The analysis of thermal performance of the flat-plate collector includes parameters such as solar intensity, ambient temperature and configuration of flat-plate collectors etc. In this research work, the effect of the parameters on thermal performance of glazed flat-plate solar collector was analyzed for water heating application in winter climatic condition. The flat-plate collector consists of the total surface area 2.23 square meter and the copper tubes are integrated beneath the absorber plate. The plate has a selective coating with high absorptivity of 92% and the heat transfer fluid flowing in the tubes is R-134a. In the work, evaluation of useful heat gain or collector efficiency has been done. It is based on steady state analysis and by calculating the thermal performance of liquid flat-plate collector. Results show that the flat-plate collector gives good performance and provide a desire quantity of hot water.