## 3 Results  
This section describes the incident radiation values on collectors and the results of the study of the influence of the design variables on the solar incidence on the PV plant designs considered. The synoptic values obtained for the annual incident radiation in collectors are summarized in Table 2. Figure 10 shows the distribution of values obtained depending on the membership intervals. In the set of values obtained, it is observed that certain forms of the collector offer the same value. These are the cases in which the set of cuts A, B, C and D of Figure 11a are permuted as shown in Figure 11b-d,f-i. A detailed analysis of the procedure followed makes it possible to verify that the shape of the solar collector does not influence directly but rather through its envelope. As a consequence, the collector shapes of the first column (11 (a), 11 (b), 11 (c), 11 (d)) give rise to identical annual radiation results since they all give rise to the same envelope \(\Sigma\) (represented in Figure 11e). On the other hand, the coincidence of radiation outcomes in the results between the collector shapes of the first (Figure 11a-d) and the second column (Figure 11f-i) should be understood as a consequence of the symmetry with respect to the NS axis of the studied configurations and of the symmetry with respect to this plane in the positions of the sun between the hours of the morning and afternoon. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Month** & **\(H\) (j/m\({}^{2}\))** & **Representative Day** \\ \hline January & 7,401,000 & 17 \\ \hline February & 11,097,000 & 47 \\ \hline March & 14,158,000 & 75 \\ \hline April & 17,307,000 & 105 \\ \hline May & 19,017,000 & 135 \\ \hline June & 24,263,000 & 162 \\ \hline July & 25,719,000 & 198 \\ \hline August & 23,411,000 & 228 \\ \hline September & 17,983,000 & 258 \\ \hline October & 11,895,000 & 288 \\ \hline November & 8,228,000 & 318 \\ \hline December & 6,237,000 & 344 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Data considered for the estimation of the annual solar irradiance in “El Molino” PV Plant (Cordoba, Spain): horizontal daily radiation, \(H\)[48] and representative day proposed by [47] each month of the year. \begin{table}
\begin{tabular}{c c} \hline \hline
**Number of Cases** & **25,000** \\ \hline Average & 2172.0 \\ \hline Minimum & 2040.2 \\ \hline Maximum & 2233.8 \\ \hline Median & 2189.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Descriptive parameters of the set of values of \(H_{year}\) (kWh/m\({}^{2}\)). Figure 11: Set of collector shapes that generate identical annual incident radiation results. The forms (**a**–**d**) generate the same envelope \(\Sigma\) (**e**) and the set of symmetric figures with respect to a vertical axis (**f**–**i**) generate a symmetric envelope \(\Sigma^{\prime}\) of \(\Sigma\) (**j**). Figure 10: Distribution of annual solar radiation values (\(H\)) according to membership intervals. The dependence of the values obtained with respect to the considered design variables was studied using an approximation and simplified model, in which the calculated annual radiation was expressed as a function of the following explanatory variables:  
* Collector surface \(S_{col}\left(m^{2}\right)\). * Distance between trackers in east-west direction, \(D_{EW}\)\(\left(m\right)\)
* Distance between trackers in north-south direction, \(D_{NS}\)\(\left(m\right)\)
* Discriminatory variable of the type of configuration T (T = 1 for staggered configurations and T = 0 for regular grids). In this sense, it is worth highlighting that the model described and used (for each of the 25,000 cases) can be considered a mathematical function of the variables proposed. However, the complexity of the model and the need to aggregate results on the different representative days made it difficult to know the weight or influence of each variable on the final results.