**4. Conclusions**

Sun and marine currents are broadly available renewable resources on coastal zones, and at first sight, choosing one or the other seems unimportant; however, the generation profiles in this work indicate that MCSs have lower daily variability and, consequently, have lower energy-storage requirements. For hybrid photovoltaics–MCSs, this study indicates that for a greater participation of the MCS, the amount of required daily energy storage is lower (79%). On the other hand, the hybridization degree affects the number of daily charge–discharge cycles that the system can stand; for 0 HD in comparison to 1 HD, the cycles increase up to 46%, while for 0.2 HD, the number of cycles increases to 156%. Although this work does not include the characteristics of the ESS, depending on the type of battery or storage system, the number of cycles and the power can influence the durability of the system. However, for energy surpluses, the SMCHS with a higher MCS share can have five times higher losses in comparison to hybrid systems with higher solar shares; these losses can be avoided by using a lower dimensioning factor, although the number of days that cannot meet the demand might increase. The analysis indicates that a HD between 0.3 and 0.5 has a greater effect on the increase in days of minimum generation availability, while seasonal storage at 1 HD increases by 16% compared to using only solar energy (0 HD). Finally, the TOPSIS method for the selection of the best ESS demonstrates the relevance of electrochemical storage (batteries) in stand-alone systems, where the response time between minutes and days is more relevant than for faster technologies; on the other hand, the surplus energy generated due to seasonal variations is ideal for chemical storage in the form of hydrogen. Further studies aiming to improve the limitations of this work, such as analyses of industrial and building consumption profiles, the inclusion of the characteristics and limitations of ESSs, and economic analysis, will be published elsewhere.

**Author Contributions:** Conceptualization, J.O.-G., R.d.G.G.-H. and G.R.-S.; methodology, J.O.-G., R.d.G.G.-H. and E.P.G.-R.; software, J.O.-G. and E.P.G.-R.; validation, R.d.G.G.-H. and G.R.-S.; formal analysis, J.O.-G., R.d.G.G.-H. and G.R.-S.; investigation, J.O.-G.; data curation, J.O.-G. and R.d.G.G.-H.; writing—original draft preparation, J.O.-G., E.P.G.-R., R.d.G.G.-H. and G.R.-S.; writing—review and editing, J.O.-G., R.d.G.G.-H. and G.R.-S.; visualization, G.R.-S.; supervision, R.d.G.G.-H. and G.R.-S.; project administration, R.d.G.G.-H. and G.R.-S.; funding acquisition, R.d.G.G.-H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was developed under the framework of CEMIE-Océano (Mexican Centre for Innovation in Ocean Energy). Project FSE-2014-06-249795 financed by CONACYT-SENER-Sustentabilidad Energética.

**Data Availability Statement:** The solar irradiance database used in this paper was from database PVGIS-NSRDB provided by Solar radiation tool from Photovoltaic Geographical Information System, European Commission, (https://re.jrc.ec.europa.eu/pvg\_tools/es/#MR, 10 March 2021).

**Acknowledgments:** The authors would like to thank the Centro Mexicano de Innovación en Energía del Océano (CEMIE-Océano), the Integration to the electricity grid and energy management resources line (I-LT1), the Currents and tidal energy line for the marine current database. IPN multidisciplinary project SIP-2024 (2019-2021) and Ciencia Basica Project A1-S-15770. Jorge Olmedo-Gonzalez acknowledges to CONACYT for the scholarship.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **Nomenclature**


### **Abbreviations**


#### **Appendix A**

The appendix includes daily variations in the energy consumption and supply in the twelve months.

**Figure A1.** *Cont*.

**Figure A1.** Variations in the SMHES for the different months of the year. The variations of solar power generation (orange curve) and marine current power generation (yellow curve) are shown for each day of the year and compared with the daily demand profile (blue curve), (**a**) January; (**b**) February HD; (**c**) March; (**d**) April; (**e**) May; (**f**) June; (**g**) July; (**h**) August; (**i**) September; (**j**) October; (**k**) November; (**l**) December.

#### **References**

