Although the approach for developing polymeric collectors is rather an approach from the material side, some requirements for the use in domestic hot water heating and possibly heating support should be met regardless of the used material. It is very important, that temperatures of up to 90 — 100°C are tolerated. In addition, UV-stability is essential as well as chemical resistance to the heat transfer fluid. Other properties that are important in the end are e. g. the absorption, heat conductivity, mechanical stability and processability.

Some appropriate polymers and a selection of important properties are presented in table 1. They have been used for the different calculations and might be candidate materials for solar thermal applications. The values used are a compilation from various sources.

Most thermoplastics — including the ones mentioned in the table — are extrudable, so the advantages of this well-known, effective continuous process can be used. However, it seems to be impossible to find one polymer that fulfils all the aforementioned needs as it is. Thus, one has to look for possibilities to modify polymers in order to serve one’s purposes. Additives and fillers might be used to increase the heat conductivity, as well as the heat stability and they can be used as a protection against UV-radiation if no special UV-screen on top of the polymer is used.