## 6 Results and Discussion
### Impact of SPCR Operation on Landscape PV Module  
The results above indicate that the vibration degradation varies depending on the placement of the SPCR. To further investigate, the SPCR was planned to pass over the PV module along the center (Figure 19a) and the upper side of the PV panels (Figure 19b). The dial gauge (DG) was positioned to measure the deflection of the middle PV panel, capturing vibrations before the SPCR entered and after leaving the PV panel. Figure 20 illustrates the deformation of the PV panel under the passage of the SPCR with/without the installation of the multi-suspension unit along the center and upper side of the PV panels. As the SPCR passed over the center of the PV panels, it induced peak deflections of 18.16 mm and 17.86 mm, respectively, for the SPCR equipped with and  
Figure 19: Investigation of vibration caused by SPCR operation on landscape PV module: **(a)** SPCR passes over the module along the center of the PV panels; **(b)** SPCR passes over the module along the side of PV panels. Figure 18: Variation of deflection deviation with SPCR stopped, yet brushes rotating on different positions of PV panel: **(a)** at the center of the PV panel; **(b)** at the short edge of the PV panel; **(c)** at the long edge of the PV panel. without the multi-suspension unit. Similarly, when the SPCR passed over the PV panels along their sides, peak deflections of 14.58 mm and 14.08 mm were observed, respectively. It is noted that the impact of SPCR operation is considered, so the experimental results encompass the effects of rotating brushes and the PV panel deformation caused by the mass of the SPCR. These findings align with the conclusion that the reduction in vibration is less pronounced when the SPCR is positioned closer to the supporting bar. With the inclusion of the multi-suspension unit, the peak deflection decreased by approximately 1.65% (when located along the center) and 3.43% (along the upper side). Figure 20 indicates that the maximum deflection occurs around 25 seconds when the SPCR traverses over the central PV panel. Both before entering and after leaving the central PV panel, the SPCR still induces deformation and deflection on the panel. Moreover, it is evident that the SPCR, equipped with the multi-suspension unit, significantly dampens the vibration amplitude, resulting in the absence of noticeable vibration spikes. Figure 21 illustrates the variation in \(\Delta z\) values during the 45-s experimental period as the SPCR passes over the landscape PV module. The experiment was conducted both with and without the installation of the multi-suspension unit, considering paths along the center and upper side of the PV panel. Irrespective of the SPCR's trajectory, the results clearly demonstrate a substantial reduction in \(\Delta z\) significant values (exceeding 1.0 mm) when the multi-suspension unit is employed. For instance, as the SPCR moves along the center of PV panels, \(\Delta z\) values larger than 1.0 mm are completely suppressed. At the same time, the \(\Delta z\) value from 0 to 0.5 mm increases from 172 counts to 223 counts. Referring to the results of the stationary SPCR case, the position of the cut-off line, which signifies the level of vibration suppression, is influenced by the vibration amplitude of the PV panel. Given the relatively consistent vibration amplitudes in both experimental scenarios, the cut-off line position remains roughly similar. A noteworthy observation was the symmetric distribution of deflection deviations around zero. This suggests that deflections occur uniformly and cyclically across the PV panel. In these scenarios, the SPCR was planned to pass over the portrait PV module along the center (Figure 22a) and the upper side of the PV panels (Figure 22b). The DG was positioned to measure the deflection of the second PV panel. Figure 23 depicts the deflection of the PV panel with and without the installation of the multi-suspension unit as the SPCR passes over the portrait PV module.