## 5 Discussion  
An on-off control algorithm is used in approximately 57% of the STSs reported in the literature because of its ease and low-cost implementation [12]. This algorithm, however, has several disadvantages such as low tracking precision, low attenuation of the effect of disturbances, as well as requiring a large tracking hysteresis to avoid instability that could cause excessive electrical consumption and wear in the actuators. Because of the characteristics of the slew drive used in the developed STS, the on-off control showed a good performance, achieving high precision solar tracking with robustness against climatic disturbances.  
Section 4.4 detailed the construction cost of the proposed STS, which is higher than most of the STS reported in the literature. This cannot, however, be objectively compared with the cost of prototypes of solar trackers since the presented system reached a TRL 7-8. In other words, it has been validated in relevant environments, is low maintenance, can work outdoors, among other advantages. In addition, the axial and radial load capacity of the developed STS is much higher than that presented in prototypes. The cost analysis was performed to estimate the return on investment of the STS if a conventional PV system is considered as the payload. The developed STS, however, is focused on CPV modules, which require greater precision and accuracy of solar tracking. In such systems, small deviations can considerably reduce the performance of the modules, as analyzed in Section 4.3; therefore, a high precision tracking system is vitally important.  
On the other hand, Table 1 shows that high precision and low-cost solar trackers have been reported in various works. Typically, however, the characterization of their precision was not performed using a standardized methodology, or only the error measured in the  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Pieces** & **Element** & **Cost (USD)** \\ \hline
1 & PDE3 slew drive & §976 \\ \hline
4 & Industrial limit switch & §55 \\ \hline
1 & Connection accessories & §30 \\ \hline
1 & Steel pole structure and frame & §1115 \\ \hline
4 & Aluminum profiles & §50 \\ \hline
1 & Concrete isolated footing & §350 \\ \hline
1 & ISS-A60 analog solar sensor & §170 \\ \hline  & Total & §2746 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Approximate cost of the solar tracker.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Pieces** & **Element** & **Cost (USD)** \\ \hline
1 & Arduino Mega 2560 & §50 \\ \hline
2 & BTS7960 H-bridges & §11 \\ \hline
1 & Nextion touch screen NX8048T070 & §75 \\ \hline
1 & Basic electronic elements & §30 \\ \hline
1 & Four-channel 5 V relay module & §50 \\ \hline
1 & Control panel and connection accessories & §210 \\ \hline
1 & 24 VDC and 5 VDC power supplies & §33 \\ \hline  & Total & §459 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Approximate cost of the control and monitoring system.  
control system is reported, which does not consider the errors caused by other factors [12]. On the contrary, the developed STS achieved an average solar tracking precision of 0.390\({}^{\circ}\) on clear sky days, which was measured using a procedure adapted from the IEC 62817 standard, so the reliability is relatively high.