Use of plastics in solar energy applications

Abstract A discussion of the state-of-the-art on the use of plastic materials in solar energy applications is presented, with particular emphasis on their suitability and durability. The availability of plastics in many types and shapes (including sheeting material, films and foams) accounts for the wide range of current and potential applications in solar energy installations. Consequently, actual and potential uses of plastics include: covers (glazings), honeycomb structures and housings for flat-plate collectors; reflecting surfaces, optical lenses, shells, structural and support members for solar concentrating collectors; and insulation and piping. The plastics that have been discussed in this article in relation to their use as components in solar installations include poly(methyl methacrylate) (PMMA), polycarbonate (PC), glass fiber-reinforced polyester (GRP), poly(vinyl fluoride) (PVF), fluorinated ethylene-propylene (FEP) copolymer, poly(ethylene terephthalate) (PET) and various foamed plastics. The aging behaviour of most of these plastics has been widely studied for normal outdoor exposure and in artificial weathering devices, and are thus briefly described here. Very little information is available, however, regarding their short-term performance under actual service conditions in solar energy installations; none has been reported on their long-term durability. Plastics have various degrees of flammability and therefore special care should be taken by using materials with adequate fire resistance and/or appropriate design in applications where a fire hazard may exist.