## 5 Simulation Results and Analysis
### Calculation of Optimal Component Size of System
This is because when the PV size is insufficient, the PV power generation can only meet the current \(P_{\text{demand}}\), or the remaining power is limited, resulting in the ESS having a limited effect. When the PV sizing is in the range of 6-8 kW, the excess power of the PV system gradually increases, and ESS can function normally. However, the excess power generation is limited, and the optimal size of the battery in the ESS is small. In addition, as the SC is much costlier than the battery, even if the SC can alleviate the battery life degradation to a certain extent, it is unreasonable to use the SC in the system at this time, and configuration 3 is better than configuration 4. At this stage, as PV sizing increases, the optimal size of the battery ESS increases. When the PV sizing is above 8 kW, the surplus power of PV generation is sufficient, and the use of the ESS becomes a feasible solution for saving on the OCT of the system. Under each optimal sizing, the size of the SC also increases, indicating that under certain circumstances, a certain size of the SC in the ESS can also help reduce the OCT of the system from the perspective of mitigating battery degradation. Although the optimal size of the HESS also increases with the increase in the PV sizing, due to the system acquisition cost and battery degradation cost, the OCT decreases first and then increases. This shows that the optimal sizing is objective. Table 8 summarizes the comparative analysis of the economics of the four configurations. As listed in Table 8, the effect of each component on the system economy varies as follows (high to low): PV panel, lithium-ion battery, and SC. To improve the EFF of the system, the SC can only play a very small role; the main role is still to extend the battery life. When the size of the battery is large, its ability to mitigate battery life degradation is also limited. Referring to Figures 16 and 17, when the \(C_{\rm PV}\) is 11 kW, the \(C_{\rm SC}\) is 1.3 kWh, and the \(C_{\rm bat}\) is 48 kWh, the system can realize the MOCT. Here, the CPV values in configuration 3 and configuration 4 are consistent with configuration 2, indicating that PV sizing has a greater impact on system economics than the ESS. Figure 18 shows the simulation analysis of the HESS power under this capacity. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**System Configuration** & **1** & **2** & **3** & **4** \\ \hline Annual cost(CNY) & 11,988.1 & 9188.8 & 8051.6 & 7857.3 \\ Save cost(\%) & 0 & 23.35 & 32.81 & 34.46 \\ EFF(\%) & 0 & 59.23 & 85.53 & 86.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: System configurations for the four scenarios. Figure 17: (\(C_{\rm PV}\) = 5–13 kW) Annual OCT of different HESS sizing: (**a**) (\(C_{\rm PV}\) = 5 kW) AOCT; (**b**) (\(C_{\rm PV}\) = 6 kW) AOCT; (**c**) (\(C_{\rm PV}\) = 7 kW) AOCT; (**d**) (\(C_{\rm PV}\) = 8 kW) AOCT; (**e**) (\(C_{\rm PV}\) = 9 kW) AOCT; (**f**) (\(C_{\rm PV}\) = 10 kW) AOCT; (**g**) (\(C_{\rm PV}\) = 11 kW) AOCT; (**h**) (\(C_{\rm PV}\) = 12 kW) AOCT; (**i**) (\(C_{\rm PV}\) = 13 kW) AOCT. The trend in the annual output power curve of the HESS is consistent with the trend of \(P_{\text{demand}}\) shown in Figure 10, indicating that the lithium-ion battery can handle most of the insufficient and excess power. At this time, the system sizing can take into account both summer and winter, as well as the impact of a special climate. In addition, the discharge power of the battery tends to be stable, and the SC works more frequently. This reduces the charge and discharge rates and charge and discharge amounts of the battery to a certain extent, thereby saving on the OCT. However, the working period of the SC only accounts for 22.39% of the total period. Although the SC has a very long life, it can be charged from the grid side to maintain the state of charge at any time; however, overall, the role of the SC is limited.