Technical Guide

Ground Mount Solar
Racking: Buyer's Guide

Foundation types, steel specification, wind load design, and row spacing — everything needed to evaluate and specify a ground mount racking system from China.

Ground Mount Racking Overview

Ground mount solar racking is used for utility-scale, commercial, and agricultural solar installations where rooftop space is unavailable or insufficient. The system transfers module weight and wind/snow loads to the ground via a steel structure and foundation system.

C-steel (carbon steel) ground mount is the dominant product type for commercial and utility installations, offering higher strength-to-cost ratio than aluminum for large spans. OmniSol supplies Q355B and Q235B structural steel profiles with hot-dip galvanized (HDG) or ZnAlMg coating for corrosion resistance in outdoor environments.

The three main design decisions are: (1) foundation type — driven pile, screw pile, or concrete ballast; (2) steel coating system — HDG or ZnAlMg; and (3) tilt angle — optimized per project latitude and shadow constraints.

Foundation Types

Driven Pile (Ground Screw or H-Pile)

Cost: Low–MediumReversible

Steel pile driven directly into the soil using a hydraulic driver or pile hammer. No concrete required. The dominant foundation method for utility and commercial ground mount.

Soil suitabilityClay, loam, sandy clay, compacted fill. Requires geotechnical assessment for rock, loose sand, or expansive soils.

Installation speedVery fast — 100–200 piles/day per machine

OmniSol notePile length and diameter determined by soil bearing capacity and wind uplift force. OmniSol provides pile specification table per project wind zone and soil class.

Concrete Ballast (Surface Mount)

Cost: Medium–HighPermanent

Pre-cast or cast-in-place concrete blocks anchor the structure without soil penetration. Used where soil conditions prohibit driven piles or where the installation is on hardstand or rooftop.

Soil suitabilityAny surface including rock, hardstand, gravel. Also used on flat concrete rooftops.

Installation speedModerate — concrete pour or delivery schedule adds time

OmniSol noteConcrete mass calculated per wind uplift. OmniSol provides ballast weight and block sizing per project wind speed and tilt angle.

Helical Screw Pile

Cost: MediumReversible

Screwed into the ground using a torque drive head. Suitable for softer soils or where vibration from driven pile is restricted (near existing structures).

Soil suitabilitySoft to medium clay, silty soils. Not for loose dry sand without geotechnical review.

Installation speedModerate — slower than driven pile but no vibration

OmniSol noteInstallation torque correlates to bearing capacity. Helical screw piles can be load-tested on-site before array installation.

HDG vs ZnAlMg Coating — Which to Choose?

Hot-Dip Galvanized (HDG)

Standard 85 µm zinc coating (AS/NZS 4680 / ISO 1461)
Proven 25+ year design life in C2–C3 corrosion categories
Lower cost — the standard specification for most projects
Not recommended for C4+ environments (within 500m of ocean, industrial)

ZnAlMg — ZM275 (Zinc-Magnesium-Aluminum)

3× corrosion resistance of equivalent HDG thickness
Superior cut-edge protection — important for punched holes and cut ends
Recommended for coastal, humid, or tropical environments
~15–20% cost premium over HDG

OmniSol Ground Mount — Standard Specifications

Steel grade	Q355B structural steel (yield strength 355 MPa) or Q235B for secondary members
Corrosion protection	Hot-dip galvanized (HDG) to AS/NZS 4680: minimum 85 µm; or ZnAlMg ZM275 coating (3× corrosion resistance of HDG)
Wind load design	Up to 60 m/s per AS/NZS 1170.2, ASCE 7-22, or EN 1991-1-4 — project-specific calculation provided
Snow load design	Per AS/NZS 1170.3, ASCE 7-22 Chapter 7, or EN 1991-1-3 — included in engineering report
Tilt angle	Fixed: 10°–35° standard; custom angles available. Tracking: single-axis option available on request
Module compatibility	All standard 60/72-cell and commercial bifacial modules. Custom purlin spacing for large-format modules (>2.2m)
Row spacing	Calculated per project latitude/longitude to eliminate winter shadow overlap. OmniSol provides CAD layout as part of engineering support
Warranty	12-year product warranty; 25-year structural design life