###### Abstract
Conversion efficiencies of 23%, 23.1% and 23.3% have also been achieved at the Fraunhofer Institute for Solar Energy Systems (ISE) [13], the Institute for Solar Energy Research Hameln (ISFH) [14] and IMEC [15] at the 2 \(\times\) 2 cm\({}^{2}\) scale. Therefore, in addition to structural improvements, other ways to increase the efficiency of PV-modules should be explored. One of the ways to increase the efficiency of PV-modules is to determine the optimal angle of inclination of the panels to the horizon, and the method of installing the PV-module on the Earth's surface [16]. For example, scientific work [17] is devoted to the study of the average annual installation efficiency of PV-modules with five different tracking options. The average annual installation efficiency of the PV-modules on an arbitrary latitude can reach 47.93%, i.e., be equal to the average annual installation efficiency of a module on the equator with the angle of inclination of the PV-module solar panel to the horizon equal to the value of this latitude. An increase in the average annual installation efficiency of the PV-module up to 50% is achieved with the use of vertical-plane tracking. In turn, tracking in the horizontal plane ensures the achievement of module installation efficiency at the level of 97.93%. However, it is impossible to generalize the obtained results for further use by other authors, since the average annual installation efficiency of the modules is determined only for the options for installing PV-modules on the Earth's surface from the equator to the latitude of 66.55\({}^{\circ}\). Also, the calculated values of the optimal installation angles of PV-modules, the values of which are equal to the values of the geographical latitude of the place of their installation, show deviations from their real values. The justification for this difference is given in scientific works [18]. The authors proposed a methodology for calculating the annual installation efficiency of PV-modules at different geographical latitudes, depending on the adjusted value of the angle of their installation to the horizon. It has been proven that the deviation of the PV-module's installation angle to the horizon from the value of geographical latitude increases with the increase in the numerical value of geographical latitude. In the work [19], the results given in the scientific work [18] were experimentally confirmed. The authors, based on the conditions of monthly and average annual insolation of solar radiation, determined the values of optimal inclination angles of PV-module solar panels for four cases in different climatic zones of Senegal. In all cases, the maximum installation efficiency of PV-module electricity generation occurred at smaller values of the installation angle of the module panels to the horizon, and the values of the geographical latitude were less important. The results of large-scale research on determining the values of optimal angles of inclination of PV-module solar panels are presented in a scientific work [20]. The work was carried out in ninety different capitals of countries located in both hemispheres of the Earth, during the winter and summer seasons. The values of the optimal angles were in the ranges of 41\({}^{\circ}\) to 105\({}^{\circ}\) and 11\({}^{\circ}\) to 90\({}^{\circ}\) for the winter and summer seasons, respectively. The authors proposed a method for determining the optimal angle of inclination of the PV-module solar panels at any point on the Earth's surface, at a given value of geographical latitude, and at the coordinates of the desired location of the PV-module's installation. The results of the analytical calculations are confirmed by numerous experimental data, and they show that the maximum production of electricity by PV-module panels occurs when the angle of inclination of the PV-module panels to the horizon is slightly less than the value of the geographical latitude, which is indicated in works [18; 19].