NOVELTY - The collector has a heat collector (29) i.e. stainless steel tube, rigidly supported above a reflective surface of a parabolic reflector by a supporting arm (47). The parabolic reflector comprises an outer metallic sheet coated with a reflective layer on an outer surface. The outer metallic sheet, another outer metallic sheet and an inner layer are assembled together in a unitary parabolic shape and reinforced with longitudinal rails (27, 28) and lateral rails. The supporting arm is connected to the heat collector and to the parabolic reflector, and the inner layer is made of polymer.    USE - Rigid self-supporting solar collector for a solar concentrator (claimed) for power generation or steam generation in a residential building, a commercial building and an industrial sector such as food processing sector, paper pulp processing sector, hospitality sector and health sector.    ADVANTAGE - The collector has simple structure such that the collector can be assembled easily and rapidly, transported easily, and manufactured at low cost. The collector minimizes shadows on solar collection surfaces, thus optimizing performance of sun concentration. The design of the collector ensures that a solar concentrator unit is simple, modular, scalable and robust and can be used in adverse environments such as arid or Nordic climates. The heat collector is designed such that vacuum is achieved between inner and outer tubes of the heat collector to minimize thermal loss while letting sun beams to pass through.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a solar concentrator    (2) a self-supporting reflector    (3) a heat collector    (4) a joint for tubular units of a solar tubular collector    (5) a system for recovering solar energy by solar energy concentration.    DESCRIPTION OF DRAWING(S) - The drawing shows a side perspective view of a solar concentrator unit.    Solar concentrator (10)    Parabolic mirrors (22, 23)    Longitudinal rails (27, 28)    Heat collector (29)    Supporting arm (47)