Flexible Solar Mounting Structures: A Professional Overview
As solar energy projects expand into challenging terrains-such as mountainous areas, water surfaces, landfills, and agricultural complementary sites-flexible solar mounting structures have emerged as a highly efficient alternative to traditional rigid steel frameworks. This article provides a practical, multi-angle introduction to the design principles, nonlinear behavior, load considerations, and key performance indicators of flexible PV support systems.
1. What Is a Flexible Solar Mounting Structure?
A flexible solar mounting system is a cable-supported structure that uses pre-stressed steel cables (ropes) instead of rigid beams to support photovoltaic panels. Unlike conventional fixed-tilt or tracking systems, flexible mounts rely on tensioned cables spanning between steel columns or concrete foundations. This design significantly reduces steel consumption, shortens installation time, and enables large-span layouts.
2. Core Design Standards
To ensure safety and reliability, flexible PV support design should reference multiple technical codes, including but not limited to:
Technical Specification for Cable Structures (JGJ257)
Code for Design of Photovoltaic Module Supports
Load Code for the Design of Building Structures (GB50009)
Standard for Design of Steel Structures (GB50017)
Code for Design of Photovoltaic Power Stations (GB 50797)
Technical Code for Support Foundations of Solar Power Stations
Technical Specification for Cable-Supported PV Supports
Design Specification for Large-Span Cable-Pole PV Structures
Technical Guidelines for Design and Installation of Flexible PV Supports
These standards collectively guide material selection, load calculations, and structural verification.
3. Geometric Nonlinearity and Analysis Methods
Flexible supports are tensioned cable systems with pronounced geometric nonlinearity. Structural analysis must be divided into two stages:
Initial form-finding stage – achieving equilibrium under self-weight and pre-stress.
Load application stage – analyzing deformation and internal force redistribution under external loads.
Key modeling considerations:
Cables: use cable elements (tension-only, no compression).
Steel columns/beams: use beam elements.
Ground anchor wires: use tension-only truss elements.
PV panels: use truss or shell elements.
Because flexible structures undergo large displacements and rotations, the small-deformation assumption fails. Geometric nonlinearity must be included. The Newton-Raphson iteration is commonly used, but convergence issues (e.g., zero tension or singular points) may arise. The arc-length method or damped iteration is recommended for unstable or slack cable conditions.
4. Load Types and Special Considerations
Permanent loads, wind, snow, construction/maintenance loads, temperature effects, and seismic actions must all be considered.
Cable pre-stress determination
Pre-stress must balance sag control and breaking strength. Overly low pre-stress increases deflection; overly high pre-stress risks cable rupture.
Wind load handling
Tilt angle < 40°: Use overall shape coefficients from *NB/T 10115-2018*, Table 4.1.3-1.
Tilt angle ≥ 40°: Use 1.3 envelope coefficient from GB 50797 (2024).
For flexible supports with >7 rows of panels, reduction factors (0.85) may apply as per *NB/T 10115-2018*, provided the average positive coefficient ≥0.6 and negative coefficient ≤ -0.9.
Wind-induced vibration
Per *NB/T 11813-2025*, Article 4.3.5:
Small-span single-layer cables: 1.2–1.5
Double-layer cables: 1.3–1.9
Large/ultra-large spans: determine via numerical simulation or wind tunnel testing.
Temperature effects
Both temperature rise and drop cases must be analyzed, with material linear expansion coefficients verified by testing if necessary.
5. Key Design Indicators
Stress ratio for steel members and cables
Cable stress ratio should be controlled between 0.8 and 0.85 of the breaking strength.
Cable deflection limits
Deflection directly affects panel angle and introduces mechanical tension on modules. Based on operational experience, flexible cable deflection is generally controlled at L/50 to L/30 (L = span length).
General projects with no special flatness requirements: L/40 ~ L/30
High-precision projects (e.g., bifacial modules, high flatness requirements): L/50 (stricter control) to reduce efficiency loss and long-term durability risks.
Lateral displacement of columns
Should comply with steel structure design standards to prevent excessive sway under wind or seismic loads.
6. Practical Research Value
Flexible solar mounting structures offer three major research and application advantages:
Material efficiency – reduces steel usage by 30–40% compared to rigid structures, lowering carbon footprint and costs.
Terrain adaptability – ideal for跨度 up to 50+ meters over ponds, valleys, or existing agriculture without dense foundations.
Construction speed – pre-stressed cable systems can be tensioned quickly with fewer heavy machinery requirements.
However, challenges remain: complex nonlinear analysis, wind-induced fatigue, cable anchorage durability, and long-term pre-stress loss require further field monitoring and refinement of design codes.
About us:
Longsun Green – a professional solar mounting manufacturer – provides reliable and customized flexible PV support solutions for global projects.
📧 Email: amber@longsungreen.com
🌐 Website: www.longsungreen.com
