In the present work, the performance of a stratified and well-mixed solar hot water system was examined under the Hungarian climatic conditions. The system consists of a solar flat plate collector with an effective area of four square metres coupled with a storage tank with a capacity of two hundred litres. An oriented simulation programme was developed for the system components. The heat flow inside the stratified tank was considered to be one dimensional and the temperatures were determined applying simple Euler integration. These temperatures were compared with the well-mixed one. The final results showed that the thermal stratification improved the performance of the system by 12% compared with the well-mixed case. As a result, higher values for the load temperatures were satisfied in day time in the case of stratified tank i.e. increased by about 8°C at noon compared with the well-mixed case.