This work presents numerical simulations aimed at optimizing the design of polymer flat plate solar collectors. Solar collectors' absorbers are usually made of copper or aluminum and, although they offer good performance, they are consequently expensive. In comparison, using polymer can improve solar collectors economic competitiveness. In this paper, we propose a numerical study of a new design for a solar collector to assess the influence of the design parameters (air gap thickness, collector's length) and of the operating conditions (mass flow rate, incident solar radiation, inlet temperature) on efficiency. This work outlines the main trends concerning the leading parameters impacting the polymer flat plate solar collector's efficiency. (C) 2012 Elsevier Ltd. All rights reserved.