Mounting Structure
A mounting structure (also called a racking system) is the engineered framework that supports solar panels on a roof, ground surface, or canopy. It ensures that modules are securely fixed, properly angled, structurally stable, and able to withstand environmental loads such as wind, snow, thermal expansion, and seismic conditions.
In solar PV design, the mounting structure is a crucial component because it directly affects energy production, installation cost, system durability, and AHJ compliance. Modern layout tools—such as Solar Designing—integrate mounting structure parameters into the automated layout process to produce accurate and buildable solar designs.
Key Takeaways
- A mounting structure is the engineered framework that secures and positions solar panels.
- Proper mounting ensures structural safety, energy optimization, and code compliance.
- Structures vary across roof-mount, ground-mount, trackers, and canopy systems.
- Mounting structure design directly influences shading, performance, and installation cost.
- Modern design platforms integrate racking into automated layouts to improve accuracy and speed.
What Is a Mounting Structure?
A mounting structure is the physical system that holds solar panels in place and ensures proper orientation, tilt, spacing, and load distribution. It is designed to:
- Transfer loads safely into the roof or ground
- Maintain correct tilt and azimuth
- Provide ventilation and thermal expansion tolerance
- Prevent uplift from wind forces
- Resist corrosion and long-term weathering
- Meet local building, engineering, and fire codes
Mounting structures differ based on installation surface (roof, ground, carport, canopy), module type, wind region, roof material, and project scale.
Related foundational terms include Mounting Structure Design, Racking Layout, and Solar Layout Optimization.
How a Mounting Structure Works
Mounting structures function by providing a stable, engineered interface between the solar modules and the surface they are installed on.
1. Structural Attachment
For rooftops, attachments are fastened into rafters, purlins, or decking.
For ground-mounts, posts or foundations secure structures into the soil.
2. Rails or Rail-less Platforms Hold the Modules
- Rails provide a continuous support surface.
- Rail-less systems use direct attachment points to reduce material and labor.
3. Hardware Locks Modules in Place
Clamps, bolts, and mid/end clamps secure modules while allowing thermal expansion.
4. Tilt and Azimuth Are Set Based on Design
Tilt frames adjust the orientation to maximize production—see POA Irradiance.
5. Load Transfer & Wind Resistance
Mounting systems must withstand uplift, downforce, and lateral forces—often checked using Wind Load Calculation and Snow Load Calculation.
6. Electrical Bonding and Grounding
Most systems include integrated grounding paths for electrical safety.
Types / Variants of Mounting Structures
1. Roof-Mount Structures
Used in residential and commercial installations.
Sub-types include:
- Rail-based racking
- Rail-less mounting
- Ballasted (for flat roofs)
- Hybrid systems
- Clamp-on standing-seam mounts
2. Ground-Mount Structures
Common in C&I and utility-scale projects.
Variants:
- Fixed-tilt ground-mounts
- Pole mounts
- Utility-scale steel structures
- Seasonal tilt-adjustable systems
3. Solar Trackers
Single-axis or dual-axis trackers that follow the sun’s path.
See Solar Tracker.
4. Carport & Canopy Structures
Mounting structures installed above parking lots or walkway shelters.
5. Bifacial-Optimized Structures
Raised structures designed to maximize rear-side irradiation—see Bifacial Solar Panel.
How Mounting Structures Are Measured
1. Tilt Angle
Often determined using tools like the Sun Angle Calculator or local irradiance analysis.
2. Structural Load Capacity
Measured in pounds (lbs), kPa, or PSF (pounds per square foot) for:
- Wind loads
- Snow loads
- Live loads
- Dead loads
3. Module Spacing & Row Gap
Impacts shading, maintenance access, and energy production.
4. Material Strength
Typically measured in tensile strength, yield strength, and corrosion resistance ratings.
5. Foundation or Attachment Strength
Testing values or engineering specs ensure safe load transfer.
Practical Guidance for Solar Designers & Installers
1. Select mounting structures based on roof type
Standing-seam metal roofs: clamps
Shingle roofs: flashed lag bolts
Flat roofs: ballasts
2. Confirm load engineering early
Use wind and snow engineering tools and ensure compliance with local AHJ requirements.
See AHJ Compliance.
3. Ensure proper spacing for ventilation
Modules must have airflow to maintain thermal efficiency.
4. Avoid shading caused by the mounting geometry
Use Shadow Analysis to minimize shading from ridges or elevated structures.
5. Plan for O&M walkways
Especially in commercial and flat-roof systems.
6. Integrate racking details into proposal and permit workflows
SurgePV’s tools streamline this process:
7. Ensure proper grounding and bonding
Critical for safety and NEC compliance.
Real-World Examples
1. Residential Pitched Roof
A 10 kW system uses aluminum rail-based racking with flashing attachments to mount 24 modules at roof pitch.
2. Commercial Flat Roof
A ballasted mounting structure supports 800 modules with 10° tilt and clear O&M pathways.
3. Utility-Scale Ground Mount
Steel fixed-tilt structures support 15,000 modules arranged in long rows with optimized spacing for minimal shading.
.svg)
