The aim of this diploma thesis is to demonstrate the influence of pollution on solar thermal collector’s performance. It consists of four chapters describing the theoretical and practical knowledge of this subject. The introductory part deals with a description of the solar energy, the different types of sun radiation flatling the Earth's surface, as well as the ways of their utilization, together with the theory of solar radiation geometry. The issue of refraction and reflection of light is discussed in the next section. An analysis of the current status of solar collectors, their overview, the distribution and the description of the various parts follows. The types and forms of pollution which are described and connected with experimental measurements in the fourth chapter, confirming the negative influence of pollution on the performance of these equipments. At the end, there is a summary of the knowledge about the pollution of solar collectors.