## 5 Conclusions  
The obtained results demonstrate that the introduction of a hydrogen and photovoltaic system into a domestic application is a viable option to supply energy without any connection to the grid. For isolated locations from the electricity grid, this method of coupling is a good approach to produce energy. The design takes place in Spain, but the procedure developed in this work can be generally used elsewhere, since it implies the use of a commercial PV software and available general information. The present study is based on a novel and simple procedure to design a photovoltaic-hydrogen system, but the obtained sizing results of the different components are in good agreement with previous studies, which typically used more complex models or experimental procedures, which supports the information reported here. An initial solar PV array is calculated by using the commercial software PV-SYST 7.0, which considers the energy storage within a battery. However, in the next steps, the battery is replaced by the electrolyzer-fuel cell system because the battery has a short lifetime and charge/discharge cycles. Furthermore, the battery components are less friendly with the environment. In this way, the study obtains the most sustainable way of producing energy in an isolated location. These results demonstrate that it is possible to use hydrogen for a self-sufficient energy system for low-scale domestic application as an alternative method to conventionally used batteries. This study leads to an increase in the final area of the solar PV array to a final value of 65.325 m\({}^{2}\), which is feasible within the standard dimensions of the roof of a house and agrees well with previous results published in the literature. The optimal final dimensions of the hydrogen tank were found to be 2.4 \(\times\) 0.7 m at 30 bars as storage pressure, being the selected material carbon steel. These dimensions are close to the dimensions of the diesel tank that nowadays is commonly being used at home. In addition, the final number of cells in the electrolyzer has been calculated according to the commercial AEMWE units available in the market. A PEM fuel cell is chosen in order to achieve the maximum power required in the application. All the equipment can be laid down in any one-family house. This paper has demonstrated that the EL-FC system needs only 12827 \(\upxi\) of initial capital with an LCOE of 0.541 \(\upxi\)/kWh, which are competitive values with the results reported in the bibliography. In addition, this system is sustainable with the environment because it has a lower environmental impact than the conventional system. We hope that the scientific community continues to push up the development of the anion exchange membrane water electrolyzer coupling with renewable sources. The following are available online at [[https://www.mdpi.com/article/10.3](https://www.mdpi.com/article/10.3)]([https://www.mdpi.com/article/10.3](https://www.mdpi.com/article/10.3)) 390/app11209582/s1, Figure S1: P&ID. Figure S2: I-V characteristic curves of the Solarte_SST72_110_24_106W module. Figure S3: I-V curve of the experimental AEMWE of 50 cm\({}^{2}\). Figure S4: I-V characteristic curves of the Solarte_SSW72_08_108 Wp module. Figure S5: January supplied electrical demand by (a) three PV strings for the 1 st day, (b) three PV strings for the first week, (c) four PV strings for the first week, (d) four PV strings for the full month, (e) five PV strings for the full month. Figure S6: Datasheet of Fegen-1020 ACS fuel cell. Figure S7: Mijaley monogram. Figure S8: Hydrogen tank with dimensions. Table S1: Output photovoltaic panel energy and electrolyzer energy. Table S2: Hydrogen initial conditions. Table S3: Vain Method. Table S4: Economical evaluation of both systems: conventional system with battery and electrolyzer-fuel cell system without battery.