A Hybrid Solar Thermal Collector Design for Residential Use

Various methods have been used to harvest solar energy for residential use. Solar panels have received much attention, but they are relatively expensive and inefficient. Solar thermal collectors are a low-cost alternative, which either use air or water as a medium, but the single medium collector design has limitations in climates with seasons - a practical system using a water medium becomes complicated to keep from freezing during colder months, while a collector using an air medium is useless during hotter months. In this research project, a hybrid solar thermal collector was designed that can function effectively year-round by switching between or mixing these two mediums (i.e. water in warmer temperatures and air in colder temperatures). The captured thermal energy can be utilized directly on-site for residential space heating and/or water heating. An experiment was conducted on the hybrid to determine the characteristics of the two mediums, particularly if there was a significant difference in energy collection efficiency between the two. Two identical hybrid collectors were built and experiments were conducted side by side using air and water mediums respectively. Power generated by each solar collector, in both colder and warmer environments, was calculated using collected temperature data. Using two Student’s t-tests, it was determined that water was more effective than air, especially under warmer conditions. Experimental results showed that the advantage of water over air decreases quickly as environment temperature falls. The result favors the initial hybrid proposal to use water in warmer temperatures and air in colder temperatures.