Abstract
Present work involves a theoretical energetic and exegetic analysis on the thermal efficiency of the flat plate solar system under variables water inlet temperature and heat loss coefficient. The experimental analysis has been performed based on experimental data that conducted under outdoor conditions of Duhok city at north of Iraq in May 2019. The operating conditions and solar irradiance on the energetic and exegetic efficiencies of the system have been tested. The results displayed that the climatic conditions have significant effect on the energetic and exegetic performance outputs. The solutions also display that the mass flowrate has a proportional relation with energy and exergy performances. Furthermore, the results show that the water inlet temperature has an inverse relationship energy efficiency and a proportional relationship with exergy efficiency. The energy efficiency has been increased with increasing the solar irradiance, whereas the exergy efficiency has been decreased with rising the solar irradiance. The maximum energetic and exegetic performances have been found equal 70% and 4% respectively.