## 6 Simulation Results and Discussion
### Optimization Results
#### 6.1.5 PV/Diesel/Battery System  
The initial simulation conditions considered for this study were: annual average solar radiation of 5.94 kWh/m\({}^{2}\)/day; annual average wind speed of 3.78 m/s; nominal interest rate of 12.59%; primary load demand of 76.94 kWh/day; and a project lifetime of 25 years. From the feasible system configurations shown in Table 3, the PV/diesel/battery system offers the optimal solution for the proposed system. The detailed is presented in Table 4. As depicted in Table 4, the PV/diesel/battery system could deliver the required power to the island with LCOE of 0.175 USD/kWh, NPC of USD 119,139 and emissions of 5159 kg/yr. When these parameters compared to the simulation outputs of the stand-alone diesel system, the pollutant emission gasses, NPC, and LCOE were reduced by 86.52%, 49.46% and 49.42%, respectively. The BGED, and a detailed cost summary of components, are shown in Figures 10b and 11, respectively. On the other hand, the technical performance of the PV/Diesel/battery system was simulated considering the winter and summer environmental conditions with the corresponding loads. The result shown in Figure 12 displays the detailed time series analysis of the power outputs of the PV and diesel system, battery charging and discharging, and total loads (including primary and deferrable) for the winter's day of 3 January. In the winter time, due to high solar radiation (up to 6.68 kWh/m\({}^{2}\)/day) and clearance index (up to 0.69) in the country, specifically at the study site, the PV system generates significant amounts of power from 06:00 to 18:00. The deferrable loads (6 kW) include water pumps were served from 06:00 to 11:00 when there is excess power. However, during the peak \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**System** & **PV** & **DG** & **Battery** & **Converter** & **LCOE** & **NPC** & **Operating** & **Initial** \\
**Architecture** & **(kW)** & **(kW)** & **(No)** & **(kW)** & **(USD/kWh)** & **(USD)** & **Cost (USD/yr)** & **Capital (USD)** \\ \hline PV/diesel/battery & 25 & 10 & 40 & 5 & 0.175 & 119,139 & 3196 & 55,872 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Simulation result of optimal minigrid system, architecture, and cost. Figure 11: Cost summary of PV/diesel/battery system components. loading condition (10:00 to 12:00) the diesel generator supported the PV system to fulfill the power demand and the battery charging power started to decline at 11:00. During the nighttime, from 18:00 to 06:00 the load demand receives power from battery and/or diesel generator. As shown in Figure 12, starting from 17:00 to 04:00 the battery discharged to deliver the required power to the load demand. However, from 04:00 to 06:00, when the battery was incapable of fulfilling the load demand, the diesel generator started to produce the required electricity. Similarly, the time series analysis of power outputs of the PV and diesel system, battery charging and discharging, and total loads for the summer's day of 6 July is depicted as follows in Figure 13.  
During the summer season in the study area experiences a relatively high amount of rain, with lower solar radiation (5.05 kWh/m\({}^{2}\)/day) and lower clearance index (0.48). As shown in Figure 13, the total load and the primary load are the same (overlapping) because the deferrable loads (water pumps) were neglected since the summer is rainy season in the study area. From the time series analysis, we observed that the main power source during the daytime (07:00 to 17:00) was the PV system, whereas for the remaining time, from 17:00 to 03:00 the battery system, and from 03:00 to 07:00 the diesel generator contributed the power demanded by the load. As we can observe from Figures 12, 13 and 14a, the PV  
Figure 12: Daily time series analysis for winter season. Figure 13: Daily time series analysis for summer season. power output of the summer season was relatively lower than the PV power output of the winter season.