What This Group Covers
At small scale this is handled with a code-based calculation and a generous safety margin. Above a few megawatts the margin becomes a material quantity, and the difference between a well-characterised wind design and a conservative one is measured in hundreds of tonnes of steel.
- Wind load derivation: terrain category, exposure, topography and site-specific factors
- Uplift zoning across an array, and why perimeter and corner zones govern structure weight
- Dynamic and aeroelastic effects on large-format modules and tracker arrays, and when wind tunnel testing is required
- Snow and ice load cases, including asymmetric drift and the practical question of whether to design for clearing
- Fatigue and serviceability checks over a 25-30 year operating life
- How the structural basis is documented for permitting, lender review and insurance
Three Configurations to Start From
Three structural strategies cover most projects:
Code-based line
Code wind calculation with standard zoning, no testing. Best for: Standard module formats, moderate exposure, inland sites. Relative cost: 1.0 (baseline).
Zoned line
Code calculation plus detailed uplift zoning and stepped fixing density. Best for: Large arrays where edge effects dominate structure cost. Relative cost: +3 to +8% steel efficiency gain.
Tested line
Wind tunnel or CFD study, validated aeroelastic data, optimised structure. Best for: Large-format modules, tracker arrays, high-exposure or complex terrain. Relative cost: +15 to +35% structure but lower tonnage.
Why structural load engineering is demanding
Structural design for solar is deceptively hard because the governing load is a pressure field rather than a weight, and it is not uniform. A structure that is comfortable in the middle of an array can be inadequate at its corner, and the difference only becomes visible when the array is large enough for zoning to matter.
- Uplift at array edges and corners can be two to three times the interior value, so a single uniform fixing density is either over-designed or unsafe
- Large-format modules behave like sails: greater area means higher absolute uplift and different frequency response than the module sizes the codes were calibrated on
- Long tracker rows introduce aeroelastic effects, including torsional flutter, that a static calculation cannot capture
- Snow drift against row edges and between rows produces local loads well above the uniform ground snow value
- Site topography – a ridge, an escarpment, a valley mouth – can raise local wind speed substantially above the regional value
- Design life of 25-30 years implies fatigue and corrosion-fatigue considerations, not just an ultimate strength check
Engineering Requirements
These are the load inputs and checks we require before a structural design is frozen. Each one has a direct effect on steel tonnage and therefore on cost.
- Basic wind speed from the governing code, adjusted for site topography, terrain category and building or array exposure
- Wind tunnel study or validated CFD where the array format, module size or terrain falls outside the code’s calibrated range
- Uplift zoning defined per array block, with structure weight and fixing density stepped by zone
- Snow load case including drift and asymmetric accumulation, with a stated position on whether clearing is planned
- Seismic case where the site requires it, including foundation and connection detailing to accommodate ductility or restraint
- Fatigue assessment for clamps, rails and bolted connections, based on the load spectrum over the design life
- Serviceability criteria: deflection limits that protect module glass, prevent clamp slip and keep trackers within drive tolerance
Selection guidance: ask for the load case table, not just the result. The cost difference between designs usually comes from which load combinations and zoning assumptions were used, and those are reviewable.
Key Parameters
| Parameter | Typical specification |
|---|---|
| Wind basis | ASCE 7, EN 1991-1-4, AS-NZS 1170.2 or your national code, with site terrain factors |
| Uplift zoning | Field, edge and corner zones; edge and corner factors typically 1.5-3.0x field values |
| Module format | Framed modules 30-35 mm; large-format and bifacial handled as a separate load case |
| Snow case | Ground snow load with drift and asymmetry factors; clearing policy stated in the design basis |
| Seismic | Spectral acceleration and importance factor per local code where applicable |
| Fatigue | Load spectrum over 25-30 years, checked at clamps, bolted connections and rail splices |
| Deflection limits | Set to protect module glass and keep tracker drives within tolerance |
| Verification | Code calculation for standard cases; wind tunnel study for large-format, high-exposure or tracker arrays |
How We Deliver It
- Load case table issued with the structural basis, so the owner, the lender advisor and the insurer can all see the same assumptions
- Zoned uplift design with stepped structure weight and fixing density across field, edge and corner zones
- Wind tunnel study coordination where the module format, terrain or array geometry exceeds the code’s calibrated range
- Fatigue and serviceability checks at clamps, splices and connections, with deflection limits set by module and drive tolerances
- Snow drift analysis with a written position on clearing, so the design case and the operating procedure agree
- Permitting support: calculation notes, load case documentation and stamped drawings where the jurisdiction requires them
Standards and Compliance
- EN 1991-1-3 / ASCE 7 snow and ice load cases matched to your design return period
- IEC 61215 / IEC 61730 for module clamping zone and frame compatibility
- EN 1090 / AISC steelwork execution classes with weld procedure qualification records
- ISO 1461 galvanizing, ISO 12944 paint systems where duplex coating is specified
- ISO 9001 production quality management, batch traceability to heat numbers
- Local building code and permitting documentation support for your jurisdiction
Quality Assurance
Every batch ships with mill certificates, coating-thickness logs and bolt records; welds follow EN 1090 or AISC execution classes. Structure warranty runs to 10 years against a 25-30 year service design life, and spare-part packages are documented so year-12 repairs do not depend on year-1 memory.
Installation and Site Productivity
The installation method is part of the technical proposal, not an afterthought. We state the equipment needed, the crew composition, the expected daily output and the tolerance acceptance criteria for every structural interface. Pre-assembled kits are labelled to your build sequence, fasteners are supplied in matched lots with torque values, and the design avoids site welding entirely. Where a project needs accelerated schedules, we plan multiple parallel work fronts and split kits accordingly.
Documentation You Receive
The paper trail matters as much as the steel. With each delivery you receive mill test certificates traceable to heat numbers; galvanizing records per batch against ISO 1461 or your specified standard; dimensional inspection reports from pre-assembly jigs; bolt and hardware lot traceability; as-built drawings where site adaptations were made; and a warranty document naming covered load cases, service design life and claim procedures. Everything is indexed, so your asset register does not depend on one engineer’s memory.
Cost and Commercial Considerations
- Wind zoning typically accounts for 5-15 percent of structure tonnage; blanket conservative assumptions can double that penalty
- Wind tunnel testing adds a fixed study cost and usually pays for itself above roughly 20 MW through reduced tonnage
- Snow drift detailing is a small cost, but a design that assumes clearing requires an operating procedure the owner must actually follow
- Large-format modules increase uplift per square metre and therefore fixing density, which is frequently underestimated at budget stage
- Fatigue detailing at clamps and splices is inexpensive to design in and expensive to retrofit after field failures
Reference Benchmarks
- Desert utility projects in the Gulf and North Africa where high-dust, high-temperature conditions and large-format modules made wind tunnel verification standard practice.
- Cyclone-exposed projects in Australia and the Philippines, where zoning and fixing density rather than section size decided survival in design events.
- Northern European and Alpine projects where snow drift against row edges exceeded the uniform ground load and drove local reinforcement.
- Coastal projects where combined wind and corrosion design reduced section capacity over time and demanded a different coating and inspection strategy.
Service Life and Maintenance Planning
Service life is a design output, not a promise. Zinc mass, fastener coating class, drainage detailing and dissimilar-metal isolation are selected against the corrosivity category of your site, and the expected first-maintenance interval is stated in writing. For aggressive environments we step the coating system up at design stage, which is always cheaper than a retrofit.
How We Control Delivery
| Stage | What we do | What you receive |
|---|---|---|
| Load basis | governing code, terrain and topography factors recorded and agreed | load case table and design basis note |
| Zoning | uplift zones defined on the layout with stepped fixing density | zoned layout drawing and fixing schedule |
| Verification | code calculation or wind tunnel study reviewed against the module datasheet limits | calculation notes or wind tunnel report |
| Connection detailing | fatigue-relevant details reviewed at clamps, splices and bolted joints | detail drawings and connection schedule |
| Production | section dimensions, hole positions and coating verified per batch | dimensional inspection and coating records |
| Handover | deflection limits, snow clearing policy and inspection criteria issued | structural basis pack and O&M criteria |
Send your site location, module datasheet and layout – we will return a load case table, a zoned structure proposal and the tonnage implications.
Guides in This Group
Wind Load Calculation & Uplift Resistance
Terrain factors, uplift zoning and fixing density that decide how much steel a site needs.
Snow Load Design for Solar Mounting Structures
Drift, asymmetry and the design consequences of committing to a clearing policy.
Wind Tunnel Testing & Aeroelastic Stability
When physical testing beats a code calculation, and how aeroelastic data changes tonnage.
Related Application Directories
This scale band is often combined with the following application groups, which cover terrain, land type and site conditions.
Frequently Asked Questions
Do we need a wind tunnel test, or is a code calculation enough?
Why do corners and edges matter so much?
How do you handle snow when the owner plans to clear it?
What deflection limits do you apply?
How is the structural basis documented for lenders and insurers?
What We Need to Quote
- Site location, topography description and basic wind speed from the governing code
- Module model, dimensions and mechanical load rating from the datasheet
- Structure type and array geometry, including row lengths for tracker arrays
- Snow load case, seismic requirement and any local code or insurer conditions
Talk to a Structure Engineer
Send your site data, target capacity and construction programme, and our engineers will return a structure concept, a quantity estimate and a costed supply package.
