In this paper, we present the mathematical modeling of the optimal angles of a solar collector and a solar collector with a sunray concentrator. The quantity of solar energy depends on geographical position, the trajectory of the sun, on the intensity of solar radiation energy, of sunlight duration per day and per year, the reflection coefficient of SRR, etc. Therefore, in different seasons, we will have different optimal angles of a solar collector. In Lithuania, the optimal angle of tilt of a solar collector is determined experimentally is 15° to 60° for the whole year: 15°...45° in winter and 30°... 60° in summer.

The mathematical model presented in this paper gives the possibility to calculate the optimal angles of tilt of a solar collector and a solar collector with a sunray reflector in a selected geographical position, the collector exploitation period, the geometrical parameters of a solar collector and a sunray reflector, etc. A comparison of the mathematical modeling and experimental data are presented and conclusions are made.

Keywords: solar collector, reflector, solar ray reflector, optimal angles, solar radiant energy, mathematical modeling