## 2 The Assessment of the Energy Management System for HRES
### Optimal Sizing Results  
Following the weather data and load profile collected from the site, the project lifetime of this study was considered with the value of 25 years while the discount rate and inflation rate are 7.5% and 3%, respectively. The constraint of the minimum renewable fraction of the system was set to 70%.  
According to the calculation results, the optimal configuration is defined among all the feasible configurations, in which the values of NPC and COE of the system are about 72.5 million US$ and 0.696 US$/kW, respectively. Additionally, the operation cost of the system is more than 1.9 million US$. The optimal configuration of the proposed system for the case study at Basco Island includes 5483 kW of PV, 236 units of 10 kW Wind turbines, 20,948 kW of batteries (48V DC, 4 modules, 5237 strings), 500 kW of Fuel Cells, a 750 kW Diesel generator, a 3000 kW Electrolyzer, a 500 kg H-tank, and a 1575 kW Converter. The total electric production is about 13.8 GW/year and the excess energy is around 11.2%. As can be seen from Figure 9, the monthly average electric production is illustrated. WT produces more energy in winter and spring, while solar PV generates more power in summer and autumn.  
It is indicated in Table 4 that the percentages of power production of the primary resources are 54.4% and 39.3% for PV and a wind turbine, respectively. Based on the hydrogen production as shown in Figure 10, the contribution of the fuel cell is 1.58% of total production. With the support from PV and WT as the primary power generators and fuel cells and batteries as the storage system, the use of diesel generator reduces by about 4.8%. It can be concluded that this is a high renewable fraction power system, which provided a for 91% RE. Thus, the amount of greenhouse gas emissions can be significantly decreased as shown in Table 5, compared to the case of a full diesel generator being used. Figure 11 illustrates the cash summary of all components in the optimal configuration, including capital, replacement, O&M, fuel, and salvage costs. It can be seen from Table 6 that most of the total NPC is for PV and wind turbines, accounted for 18.8% and 17.5%, respectively, due to their high investment cost. However, the highest contribution of NPC belongs to the battery with a value of around 41% because of its short life over the 25-year project. It is clear that diesel generator also has high NPC with a value of about 11% despite its low investment cost. This is because of the high cost of fuel with a value of more than US$2.4 million.  
Figure 9: Monthly average electric production.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Component** & **Capital** & **Replacement** & **O\&M** & **Fuel** & **Salvage** & **Total** \\  & **(USS)** & **(USS)** & **(USS)** & **(USS)** & **(USS)** & **(USS)** \\ \hline PV & 13,707,782 & 0 & 782,321 & 0 & 0 & 14,490,104 \\ WT & 11,800,000 & 0 & 1,683,604 & 0 & 0 & 13,483,604 \\ DG & 750,000 & 317,698 & 5,072,215 & 2,440,485 & \(-\)86,186 & 8,494,213 \\ Battery & 14,663,600 & 16,041,754 & 2,988,826 & 0 & \(-\)2,122,299 & 31,571,880 \\ Fuel cell & 1,125,000 & 0 & 415,194 & 0 & \(-\)195,842 & 1,344,351 \\ Electrolyzer & 750,000 & 0 & 0 & 0 & 750,000 \\ H\({}_{2}\) tank & 500,000 & 0 & 0 & 0 & 500,000 \\ Converter & 1,757,266 & 546,895 & 0 & 0 & \(-\)323,253 & 1,798,909 \\ System & 44,871,649 & 16,906,349 & 10,942,162 & 2,440,485 & \(-\)2,727,582 & 72,433,063 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Detailed costs of system components.  
Figure 11: The cost summary of system components.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Component** & **Production kWh/year** & **Percentage (\%)** \\ \hline Generic flat plate PV & 7,510,627 & 54.4 \\ Generic 10 kW WT & 5,421,873 & 39.3 \\ Diesel generator & 660,222 & 4.7 \\ Fuel cell & 218,542 & 1.6 \\ Total & 13,811,263 & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Electrical production.  
Figure 10: The hydrogen production of the optimal configuration.