## 3 Results and Discussions
### Photovoltaic Panel
Then, the procedure is repeated for twenty-eight (Figure 3e) and thirty PV modules (Figure 3f), the latter being the minimum number of PV modules required for covering the whole month of January. According to this analysis, thirty PV modules and a battery with 32.3 kWh of power capacity fulfill the preliminary design of the energy-production and storage system. The next step deals with the recalculation of the number of PV modules according to our new proposed energy storage system, which replaces the battery by an EL-FC. At this point, it should be noted that the software provides the output energy of the photovoltaic system (E\({}_{\text{o,PV30m}}\)), which has thirty PV modules--the optimal number for supplying the electrical demand. Part of this energy is directly used by the one-family house (D), and the excess energy (E\({}_{\text{o,PV30m}}\)) is introduced to the battery. Both provided values of energy are shown in Table 1, along with the electrical demand per day. With the efficiency of the battery (90%), its output energy (E\({}_{\text{o,BA}}\)) is calculated, which is also shown in Table 1. This value should be equal to the output energy of the fuel cell (E\({}_{\text{o,EL-FC}}\)), considering the efficiency of the electrolyzer and fuel cell [28; 29; 30; 31; 32; 33]. For that purpose, an energy balance is now performed (as shown in Figure 4) to finally calculate the value of the input energy of the electrolyzer (E\({}_{\text{i,EL}}\)). Furthermore, there is an important consideration about the state of the battery (E\({}_{\text{i,EL-FC}}\)). Figure 3: January supplied electrical demand by (**a**) sixteen PV modules for the 1 st day, (**b**) sixteen PV modules for the first week, (**c**) twenty-two PV modules for the first week, (**d**) twenty-two PV modules for the full month, (**e**) twenty-eight PV modules for the full month, (**f**) thirty PV modules for the full month. charge of the battery, since the software considers that the battery has the previous year's surpluses. However, it can continue to charge because it is not totally full. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**t** & **E\({}_{\text{o,PV30m}}\)** & **E\({}_{\text{e,PV30m}}\)** & **E\({}_{\text{o,BA}}\)** & **E\({}_{\text{i,EL}}\)** & **E\({}_{\text{i,BAe}}\)** & **E\({}_{\text{e,PVa}}\)** \\ **(Days)** & **(kWh/Day)** & **(kWh/Day)** & **(kWh/Day)** & **(kWh/Day)** & **(kWh/Day)** & **(kWh/Day)** & **(kWh/Day)** \\ \hline
1 & 14 & 6.365 & 5.729 & 17.314 & 1.731 & 19.045 \\ \hline
2 & 6.81 & 0.000 & 0.000 & 0.  
and cathode nickel flow fields. For this work, a polarization curve of this experimental electrolyzer is used for the coupling, as shown in Figure 5. The experimentation to obtain the sweep voltammetry was carried out in a potassium hydroxide solution (1 M) at 40 \({}^{\circ}\)C temperature. According to previous studies [18; 26], the most efficient coupling of the PV module with the experimental electrolyzer occurs at the maximum power point of the PV module at the highest radiation level, 1000 W/m\({}^{2}\). However, the maximum power point of the experimental electrolyzer is much lower than that of the PV module. In terms of current, the maximum current of the PV module is close to the maximum value of the experimental electrolyzer. However, it is not possible in terms of voltage, since the electric potential of the electrolyzer is much lower. For this reason, the number of cells in series in the electrolyzer must be modified until reaching the maximum power point of the PV module, whose coupling is shown in Figure 6.  
As can be observed from Figure 6, fifteen AEMWE cells are required per PV module for reaching the maximum power point of the PV module. It means that a high number of cells will be required for the ninety PV modules. This is due to the low geometric area of the electrodes (5 cm\({}^{2}\)) of the experimental lab-scale electrolyzer used.