# Performance Analysis of a PEMFC-Based Grid-Connected Distributed Generation System
## 3 Overview of Hybrid Microgrid System

Table 3: PV module (polycrystalline cells) specifications. Figure 5: Monthly solar irradiance. Equation (18) expresses the total annual produced PV energy. By this calculation, the annual average produced energy profile is plotted and illustrated in Figure 7; the total annual PV energy corresponds to 1335.05 kWh. Figure 8 depicts the hourly total produced PV output energy. It can be extracted that generation is higher at noon than at the other times. The system is established and designed to operate both independently and connected to the grid. The system can be fed by the utility grid, with the aim of hybrid inverter operation when the state of charge (SoC) of battery bank is lower than desired level, as this means the stored energy is not able to meet the load demand. When the battery bank meets the load requirement, the system continues to operate independently of the grid. This energy management scenario in these DG systems ensures the flexibility and sustainability of the systems. Figure 6: Geographic location of the faculty building and solar positions. Figure 7: Total produced PV output energy. As seen in Table 4, the daily energy requirement was calculated as 14,360 kWh. In this case, the annual average energy demand is 3791.04 kWh. Since the total annual energy demand is 3791.04 kWh, the 2029.497 kWh of energy that cannot be met by production can be supplied from the grid via the hybrid inverter. \[Ah=\frac{nkE_{demand}}{v_{DC}DoD} \tag{19}\]  
where \(n\) represents days of autonomy (\(n=2\)), \(DoD\) is the maximum depth of discharge (\(DoD=40\%\)), \(v_{DC}\) is DC bus voltage (\(v_{DC}=24\) V), \(E_{demand}\) is total energy demand, \(k\) is the temperature correction factor (\(k=1.04\)). Six batteries of 120 Ah each are connected in series and parallel as shown in Figure 2 to obtain nominal 24 V and a total power of 14.4 kWh. The system components are installed in the \"Renewable Energy Laboratory\" within the Faculty. The lighting and the \"plug and play\" loads are connected to the DG system. The lighting (armature) loads are shown in Figure 9. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Loads** & **\#** & \begin{tabular}{c} **Nominal Power** \\ **[W]** \\ \end{tabular} & \
\begin{tabular}{c} **Hours of** \\ **Use/Day** \\ \end{tabular} &
\begin{tabular}{c} **Energy Use/Day** \\ **[Wh/Day]** \\ \end{tabular} \\ \hline Air & 1 & 560 & 5 * & 2800 \\ Conditioning & 1 & 400 & 2 & 800 \\ Electrolyzer & 1 & 48 & 10 * & 5.760 \\ Lighting & 12 & 250 & 10 & 5000 \\ PC & 2 & 2.616 & & 14,360 \\ Total & & & & \\ \hline \hline \end{tabular}  
* Discrete time.  
\end{table} 
Table 4: The load profile of the laboratory. Figure 8: Total produced hourly PV output energy (kWh). The annual average energy produced from the wind turbine and PV modules is 1563.543 kWh. The PEMFC can generate 198 kWh of energy per year when we estimate that it produces 3 h of average power per day. In this case, the total energy produced from the hybrid microgrid is 1761.543 kWh. By means of the electrolyzer in the system, the hydrogen demand of the hydrogen fuel cell stack can be met. The hydrogen produced by the electrolyzer is stored in the metal hydride canister. The charge pressure of the metal hydride canister is 5 bar, and the discharge pressure is 2-5 bar. The weight is 14 kg, the and capacity is 1500 lt. The empty canister can be fully filled in 50 h. A PEM-type hydrogen fuel cell stack is used in the system. The stack in the system can run for 8 h with a full hydrogen canister at a 250 W average. In order for the hydrogen fuel cell stack to operate at a maximum power of 1200 W, it should be supplied with 13 L of hydrogen per minute. The output flow of the electrolyzer used in the system is 510 mL per minute.