Investigating the performance of a solar collector with plastic bottles as a glazing cover

Conventional flat plate collectors have found widespread use in both domestic and industrial applications. Despite the high potential for solar collectors in areas with enormous solar energy resource, one major factor limiting its uptake, most especially in low-income communities of sub-Saharan Africa, is its high initial cost. The replacement of flat glazing cover with transparent Polyethylene Terephthalate (PET) plastic bottles has been identified as one way of minimising cost. PET bottles constitute a significant percentage of the waste stream and can be upcycled at no cost. This also contributes to reducing plastic waste in the environment. This study investigates the performance of a solar collector design with plastic bottles as glazing cover. The collector system simply consists of a serpentine arrangement of copper tubes inserted in PET bottles enclosed in an insulated casing. Aluminium foil sheet was used as diffuse reflector in order to maximise solar radiation captured by the absorber pipes. Experimental investigation of the system was carried out under ambient weather conditions in Zaria, Nigeria; Solar Irradiation ranged from 750 to 950 W/m2, ambient temperatures ranged from 20 to 32 °C and wind speed was in the range 0.5 to 3 m/s. The measurements were used to estimate the standard parameters for predicting and evaluating the performance of flat plate collectors such as the instantaneous efficiency. This analysis, which indicated promising performance results, is important for optimising design and operating parameters for this low-cost design of solar water heater.