Thermal Performance Assessment of a Flat-Plate Solar Collector for Water Heating in Ibadan, Oyo State

Growing energy costs and unreliable electricity supply across South West Nigeria have renewed interest in solar thermal systems as a practical means of meeting domestic hot water needs. This study assesses the thermal performance of a locally constructed flat-plate solar water heating collector tested under the climatic conditions of Ibadan, Oyo State. The collector was fabricated using a blackened copper absorber plate, a glass cover, fibre insulation, and a galvanised steel casing, with all components sourced from local suppliers. A thermosiphon circulation system connected the collector to a 100-litre insulated storage tank. Thermal performance tests were conducted over 20 operational days spanning the dry and transitional seasons, with measurements of inlet and outlet water temperatures, ambient temperature, and solar irradiance recorded at 30-minute intervals. Daily collector efficiency, useful heat gain, and stagnation temperature were computed from recorded data. The collector achieved average daily efficiencies ranging from 42 to 58 percent, with peak useful heat gains of 2.4 MJ recorded during high irradiance periods. Water temperatures in the storage tank consistently reached between 55 and 68 degrees Celsius by mid-afternoon, sufficient for domestic bathing and washing needs. Cost analysis showed that the system could recover its fabrication cost of 65,000 naira within approximately 18 months through fuel and electricity savings. Keywords: flat-plate solar collector, thermal performance, water heating, solar energy, Ibadan.