## 4 Results and Discussion
### Comparison of Various PV Tracking Techniques on the Technical Aspect
As illustrated in Figure 15c, it can obviously be seen that the system is more reliable on the grid for DAT and HSAT, respectively. There is a small difference, the reason for which is the low contribution of renewable energy to the system as previously discussed in Figure 11a, that is risen LCOE. Whereas, the designed system sold more energy than purchased for the VSAT and FTSP, respectively. With significant difference noticed, the main reason is that these two designs contributed more in terms of renewable energy production that led to a decline LCOE. The discussion above showed that vertical single axis tracker(VSAT) has superior economic feasibility for the proposed grid-connected hybrid energy system (PV-FC) based on meteorological data and geographical properties of the specific location. Operation Status of the Optimal Grid-Connected Hybrid Energy System (PV-FC) with the Best PV Tracking Technique  
This section discusses the detailed operation status of the optimal design grid-connected hybrid energy system (PV-FC) for selected vertical single axis tracker(VSAT), which has been considered  
Figure 11:0 (**a**) Net present cost (NPC) and levelized cost of energy (LCOE) for different PV tracking techniques, (**b**) the difference of LCOE of various PV tracker related to vertical single-axis tracker (VSAT) as base case, (**c**) Net energy purchases and energy charge for different PV tracker. as the best PV tracker regarding the techno-economic properties of the system. The optimal size is found at 931 kW PV power, 300 kW electrolyzer power, 100 kg hydrogen tank capacity, 100 kW FC power, 150 kW grid power, and 363 kW inverter power. The PV, FC, and grid are supplemented with each other and provide sufficient power to the load with 0.0281% unmet electric load, 0.0986% shortage capacity. The hourly data of PV power generation, electrolyzer input power, FC power, grid power, and load served power are presented in Figure 16 for seven random days of June. The figure shows that, the PV, FC, and grid power can meet the demand of the load. Furthermore, PV generates more than the demand of load, inputs extra power into electrolyzer for hydrogen production, and possibly sells back to the grid when it is more than the needs of hydrogen production. Additionally, it can be seen that FC operates for a short period to face critical demand at which the load power was more than grid power. The energy generated by the PV section was 2078.265 MWh/year, which accounted for 87.1% of total energy generation. Grid produced 258.016 MWh/year, presented 10.8% of total energy generation, and FC generated 50.066 MWh/year with 2.1% of total generation. The monthly energy generation from the PV, FC, and grid is illustrated in Figure 11:1 The figure shows that the major contribution of production comes from the PV system, where the lowest energy produced was recorded in January/December, which was approximately 140 MWh and maximum in June, which was around 200 MWh. The FC operated in the summer season from April-September, due to the load power was high in summer and over grid capacity. Therefore, FC based back up power generation operates to assist the grid to meet critical demand. Figure 11:2 PV power, electrolyzer input power, FC power, grid purchased, and load power at seven days of June using VSAT. The PV-based power generation is operated 4378 h per year during daylight with longer in the summer than winter and peak power output appeared around noon, as can be noticed from Figure 11:3 The electrolyzer operated 1992 h per year longer during the daylight in summer than in winter, where the PV produced peak output power, as shown in Figure 11:4 The FC behaves as backup power generation, it operates 535 h per year during early night in summer season to face emergency demand power, where the grid could not provide. As illustrated in Figure 11:5  
Figure 11:6 Daily data through the year of electrolyzer input power used VSAT. Figure 11:7 Monthly energy generation of PV, FC, and grid used VSAT.