Solar panels can be installed either on rooftops or on the ground. This article focuses specifically on the design and requirements of ground-mounted solar support foundations, which are essential for ensuring the safe, stable, and long-term operation of solar power plants.

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Importance of Solar Support Foundations

The foundation is the critical structure that transfers all forces from the solar support frame and panels into the ground.
Although foundation costs are relatively small compared to the entire solar plant investment, their reliability directly impacts the plant’s operational stability and economic performance.

Key Design Considerations

Structural Stability

The foundation must ensure:

Vertical load capacity (compression, uplift resistance)
Horizontal load capacity (wind, seismic forces)
Overall stability under various weather conditions

Seismic Foundation Bearing Adjustment Formula:
FsE = §s × Fs
Where:

FsE = adjusted seismic foundation design value
§s = seismic adjustment coefficient (refer to local seismic design codes)
Fs = static bearing design value (according to foundation design standards)

Example: In Japan, adherence to [JIS C 8955:2017] standards ensures seismic safety.

Load Conditions

The design must consider:

Solar panel size, weight, and layout
Natural forces like wind load, snow load, and seismic activity

The most common foundation types include:

Concrete Cast-in-Place Piles
Precast Concrete Piles
Steel Pile Platforms

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Types of Foundations

Concrete Cast-in-Place Piles

Mechanized drilling makes the process efficient.
Height adjustments are easier on uneven ground.
Limitations: Not ideal for weak soils, loose sand, fractured rocks, or high groundwater areas.
Winter construction can be challenging due to on-site concrete curing.

Precast Concrete Piles

Commonly use 300mm diameter prestressed concrete pipes or 200x200mm reinforced square piles.
Offer good performance even under challenging weather conditions.
Higher cost but shorter construction timelines, crucial in places like China’s inland regions.

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Construction Process Overview

Main Steps

Site Preparation: Leveling and surveying
Excavation and Positioning: Digging pits and setting embedded parts
Formwork and Concrete Pouring: Follow correct ratios and curing practices
Foundation Surface Finishing: Smooth, level, and precise placement of anchor bolts

Concrete strength requirements:

Concrete Block: ≥ MU10
Mortar Strength: ≥ M5
Concrete Grade: ≥ C20
Recommended Size: 500mm × 500mm × 400mm

Note: If soil is loose, increase foundation depth accordingly.

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Concrete Block Foundation

Environmental Considerations

When designing foundations, it’s crucial to:

Analyze soil bearing capacity και topographical characteristics.
Avoid placing one array structure across drastically different soil conditions.
Strengthen foundations if liquefaction-prone soils or newly filled soil layers are present.

Typical Reinforcement Measures:

Deep Foundations: Embed the foundation >500mm into stable soil below liquefaction depth.
Ground Improvement Methods: Vibro-compaction, dynamic compaction, or grouting to solidify loose soils.

Example: In coastal areas of China’s Jiangsu Province, dynamic compaction is often applied to stabilize loose soils before solar installation.

Conclusion

A well-designed and properly executed ground-mounted solar support foundation ensures the long-term durability, safety, and performance of a solar plant. Considering structural loads, seismic forces, construction methods, and local soil conditions will lead to higher efficiency and lower maintenance costs over the system’s lifespan.

Ground-Mounted Solar Support Foundation Design: Key Requirements and Best Practices

Table of Contents

Importance of Solar Support Foundations