## 4 Discussion and Conclusions  
The simulation results obtained are the basis for the construction of effective control algorithms of dual-axis tracking systems. Research has shown that much higher positioning accuracy is required for CPV-type modules than for standard silicon modules. Control algorithms for these types of PV modules require frequent checks on the position of the Sun's apparent movement in the sky. For the module under consideration, a deviation of the incidence angle from perpendicular above 5\({}^{\circ}\) causes a drastic decrease in the module power (by about 92%). The results showed less sensitivity to the deviation of the radiation direction than in some other studies [13]. The detailed adaptation of the proposed model of multilayer concentric PV cells requires very precise knowledge of the geometry of the focusing radiation element. Unfortunately, the data sheets of this type of PV modules do not always provide these technical details and the task is then made difficult as in the case considered in this work.  
Figure 10: Simulation results for irradiance of 300 W/m\({}^{2}\) deflected by an angle \(\Delta\theta=10^{\circ}\) from the direction of perpendicular incidence and a temperature of 21 \({}^{\circ}\)C for the modeled CX-75/200 module: (a) current–voltage characteristics I = f(U); (b) power graph P = f(U).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Deviation of the** & **Short-Circuit** & **Open-Circuit** & **Maximum Power** \\
**Radiation Angle** & **Current** & **Voltage** & **Point** \\
**\(\Delta\theta\), (deg)** & **\(I_{\text{SC}}\), (A)** & **\(U_{\text{OC}}\), (V)** & **\(P_{\text{MPP}}\), (W)** \\ \hline
0 & 0.2047 & 129.424 & 26.4931 \\
2 & 0.2046 & 129.76 & 26.5489 \\
4 & 0.2042 & 129.5803 & 26.4603 \\
5 & 0.052 & 117.2519 & 6.0971 \\
10 & 0.051 & 120.3843 & 6.1396 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Numerical results of current–voltage characteristics and power values for each deflection angle used in this simulation for a fixed irradiance of 300 W/m\({}^{2}\) and an assumed module temperature of 21 \({}^{\circ}\)C.  
The studies, which attempted to solve this problem in an analytical way [27], led to positive verification of the adopted models. The problem that should be addressed in the future is the issue of economic viability of this type of solutions. Comparative analyses for evaluating the impact of the radiation spectrum on the energy yield of highly concentrated and conventional photovoltaic technology are based on the air mass (AM) factor in many studies [28].  
The model proposed in this paper can be easily modified for other non-standard solutions, such as cells with more layers of semiconductor material. It is also possible to modify the module that calculates the geometric parameters of the direct solar radiation direction. The proposed model can also be modified to use other solar beam focusing mechanisms. The photovoltaic market in Central Europe, based on the example of Poland [29], has to be more and more competitive and look for more and more efficient technical solutions. The model proposed in this paper can also be adapted in the future to the latest solutions, consisting in combining classical silicon with new materials such as perovskites. Another new challenge for modeling such systems will be to predict the durability of such cells. For classical silicon PV modules, an average annual power loss of about 0.8% is currently assumed [30].  
This paper demonstrates that different PV cell structures operate on similar solar radiation conversion mechanisms. After appropriate adaptation, proven and tested engineering software components such as \"Solar Cell\" of the Matlab/Simulink package can be used to conduct simulation experiments of cells with various unusual structures. In classical applications in earlier work [31; 32; 33], the author has positively verified the usefulness of the \"Solar Cell\" component of the Matlab/Simulink engineering computing package.  
This research received no external funding.