## 3 Results and Discussion
The LCPV/T-PCM recorded the lowest average temperature due to the shading from the reflectors at the early and late hours of each day, and this can be noticed at 9:30 for all days in Figure 6. Generally, the average temperatures of the four PV panels over the investigated 5-day period for the PV1, PV2, PV3, and PV4 panels were 45.56, 46.29, 42.31, and 39.45 \({}^{\circ}\)C, respectively. The maximum electrical power value that was recorded over the investigated 5-day period for all the PV panels is reported in Figure 7. It can be noticed that the highest electrical power was extracted from the LCPV/T- PCM system (PV4) compared to other systems, and this was only for about 2 h around noon. During these time periods, the PV4 panel produced electrical power that was, on average, 6.30% and 11.06% higher than the counterparts produced by the reference PV panel on Day 1 and Day 2, respectively. This was a direct result of using solar low-concentration system along with the combined effective cooling for the PV4 panel, and that was more pronounced on Day 5. However, in the hours outside noon times, the performance of the PV4 panel dropped dramatically due to the shading from the solar reflectors and the high dissipation of the reflected irradiance over the cells of the PV4 panel. Figure 6: The average temperatures of the four PV panels measured at the back of the cells for 5 days in October 2022. [PERSON] et al. [22] highlighted the importance of coupling the active cooling system when a LCPV system is applied and that can increase the power by 31% if the cell temperature is kept at 25 \({}^{\circ}\)C at high solar irradiance. In the present study, the average ambient temperature over the five days was 32.66 \({}^{\circ}\)C, while, in the summer season of Riyadh, the ambient temperature reaches 46 \({}^{\circ}\)C for several days with also a higher ambient temperature over the night. Therefore, the PCM melting point should be slightly higher than the expected ambient temperature over the year to perform its function in the daylight and solidify over the night. This higher temperature level prevents the PV panel in the PV-PCM system in Riyadh to work close to the standard condition of 25 \({}^{\circ}\)C and receive the ultimate benefits of using a solar low-concentration PV panel. The PV/T-PCM system (PV3) showed better performance over the investigated period compared to the PV1 and PV2 systems. The average daily electrical power of the PV3 panel increased by 4.26, 4.22, 5.03, 4.50, and 3.92 % compared to the PV1 electrical power for Days 1 to 5, respectively. Despite the noticeable decrease in the temperature of the PV3  
Figure 7: The maximum electrical power recorded by the PV analyzer over five days in October for the four PV panels. panel in comparison to that of the PV1 panel, the nonuniform temperature distribution over the relatively large surface area of the cells of the PV3 panel led to power losses. This limited further increase in the performance of the PV3 panel to higher than 5% under the investigated cases. On the other side, the PV2 panel attained a slight increase in the produced power by 0.77, 0.16, 0.61, 0.37, and 0.23% over the corresponding power produced from the reference PV panel during Days 1 to 5, respectively. The PCM used in the PV2 panel needed much more time to release the gained heat to the surrounding air in the afternoon, compared to the case of the PV1 panel. This demolished the positive effect of using the PCM when the comparison extended over an average of 7 h in the daylight under the given investigation. The average daily electrical efficiency of the PV3 panel was recorded as the best one among the PV panels during the five days of investigation, with a maximum increase of about 5.03% on Day 3 over the efficiency of the reference PV panel. This efficiency for the PV2 panel had a negligible increase over the PV1 panel, while it declined considerably for the PV4 panel based on the average over the day, as shown in Figure 8a, where it was in the range of 8.1 to 9.17%.