## 6 Optimization and Simulation Results
### Energy Yield Analysis  
Figure 13 summarises the annual energy contributions of different sources for different average daily solar radiation values at a wind speed of 4.0 m/s. The energy delivered to the SPV array load depends on the value of solar radiation and the size of the SPV array. However, the energy delivered to the load of the WTG is the same because the optimal WTG size is fixed. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **Resources** & & **Optimum Sizing** & & & **Costs Factor** & \\ \hline
**Wind Speed** & **Radiation** & **SPV** & **WTG** & **Battery** & **Inverter** & **Initial Cost** & **Annual** & \\
**(m/s)** & **(kWh/m\({}^{2}\)/day)** & **(kWh)** & **(kW)** & **(unit)** & **(kW)** & **(IC) S** & **O\&M (S)** & \\ \hline  & 4.0 & 6.0 & 1 & 64 & 0.20 & 25,880 & 752 & 29,528 \\  & 4.5 & 5.0 & 1 & 64 & 0.20 & 24,880 & 742 & 28,965 \\  & 5.0 & 4.5 & 1 & 64 & 0.20 & 24,380 & 737 & 28,683 \\  & 5.5 & 4.0 & 1 & 64 & 0.20 & 23,880 & 732 & 28,401 \\ \hline \end{tabular}
\end{table} 
Table 3: SPV/WTG system: optimal sizing and economic criteria. The following statistical analysis discusses the energy production based on the average daily solar radiation (4.0 kWh/m\({}^{2}\)) and wind speed (4.0 m/s) for South Korea as a case study. However, this analysis can be extended to other cases, yielding a slight difference in daily peak solar hours per case depending on the average daily solar radiation. The annual energy contribution of the SPV array is computed based on Equation (2), SPV rated capacity is 6.0 kW \(\times\) PSH 4.01 h \(\times\) SPV derating factor 0.9 \(\times\) 365 days/year, which equals 7904 kWh. However, the tracking system plays a role in increasing the total amount of energy produced by a SPV array. The present simulation adopted a dual axis tracker that increased the total amount of energy to 11,832 kWh. Each hour, HOMER calculates the power output of the wind turbine in a four-step process. First, it determines the average wind speed for the hour at the anemometer height by referring to the wind resource data. Second, it calculates the corresponding wind speed at the turbine's hub height using either the logarithmic law or the power law. Third, it refers to the turbine's power curve to calculate the turbine's power output at that wind speed assuming standard air density. Fourth, it multiplies that power output value by the air density ratio, which is the ratio of the actual air density to the standard air density [21]. The annual energy contribution of the WTG is 1814 kWh. In addition, Figure 14 shows the monthly statistics of the output power for the WTG. It is clear that the maximum energy contribution of the WTG occurred at the first three months of the year (January-March) and at the end two months of the year (November - December), due to decreased the sunshine hours and solar radiation (as shown in Figure 6). The total annual energy production of the hybrid SPV/WTG system is 13,646 kWh (87% from the SPV array and 13% from the WTG), while the total annual energy ne  
Figure 14: Monthly statistics of the WTG output power. Figure 13: Annual energy contribution of different sources with different average solar radiation values and 4.0 m/s wind speed. is 8840 kWh, the AC load (air conditioner 91 W + lamps 40 W, operating 7 PM-7 AM) plus the DC load (BS 819 W + microwave link 80 W) multiplied by (24 h \(\times\) 365 days/year). The difference between electrical production and consumption is equal to the excess electricity of 4004 kWh/year, plus the battery losses of 753 kWh/year, plus inverter losses of 50 kWh/year. Figure 15 shows the monthly average electric production of the different power sources. The maximum energy contribution of the SPV array occurred in April and May. Meanwhile, the minimum energy contribution occurred in July.