# Probabilistic Analysis of Low-Emission Hydrogen Production from a Photovoltaic Carport
## 3 Components of the Low-Emission Hydrogen Generation System
### Hydrogen Electrolyzer  
Many European and global companies are developing and marketing products for the production, storage and use of hydrogen in various industries and transport, as could be seen at the Hydrogen Technology Expo in Bremen in 2023. Exhibitors of electrolyzers of various types used to produce hydrogen presented their products at the fair. These were European, American and Chinese companies, although the latter's participation in the fair was not very extensive. The latest electrolyzers are offered in PEM [74; 75], alkaline [76] and the latest AEM [77] technology. The appearance of an electrolyzer stack itself and a stack built in a compact housing are shown in Figure 5a and 5b, respectively.  
For engineering, educational and scientific purposes, it is crucial that some electrolyzer manufacturers offer ready-made 3D models of the electrolyzers themselves, the water preparation station, the hydrogen drying station and even the rack cabinet in which these elements can be installed. The 3D models of individual components of the hydrogen generation system prepared in the rendered version appear like the photos of the real objects (Figure 6). This approach, called rapid prototyping, greatly shortens the design time of a hydrogen generation system [78].  
Figure 4: Photovoltaic export with bifacial panels with a peak power of 6.36 kWp.  
Figure 5: Electrolyzers: (**a**) multi-cell electrolyzer stack, (**b**) electrolyzer module with built-in multi-cell stack.  
Figure 6: Three-dimensional models: (**a**) electrolyzer module, (**b**) water preparation station and (**c**) hydrogen dryer [79].  
The choice of an electrolyzer for a hydrogen generation system powered by a photovoltaic carport is not accidental. Water electrolyzers for hydrogen production are manufactured employing various technologies. The ones that are most important include alkaline electrolyzers, with a PEM membrane [80], an AEM membrane [81] and high-temperature SOE [82]. AEM electrolyzers are characterized by the greatest flexibility in terms of load variability.  
The lifecycle of the presented AEM electrolyzer stack, as with all electrochemical devices, is reduced in the event of frequent starts/stops. As the field experience and the operational data increase, the manufacturer recommends its customers limit the electrolyzer operating cycles to a maximum of five on/off cycles per day and one on/off cycle per hour. This helps to ensure the durability of the electrolyzer. The electrolyzer works most effectively and is most durable when used continuously [83]. However, the modular design of the presented electrolyzers and the energy management system is perfectly suited to adapt to changing renewable energy supplies or changing demand. Individual electrolyzers can be charged from 60 to 100%, and the combination of multiple electrolyzers allows for any required flow rate of produced hydrogen [84]. If the hydrogen demand is sporadic throughout the day, adding an appropriately sized buffer tank can minimize the electrolyzer on and of cycles. It was decided to place the rack cabinet with electrolyzers and the energy storage in a container, as shown in Figure 7. Solid Edge version 2024 was used for modeling. To accommodate the rack cabinet with the hydrogen generation system and a small energy storage with a capacity of 10 \(\div\) 15 kWh, a 10-foot ISO shipping container was used.