inner plates are furthermore joined by a mechanical connection in expected maximum bending stress areas adjacent to the opposite longitudinal edges of the outer and inner plates.