## 2 Materials and Methods
Such an algorithm made it possible to set the angle of inclination of the stationary PV-modules to the horizon, and to determine the installation efficiency of such an installation. Simulation modeling and the generalization of the results were carried out in the Microsoft Excel environment. The Installation Efficiency of Vertical Stationary PV-Modules Equipped with a Double-Sided Solar Panel with an \"East-West\" Orientation  
The Determination of Characteristic Angles of Incidence of Rays on Double-Sided Solar Panels of Vertical Stationary PV-Modules  
The calculation of the characteristic angles of incidence of the rays for vertical stationary PV-modules equipped with a double-sided solar panel with \"East-West\" orientation at a latitude of 50\({}^{\circ}\) is shown in Table 1. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Moment of Time** & **Sunrise** & **At Noon** & **Sunset** \\ \hline \multicolumn{4}{c}{Angular length of a day at latitude of 50\({}^{\circ}\)} \\ March 21 & 0.00 & 89.63 & 179.25 \\ June 21 & 0.00 & 121.13 & 242.26 \\ December 21 & 0.00 & 58.87 & 117.74 \\ \multicolumn{4}{c}{Horizontal azimuth of the Sun (axis y), \(\theta_{H}\)} \\ March 21 & 90 & \(-\)0.31 & 90 \\ June 21 & 90 & 23.45 & 90 \\ December 21 & 90 & \(-\)23.45 & 90 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristic angles of incidence of the rays for vertical stationary PV-modules equipped with a double-sided solar panel with “East–West” orientation. The change in the horizontal and vertical azimuths of the Sun's rays' incidence on a double-sided solar panel of a vertical stationary PV-module during the day is given in Figures 2 and 3. \begin{table}
\begin{tabular}{c c c c} \hline
**Moment of Time** & **Sunrise** & **At Noon** & **Sunset** \\ \hline \multicolumn{4}{c}{Cosine of the Sun’s horizontal azimuth, cos\(\theta_{H}\)} \\ March 21 & 0.000 & 0.99998 & 0.000 \\ June 21 & 0.000 & 0.917 & 0.000 \\ December 21 & 0.000 & 0.917 & 0.000 \\ \multicolumn{4}{c}{The cosine square of the Sun’s horizontal azimuth, cos\({}^{2}\theta_{H}\)} \\ March 21 & 0.000 & 0.99997 & 0.000 \\ June 21 & 0.000 & 0.842 & 0.000 \\ December 21 & 0.000 & 0.842 & 0.000 \\ \multicolumn{4}{c}{Vertical azimuth of the Sun (axis \(x\)), \(\theta_{V}\)} \\ March 21 & 89.69 & 89.69 & 89.69 \\ June 21 & 113.45 & 113.45 & 113.45 \\ December 21 & 66.55 & 66.55 & 66.55 \\ \multicolumn{4}{c}{Cosine of the Sun’s vertical azimuth, cos\(\theta_{V}\)} \\ March 21 & 0.00549 & 0.005 & 0.00549 \\ June 21 & \(-\)0.398 & \(-\)0.398 & \(-\)0.398 \\ December 21 & 0.398 & 0.398 & 0.398 \\ \multicolumn{4}{c}{The cosine square of the Sun’s vertical azimuth, cos\({}^{2}\theta_{V}\)} \\ March 21 & 0.00003 & 0.00003 & 0.00003 \\ June 21 & 0.158 & 0.158 & 0.158 \\ December 21 & 0.158 & 0.158 & 0.158 \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 2: The change in the horizontal azimuth of the Sun’s rays incidence on a double-sided solar panel with an “East–West” orientation on a vertical stationary PV-module during a day. The change in the cosine of the horizontal and vertical azimuths of the Sun's rays falling on a double solar panel with an \"East-West\" orientation of vertical stationary PV-modules during the day is shown in Figures 4 and 5. Figure 4: The change in the cosine of horizontal Sun rays falling on a double-sided solar panel with an “East–West” orientation on a vertical stationary PV-module during a day. Figure 3: The change in the vertical azimuth of the Sun’s rays’ incidence on a double-sided solar panel with an “East–West” orientation on a vertical stationary PV-module during a day. The above calculations allow us to determine the cosine of the angle of incidence of the rays on the double-sided solar panel of the PV-module and the installation efficiency of the vertical stationary PV-module at a latitude of 50\({}^{\circ}\).