## 3 Results and Discussion
### \(PV\) Power Plants Under Study  
For the analysis of the influence of the movement limit on the incident solar irradiance on the \(PV\) field, the following three \(PV\) power plants have been selected from Table 1: (i) the Miraflores \(PV\) power plant, (ii) the Basir \(PV\) power plant, and (iii) the Canredondo \(PV\) power plant. The criteria on which this choice is based are as follows:  
1. The selected \(PV\) power plants should have different levels of horizontal global and diffuse solar irradiance, in order to analyse the influence of the \(\beta_{max}\) on the incident solar irradiance on the \(PV\) field. 2. The selected \(PV\) power plants should have a limit of movement equal to \(\pm\)60 (\({}^{\circ}\)), in order to be able to compare the results obtained from other limits of movement. The technical and geographical characteristics of the investigated \(PV\) power plants are presented in Table 2.  
As discussed in Section 2, the meteorological conditions of the \(PV\) power plants under study are a key factor in this type of work. Therefore, the procedure described in Section 2 was used for the calculation of the hourly distribution of incident solar irradiance [29]. The input data were obtained from the \(PVGIS\) database [31]. Table 3 shows the horizontal solar surface irradiations at the \(PV\) power plants obtained with the \(PVGIS\) database [31]. In this study, it was necessary to consider how the meteorological parameters of the site under study affect the choice of the movement limit. For this purpose, the meteorological factor called cloudiness index was considered. The cloudiness index (\(k_{d}\)) takes into account beam and diffuse solar irradiance, thus showing the cloudiness of the sky and/or the turbidity of the atmosphere [33]. The higher the cloudiness of the sky, the higher the \(k_{d}\). The cloudiness index is defined as the ratio of the horizontal diffuse solar irradiance (\(I_{dh}\)) to the horizontal global solar irradiance (\(I_{gh}\)) as follows [10]:  
\[k_{d}=\frac{I_{dh}}{I_{gh}} \tag{15}\] \begin{table}
\begin{tabular}{l l l l} \hline
**Specifications** & **PV Power Plant** & & \\ \hline  & **Basir** & **Miraflores** & **Canredondo** \\ \hline Location & Medina Sidonia, (Spain) & Castuera, (Spain) & Canredondo, (Spain) \\ Latitude & 36\({}^{\circ}\)20\({}^{\prime}\)24\({}^{\prime\prime}\) N & 38\({}^{\circ}\)46\({}^{\prime}\)4.8\({}^{\prime\prime}\) N & 40\({}^{\circ}\)47\({}^{\prime}\)58.886\({}^{\prime\prime}\) N \\ Longitude & 5\({}^{\circ}\)50\({}^{\prime}\)32.6\({}^{\prime\prime}\) W & 5\({}^{\circ}\)32\({}^{\prime}\)49.199\({}^{\prime\prime}\) W & 2\({}^{\circ}\)31\({}^{\prime}\)26.95\({}^{\prime\prime}\) W \\ Altitude (m) & 104 & 389 & 1162 \\ Power (MWp) & 20.013 & 22.000 & 21.980 \\ PV mod. number & 37,408 & 41,122 & 41,084 \\ PV mod. model & LR5-72 HBD 535 (LONGI) & LR5-72 HBD 535 (LONGI) & LR5-72 HBD 535 (LONGI) \\ PV mod. dim. (mm) & 2256 \(\times\) 1133 & 2256 \(\times\) 1133 & 2256 \(\times\) 1133 \\ Tracking type & Horiz. single-axis tracker & Horiz. single-axis tracker & Horiz. single-axis tracker \\ Type of control & Astronomical algorithm & Astronomical algorithm & Astronomical algorithm \\ Rotation angle & \(\beta_{\text{max}}=\pm\)60 (\({}^{\circ}\)) & \(\beta_{\text{max}}=\pm\)60 (\({}^{\circ}\)) & \(\beta_{\text{max}}=\pm\)60 (\({}^{\circ}\)) \\ Configuration & 1V & 1V & 1V \\ Pitch (\(e_{t}\)) (m) & 6000 & 6500 & 5100 \\ Reflectance (\(\rho_{g}\)) & 0.2 & 0.2 & 0.2 \\ \hline \end{tabular}
\end{table} 
Table 2: Specifications of the PV power plants.