The features of using the sun energy are described in the introduction of this master's thesis. The sun energy has many advantages, so it should be used increasingly in the future. This thesis describes the main parts of the solar heating system in detail. There is a description of the following parts: solar collectors, pipe distribution, solar warm water collectors, solar circulating pump, safety and regulation equipement, followed by the description of the solar warm water systems, the most important of which are preparation of used warm water system, system with one tank for preparation of used warm water, warm water system with double tank, warm water system with two tanks and systems for heating of rooms and pools. After the theoretic part there is a calculation of the heat load of facilities in Slavonski Brod. The heat load of facilities is important for the calculation of heat energy for annual heating. In the process of dimensioning of solar system it is necessary to take many parameters in order to optimally define the size of the container and the needed number of collectors. After choosing the adequate solar container, calculation of solar collector was made and the adequate collector was chosen. The calculation of pressure drop and solar cycle pump was also made. The needed heat energy for monthly heating and the heat energy produced by solar system, as well as the comparison of it with total needs of the heat season were calculated for the calculation of energy consumption. Through the production of one part of energy with solar system there comes to savings in the overall consumption. The savings in the heat energy that are made through the usage of the solar system during the year are determined by simulation results and they are equal to used sun energy for water heating. In this thesis it comes to 20 % of the total consumption. In the very end there is an overall conclusion of this master's thesis.