## 5 Experimental Data Analysis of the Isolated PVPS (Acquisition and Log)
The day characterized by multiple small and rapid clouds generated approximately 409 kWh with a peak of 49.42 kW (Figure 7c) and the fully cloudy day had the lowest energy production of about 175.14 kWh, despite reaching a peak of 51.18 kW (Figure 7d). Figure 8 shows voltage variations on the isolated PV generator DC bus and the VFD DC bus (link) (left \(y\)-axis) along with their differences, defined as electrical shocks, occurring exclusively during PVPS operation (right \(y\)-axis), for the four representative days. The analysis presented here focuses solely on identifying and quantifying these electrical shocks  
Figure 7: Isolated PV generator produced power [kw] during the 4 representative days: (**a**) clear-sky day, (**b**) day with a big cloud, (**c**) day with many small clouds and (**d**) fully cloudy day. as indicators of system performance; assessing their potential impact on the lifespan of equipment is beyond the scope of this study and reserved for future research. Analyzing Figure 8, the number and amplitude of electrical shocks varied significantly across the four representative days. On the clear-sky day, shocks were fewest and of the smallest magnitude (<45 V), appearing briefly only during sunrise and sunset, and therefore were negligible. During the day partially obscured by a large and dense cloud, shocks remained relatively infrequent and had a low amplitude (<55 V), indicating that the PVPS effectively managed gradual irradiance fluctuations. However, the highest frequency and amplitude of shocks occurred on the day characterized by multiple small, rapid clouds, including two notable electrical shocks exceeding 200 V. On the fully cloudy day, the limited PV generator output resulted in short operational intervals; therefore, fewer shocks occurred, with one event around 140 V and the remaining below 80 V.  
Figure 9 compares the measured and theoretical (design-based) pump motor power consumption (in kW), where the theoretical values represent steady-state operation under rated flow and pressure conditions. Analysis of Figure 9a reveals two unsuccessful initial start attempts on the clear-sky day, caused by a mismatch between the real and estimated available PV generator power, where the actual available power initially remained below the minimum threshold needed for the cooling flow of the pump motor. Apart from sunrise and sunset periods, when the absorbed power directly tracked the declining PV output, the measured and theoretical values closely aligned throughout the day. On the day partially obstructed by a large, slow-moving cloud (Figure 9b), the measured and theoretical power aligned closely during the rated operation; however, the real system started approximately 30 min later due to a higher practical power threshold required for startup. Additionally, the real system employs a conservative, real-time safety control strategy based on a timer and counter designed to limit repetitive start attempts, thereby protecting system components. Specifically, after two consecutive unsuccessful start attempts, the system initiates a 10 min delay before retrying. If the subsequent attempt  
Figure 8: Voltage variation [V] and its first derivative of the isolated PV generator DC bus during the 4 representative days: (**a**) clear-sky day, (**b**) day with a big cloud, (**c**) day with many small clouds and (**d**) fully cloudy day. after this delay also fails, the system imposes an additional 20 min delay while simultaneously resetting the attempt counter. Consequently, this mechanism restricts the maximum number of startup attempts to six per hour (e.g., two attempts at minute 0, one at minute 10, two at minute 30, one at minute 40 and again two at minute 60). Similar behavior was observed on the day with multiple small, fast-moving clouds (Figure 9c), confirming the necessity of this safety measure.