# PV Tracking Design Methodology Based on an Orientation Efficiency Chart
## 3 Results  
The energy measurement was performed by recording the power delivered by the fixed PV module and the tracking PV module, i.e., model ERDM250. The voltage and current measurements were performed using an electric circuit with a resistance of 7.5 Ohms and a load of 200 W, as shown in Figure 12. The weather conditions were recorded using an Ambient Weather WS-1001 weather station. The voltmeters are accurate to \(\pm\)0.5%, the ammeter is accurate to \(\pm\)2.5%, and the solar radiation recorded by the weather station is accurate to \(\pm\)15%, according to the manufacturer's specifications [33; 34].  
Figure 11: Solar tracker prototype and components.  
The measured solar irradiation ranged from 0 to 700 W/m\({}^{2}\), and the current values ranged from 0 to 5 amperes based on the PV manufacturer's current-voltage curves (Figure 13). According to the characteristics of the resistance used as the load, the voltage ranged from 0 to 30 volts. These conditions imply that the cells were operating at approximately 50% of their maximum capacity according to the manufacturer's operating curves. Additional important specifications of the PV are as follows: panel dimensions of 1640 \(\times\) 990 \(\times\) 50 mm, maximum power (Pmax) of 250 W, voltage at maximum power (Vmp) of 31 V, current at maximum power (Imp) of 8.08 A, short circuit current (Isc) of 8.8 A, open circuit voltage (Voc) of 37.8 V, polycrystalline type of panel, operating temperature from 40 \({}^{\circ}\)C to 90 \({}^{\circ}\)C, module conversion efficiency (hTref) of 15.39%, power temperature coefficient (bref) of \(-\)0.5%/\({}^{\circ}\)C, and standard testing condition of 1000 W/m\({}^{\ast}\)2 at 25 \({}^{\circ}\)C [35].  
Measurements were taken on a specific date, which was selected based on a study by [PERSON] et al. [36], who found that May, June, and July feature the largest drops in efficiency due to orientation, and other studies [2; 37] that evaluated the performance of a double-axis sun tracking system in comparison to a fixed PV system. The delivered energy measurements were performed using a fixed or tracking PV system of the prototype installed in Cd. Obregon, Mexico (27.5\({}^{\circ}\) latitude and 109\({}^{\circ}\) longitude) and were recorded hourly on July 12, 2018, as shown in Figure 14. These recordings can be considered adequate and congruent measurements, because during the hours around solar noon, the energy production curves of the fixed panel and the tracking panel are similar.  
Figure 12: Schematic of the PV power measurement (tracking and fixed).  
Figure 13: Operating range of model ERDM250 PV [35].  
Figure 15 shows the correlation and variance between the power measurements and incident radiation for the ERDM250 PV. The measurements have a lineal performance with a variance of \(\pm\)10% of the maximum value. These values were determined based on the observations, recording measurements, and responses to electric load.  
The EFO solar-tracking panel collected 24% more energy than the fixed PV panel. This increase in efficiency is expected to be the average value for the range of increments of dual-axis tracking systems that achieve 95-100% EFO. The increased efficiency is similar to the average increased efficiency of 24.5% for the dual-axis solar trackers that use sensors and tracking mechanisms with greater precision [5], as shown in Table 6. The increase in the technician feasibility of dual-axis PV tracking systems for latitudes close to 30\({}^{\circ}\) is similar to that of single-axis solar trackers for latitudes lower than 15\({}^{\circ}\)[38].  
Figure 14: Power and production from fixed and tracking PVs.  
Figure 15: Correlation between power and incident radiation.