The performance of a solar flat-plate thermal collector wholly manufactured in a copolymer material is studied. The influence of different parameters of the system such as the insulation thickness, the flow rate and the fluid layer thickness is analysed. Thermal performance, productivity and efficiency of such a solar system is presented for a Mediterranean site. Yearly mean efficiencies are about 56.5% in no wind and about 49.0% for a wind speed of 5 in s(-1). The use of polymer materials reduces the collector weight by 50% in comparison with a traditional metal collector, this renders easier installation. (C) 2002 Elsevier Science Ltd. All rights reserved.