Designing Effective Floating PV Sub-arrays & Channels

Introduction

Incorporating a well-designed waterway system is essential for the smooth operation of floating solar power plants. These waterways serve as critical passages for construction vessels (during installation) and maintenance boats (after commissioning). The layout of these waterways should carefully consider the distribution of photovoltaic modules within the plant, ensuring ease of access for both construction and maintenance activities.

Waterway Design Considerations

• Navigation Requirements: The waterways must be wide and deep enough to accommodate the vessels used for construction and maintenance. The waterway layout should minimize sharp turns and narrow passages to ensure safe and efficient navigation.
• Access for Maintenance: Special attention should be given to the type of foundation used for the photovoltaic modules. If a high-pile foundation (with a steel or reinforced concrete platform) is employed, maintenance can be performed directly from the platform. However, with single-pile foundations (lacking a platform), access for maintenance is typically via boat. Therefore, the layout of photovoltaic sub-arrays should consider the required space for boat travel and maneuvering, including turning radius.
• Hydrological Data: Before designing the waterway system, it is essential to thoroughly analyze hydrological and meteorological data, including:
  • The 50-year return period flood water level.
  • The 50-year return period low water level.
  • Ensure that the waterways have sufficient depth to accommodate vessels throughout the year, especially in shallower areas near the shore.
• Electrical System Integration: The layout of longitudinal and transverse waterways will divide the photovoltaic area into blocks. Ideally, each block should have a photovoltaic module capacity aligned with the electrical generation unit, minimizing the need for cable trays to cross waterways. This reduces the impact on vessel traffic and minimizes cable usage.
• Waterway Spacing: Based on research of existing floating solar power plants, it is recommended to:
  • Keep main waterways at least 400 m apart.
  • Keep secondary waterways at least 300 m apart.
  • Ensure waterway widths of at least 10 m to accommodate most construction and maintenance vessels.

Dividing Photovoltaic Sub-arrays

Once the photovoltaic modules and waterways are laid out, the photovoltaic area can be divided into sub-arrays (also known as generation units). Due to irregular water body shapes, it is common for sub-arrays to cross waterways. However, this can lead to issues:

• Cable Obstructions: Cables crossing waterways can obstruct vessel navigation.
• Increased Cable Usage: Crossing waterways often increases the length and complexity of the cable system.

To mitigate these issues:

• Rational Layout: When dividing sub-arrays, it is crucial to consider waterway crossings. Simply dividing based on capacity allocation and cable connections without considering the waterway layout can lead to sub-arrays crossing multiple waterways.
• Optimization: For sub-arrays that cross multiple waterways, adjust the layout by adding or removing photovoltaic modules to minimize or eliminate waterway crossings.

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Conclusion

A well-designed waterway system is vital for the construction and maintenance of floating solar power plants. By carefully considering the needs of vessels, optimizing the placement of photovoltaic sub-arrays, and minimizing the impact on navigation, the overall efficiency and long-term operation of the plant can be significantly enhanced. The next sections will explore the layout of additional critical components within floating solar power plants, such as transformer platforms and the overall power collection system.