The designed solar thermal collector system, composed of three Vitosol 100-F collectors, is used for underfloor heating, preparation of domestic hot water, both in combination with the air to water compressor heat pump CIAT Ereba 12 HT with nominal power of 11,2 kW, as well as outdoor swimming pool reheating. The combined system is located in the town of Rab. The preparation of domestic hot water is realized in the accumulation tank SUNEX FISH S3 600, to which the solar heat collectors and the heat pump are connected by individual pipelines. Redirection of the flow of the heating medium, in regards to the heating or preparation of domestic hot water, is controlled by three-way motor mixing regulation valves based on the signals emitted by temperature sensors. In this system, solar energy has the advantage of usage due to its renewability and cost. Swimming pool reheating is done during the hot summer months when there is no need for heating the house. The system is equipped with two expansion vessels Reflex N 12, one on the heat pump pipeline, and the other on the solar thermal collector pipeline. The return of the investment in the solar collectors and the storage tank will be realized in 13.6 years thanks to the annual savings on electricity consumption for the operation of the thermoelectric system due to the use of free solar energy.