# Innovative Strategies for Combining Solar and Wind Energy with Green Hydrogen Systems
## 5 Discussion
### Renewable Energy Sources
#### 5.1.1 Solar-Powered Hydrogen Production System  
PV/H2 technology is a green H2 generation method powered by the solar system, which creates electricity to fuel the electrolysis unit. The PV/H2 system is the most commonly employed technique for producing green H2 due to its low cost, superior efficiency, and ease of implementation. This technology has been experimentally tested in several places and weather situations. Another research investigation found that utilizing a photovoltaic tracking system provided the best results but at a higher cost than a conventional PV system, while using a concentrated PV system increased efficiency when compared to a classical PV system. Another model-based investigation yielded similar results to an empirical investigation. A review of a photovoltaic system-based maximum power point tracking (MPPT) revealed that the performances were nearly identical to those of a PV system with or without MPPT, although the cost was somewhat higher when employing MPPT. Furthermore, it was established that the rate of H2 production was proportional to MPPT efficiency [79].  
Research has shown that combining the PV/H2 system with PEM electrolysis has yielded promising results, with efficiency steadily improving over time. In 2008, just 6% performance was reported utilizing the PV/H2 combination, with a high production cost of approximately 40 USD/kg [80]. Research aims to improve PV/H2 efficiency, productivity, and cost-effectiveness. In reality, in 2010, the efficiency was increased to 12.4% by adopting direct connectivity between the photovoltaic system and the electrolytic unit. The production cost of H2 has lowered from 40 USD/kg in 2008 to 3.4 USD/kg in 2022. The outcome is because of the operating voltage system, which is constantly accessible from the PV system to power the electrolysis. Several studies have found that PV/H2 systems are better suited for remote places than electrolysis. Furthermore, because PV panels are more efficient than horizontal panels, they have an impact on H2 production. The PV/H2 system can generate both H2 and power through a fuel cell, making it ideal for nighttime or wintertime use [81].  
When there is little or no solar radiation to generate the electricity required for electrolysis, a fuel cell can be acquired to power an electrolysis machine. Utilizing grid/H2 for H2 generation is less expensive than utilizing grid/PV/H2 or PV/H2, according to a study of the costs of various green sources for electricity production. In actuality, the expenses for grid/H2, grid/PV/H2, and PV/H2 are, respectively, 5.5, 6.1, and 12.5 USD/kg [82]. Because power transportation is relatively expensive, PV systems and wind energy are advantageous in rural places where the traditional grid is not deployed. The initial cost has been determined to be dependent on the cost of the land and the installation of the PV system. A high output of H2 can be provided by increasing the efficiency of the PV/H2 system, which is particularly appropriate in remote places due to the significant potential of solar energy in these areas. This has led to the introduction of bifacial solar panels, which first increase H\({}_{2}\) generation and subsequently improve efficiency [83]. As a result, H\({}_{2}\) generation increased to 4.2 g/h/m\({}^{2}\) from 3.7 g/h/m\({}^{2}\) in the case of monofacial solar panels, while the efficiency of bifacial solar panels reached 13.5% as opposed to 11.55%.