In order to contribute to widespread use of RES in Turkey, a solar-assisted ground source heat pump system was modeled using TRNSYS software and simulated for heating and supplying daily hot water to meet the needs of a restaurant in five sample provinces having different climatic conditions. During the simulation, the dining room temperature of the restaurant was kept constant at 22 degrees C during the winter season and a total of 300 Lph of water (55 degrees C) was used for 15 minutes four times a day. According to the simulation results, power consumption rates in the solar-assisted ground source heat pump system were determined as about 60% for the heat pump, 16% for heaters, 14% for the ground pump and 8% for fans and other pumps. The highest power consumption, as expected, was obtained for Hakkari Province (6723 kW) in the Eastern Anatolia region, which has a cold climate, while the lowest power consumption was obtained for Izmir Province (2822 kW) in the Aegean region, which has mild climatic conditions. The lowest seasonal performance factor and solar factor values were calculated as 2.27 and 32% for Hakkari and the highest as 2.71 and 56% for Izmir; respectively.