A support system for a trough-shaped solar collector assembly includes a support arm comprising first and second curved rails and an interconnecting web structure. The web structure is secured along first and second opposite edges thereof to first and second web engaging structures, which are provided along facing surfaces of the first and second rails, respectively. Prior to fixedly securing the web structure to the web engaging structure of the first and second curved rails, the location and/or the orientation of the web structure are adjustable for supporting interconnection of the first and second curved rails with different rates of convergence between the first and second curved rails. The support arm further includes a plurality of mirror-attachment brackets coupled to the first rail for attaching the trough-shaped solar collector assembly to the support arm and structure attachment brackets for mounting the support arm to a structure.