## 2 Materials and Methods
The authors highlight several advantages of an \"East-West\" PV-modules orientation, such as the reduced costs associated with substation interconnection (especially when PV-modules are slanted at high tilt angles) and the reduced costs for steel structure and mounting piles. A notable disadvantage of the \"East-West\" configuration is its comparatively lower energy yield compared to the \"South\"-orientated modules. The authors conclude that in scenarios requiring significant power input, \"South\"-orientated PV-modules are preferable. Conversely, an \"East-West\"-oriented PV-module with a direct grid connection can provide a smoother power input to the grid with fewer harmonics and less reactive power. The efficiency of the PV-modules described in [46] was assessed using key indicators such as energy production, capacity factor and annual income. The results of the numerical modeling carried out using the Sunny Design software (SMA Solar Technology AG) are confirmed by experimental data obtained in three cities--Nicosia (Cyprus), Maiduguri (Nigeria) and Stuttgart (Germany)--selected for their position relative to the equator. The results indicate that \"East-West\"-oriented PV-modules offer advantages in terms of energy production and capacity factor compared to \"South\"-orientated PV-modules. The distribution of solar radiation over the day improves energy production during peak demand hours. On the contrary, \"South\"-orientated PV-modules show higher annual yields due to their better capturing of solar radiation during certain periods. The study [47] is an excellent example of the practical implementation of what has been described in [38,45,46]. The authors modeled 40 different grid scenarios and compared two variants of PV modules--with \"South\" and \"East-West\" orientations. Two EV charging profiles were also compared for five tilt angles of the \"South\"-orientated PV-modules--from 15\({}^{\circ}\) to 35\({}^{\circ}\)--and two assumptions of potential long-term energy storage (LDES). The conclusion of the study is that while the East-West solar orientation is expected to reduce the need for diurnal storage by allowing EVs to be charged early and late in the day, it appears that a better match between seasonal supply and demand is more important for the south-facing orientation. The present study is characterized by the use of a simplified methodology and results that allow us to complement and explain the studies presented in [38; 45; 46; 47]. The expression (4) of the mathematical model allows for estimating the weighted average cosine of the angle of incidence of the sunlight on the PV-modules. Calculations based on this expression provide a degree of accuracy comparable to commercial software without the need for financial costs. In addition, the application of the mathematical model developed by us is geographically universal, making it suitable for use in different latitudes with appropriate climatic conditions. In contrast to the approaches presented in [38; 46], where the authors study \"East-West\"-oriented PV-modules and then compare them with \"South\"-oriented PV-modules, our study proposes to combine \"East-West\"- and \"South\"-oriented PV-modules into a single system. This is a rational option for consumers with morning and evening peak loads. The experimental results presented in studies [38; 45; 46; 47] confirm the performance of the model developed by us, which will allow it to be widely used to estimate the amount of solar energy received by PV-modules during the day, without significant capital investment in experimental research and the purchase of appropriate expensive equipment. The peculiarity of the conducted research (Figure 7) relates to the establishment of the following facts. The first is that the weighted average daily installation efficiency of the vertical stationary PV-modules with an \"East-West\" orientation is the same as that of vertical stationary PV-modules with \"South\" orientation.