NOVELTY - Concentrator photovoltaic unit (1) comprises resin lens (2) having outer peripheral portion, which has a circular or regular polygonal shape; and frame-like metal case (6) having opening of at least one of its end portion, which has the same shape as the outer peripheral portion of the resin lens. A center position of the outer peripheral portion of the resin lens and a center position of the opening of the one end portion of the metal case are formed concentrically with each other.    USE - Concentrator photovoltaic unit used in concentrator photovoltaic apparatus (claimed).    ADVANTAGE - Since the single resin lens is attached to each single metal case to form one unit, it is not necessary to bond resin lenses together as in a conventional concentrator photovoltaic apparatus, and even when warpage or distortion occurs in the resin lens due to the difference in thermal expansion between the resin lens and the metal case, the resin lens in another unit is not affected. Since only one resin lens is held in the opening of the metal case unlike the conventional concentrator photovoltaic apparatus, a focus position of the sunlight by the resin lens is hardly shifted in an axial direction, and light collecting efficiency is also hardly reduced. It is also possible to design the focus position of the sunlight by the resin lens taking account of an operating environment of the concentrator photovoltaic unit and a temperature change due to heat accumulation during power generation. By forming the outer peripheral portion of the resin lens to have the circular or regular polygonal shape, the difference in stress along the entire periphery of the abutment portion is reduced. In the abutment portion between the resin lens and the metal case, the stress due to the thermal expansion difference is dispersed, a local stress is hardly generated, and the abutment portion is hardly damaged. Thus, the space inside the metal case can be kept hermetically sealed for a long time. Since the resin lens has the shape bulging out in the direction facing the incident direction of sunlight, even when warpage occurs in the resin lens due to the thermal expansion difference between the resin lens and the metal case, the warpage always occurs in the direction facing the incident direction of sunlight. The focus position of the sunlight by the resin lens can be easily designed while taking account of the operating environment of the concentrator photovoltaic unit and the temperature change due to the heat accumulation during power generation. Since the opening of the one end portion of the metal case is formed to project from the position against which the outer peripheral portion of the resin lens abuts, attachment accuracy between the resin lens and the metal case is not required as compared to a case in which the opening of the one end portion of the metal case corresponds to the outer peripheral portion of the resin lens, and thus, the concentrator photovoltaic unit can be manufactured at lower cost. The heat accumulated during the power generation in each of the concentrator photovoltaic units can be dissipated through the space. Even when the concentrator photovoltaic apparatus is installed outdoors, wind can easily pass through the space, and thus, the apparatus has excellent resistance to wind. Each concentrator photovoltaic unit in the apparatus can be mounted or replaced unlike the conventional concentrator photovoltaic apparatus. The apparatus can be easily handled during installation.    DETAILED DESCRIPTION - Concentrator photovoltaic unit (1) comprises lens (2) made of resin for collecting sunlight; photovoltaic component (4), which generates electric power upon receiving the light collected by the resin lens; frame-like case (6) made of metal having openings at its both end portions and a space; and holding component (5) for holding the photovoltaic component. An outer peripheral portion of the resin lens has a circular or regular polygonal shape. The opening of at least one of the end portions of the metal case has the same shape as the outer peripheral portion of the resin lens. A center position of the outer peripheral portion of the resin lens and a center position of the opening of the one end portion of the metal case are formed concentrically with each other. The outer peripheral portion of the single resin lens is attached to the opening of the one end portion of the metal case to abut against the metal case, so as to collect light onto the photovoltaic component; and the holding component is attached to the opening of the other end portion of the metal case to accommodate the photovoltaic component in the metal case, so that the concentrator photovoltaic unit is formed as one unit. An INDEPENDENT CLAIM is included for concentrator photovoltaic apparatus.    DESCRIPTION OF DRAWING(S) - The drawing is a perspective view of concentrator photovoltaic unit.    Concentrator photovoltaic unit (1)    Resin lens (2)    Photovoltaic component (4)    Holding component (5)    Metal case (6)