Foundation Types for Ground Solar Systems
Ground solar mounting systems position solar panels on the ground, in contrast to rooftop installations. Rooftop systems integrate with the existing building structure, while ground panels depend on robust foundations to withstand wind, weather, and time. Your choice of foundation type impacts installation cost and speed, along with the overall stability and longevity of the solar array. In this article, you'll learn about different types of ground solar system foundations and related knowledge.
What Is a Ground-Mount Solar System?
A ground-mount solar system, as the name implies, positions solar panels on frames secured to the ground. This contrasts with mounting panels on a rooftop or another existing structure. The metal framing supports the panels at an angle, maximizing exposure to sunlight throughout the day.
Choosing the Right Foundation for Your Ground Solar System
The foundation serves as the crucial link between the solar racking system and the earth, providing the necessary support and anchoring to resist uplift, lateral forces, and settling. Several foundation options exist, each with its own advantages and suitability for different soil conditions and project scales.
1. Concrete Footings (or Concrete Piers)
Concrete footings, also called concrete piers, involve pouring concrete into excavated holes. Metal anchors or embeds are then set into the concrete to connect to the racking system.
1.1 Advantages
● High Stability: Extremely stable and resistant to movement, even in challenging conditions.
● Suitable for Uneven Terrain: Can be adapted to rocky or uneven ground.
● Long Lifespan: Concrete is a very durable material.
1.2 Considerations
● Longer Installation Time: Requires excavation, concrete pouring, and curing time.
● Higher Labor Costs: More labor-intensive than other methods.
● Permanent: Difficult to remove or relocate.
2. Ground Screws
Large, screw-like anchors are driven into the ground using specialized equipment. The racking system then attaches to the top of the screw.
2.1 Advantages
● Fast Installation: Significantly faster to install than concrete footings.
● Less Soil Disturbance: Minimal excavation required.
● Suitable for Softer Soils: Works well in sandy, loamy, or clay soils.
2.2 Considerations
● Not Ideal for Rocky Ground: Difficult or impossible to install in very rocky soil or bedrock.
● Holding Capacity Varies: Holding strength depends on soil conditions. Soil testing is important.
3. Driven Piles
Steel beams (often I-beams or H-beams) are driven directly into the ground using a pile driver. This creates a very strong and deep foundation.
3.1 Advantages
● High Load Capacity: Can support very large and heavy solar arrays.
● Fast Installation (for large projects): Efficient for large-scale installations.
● Suitable for Various Soil Types: Can be used in a wide range of soil conditions.
3.2 Considerations
● Specialized Equipment: Requires a pile driver, which adds to the initial cost.
● Noise and Vibration: Pile driving can be noisy and create vibrations.
● Best for Larger Projects: Often more cost-effective for utility-scale solar farms.
4. Ballasted Systems
These ballasted systems use pre-cast concrete blocks or other heavy weights to hold the solar array in place. They don't penetrate the ground.
4.1 Advantages
● No Ground Penetration: Ideal for sites where digging is restricted (e.g., landfills, brownfields, rocky areas).
● Easy to Decommission: Can be removed and relocated relatively easily.
● Minimal Site Preparation: Requires less site preparation than other methods.
4.2 Considerations
● Weight Requirements: Requires careful engineering to ensure sufficient weight to resist wind uplift.
● Drainage: Proper drainage is important to prevent water buildup around the ballast blocks.
● Suitable surface: Need a relatively flat and stable surface.
Before You Begin
● Soil Testing: Before choosing a foundation type, it's important to conduct soil testing. This determines the soil's composition, bearing capacity, and other factors that influence foundation design.
● Local Regulations: Building codes and permitting requirements vary by location. You'll need to ensure your foundation design complies with local regulations.
● Engineering: For any ground-mounted solar system, it's important to consult with a qualified structural engineer. They will design the foundation to meet the specific needs of your project and ensure its long-term stability and safety!