A Quick Guide for Solar Developers
When building a ground-mount solar projects, there are two primary solutions available on the market: ground screws and concrete foundations. This guide provides a detailed analysis of the differences, pros and cons, and ideal application scenarios for each, helping you make an informed choice.
Ground Screws: Fast & Removable
Ground screws are galvanized steel helical piles that are mechanically driven—not drilled—directly into the soil.
How it works: Steel piles are screwed into the ground using hydraulic torque motors, with no excavation or concrete required.
✅Pros
· No concrete required, no need to wait for curing—allows for immediate installation and accelerates project timelines.
· Minimal soil disturbance—no excavation needed, no excess soil to dispose of, and low environmental impact.
· Removable and recyclable—the steel components can be extracted and reused at the end of their service life.
· Excellent performance on sloping terrain—no need for leveling or prepared base layers.
❌Cons
· Not suitable for rocky ground or shallow bedrock—subsurface obstacles can limit the installation depth of helical piles.
· Requires specialized installation equipment and skilled operators.
· During the installation process, the galvanized coating must be protected to prevent corrosion at any points where it might be scratched.
Concrete Foundations: Stable & Traditional
· Concrete foundation (also called cast-in-place piles) are the long-standing industry standard, formed by drilling holes, placing rebar cages, and pouring concrete.
· How it works: Holes are augured, rebar is set, and concrete is poured to form rigid piers that cure over time.
✅Pros
· High rigidity and high compressive strength—offering excellent resistance to overturning moments.
· Superior uplift resistance—field-tested and proven under extreme high-wind conditions.
· Better adaptability to rocky strata and varied soil conditions compared to helical piles.
❌Cons
· Requires a relatively long curing period—typically 7 to 28 days—before the installation of racking systems can begin.
· Involves more extensive excavation and site restoration work.
· Constitutes a permanent structure—difficult and costly to remove or relocate.
When to Choose Which?
Pick ground screws:
Most utility-scale solar, agrivoltaics, sloped land, tight interconnection deadlines, leased land.
Pick concrete foundations:
Rocky bedrock sites, high-wind hurricane zones, heavy tracker loads, local code mandatory concrete requirements.
UISOLAR Tip
Foundation design must always be based on a qualified geotechnical survey and site-specific wind and snow load analysis. There is no one-size-fits-all answer—soil conditions, climate, and local codes all shape the right choice.
UISOLAR provides complete mounting system design services, including ground screw layout, connection details, and structural calculations tailored to your site conditions.
Conclusion
Ground screws are the preferred option for most modern solar projects—delivering speed, sustainability, and flexibility that align with today's project demands. Concrete foundations, however, remain the reliable choice for high-risk sites with rocky soil, extreme wind loads, or strict local code requirements.
Not sure which is right for your site? Reach out to UISOLAR for a customized foundation recommendation.