What is a Ballasted Mounting System?

A ballasted mounting system is a non‑penetrating solar racking solution that secures PV modules to roofs using the weight of concrete blocks, ballast trays, or specially designed ballast frames. Unlike traditional systems that require drilling into the roof structure, ballasted systems rely entirely on their own weight to resist wind uplift, preserving the roof membrane, maintaining warranties, and eliminating the risk of leaks.

Core principle: The system uses carefully calculated ballast (typically concrete blocks, pre‑cast ballast trays, or fillable ballast containers) to counteract wind uplift forces. The combined weight of the system and ballast must exceed the uplift forces generated by design‑wind conditions, ensuring the array remains stable without any mechanical attachment to the roof structure.

1. Main Types of Ballasted Systems

2. Flat Roof Ballasted Systems

Flat roofs are the most common application for ballasted systems. Since the roof has no inherent slope, the mounting system must create an optimal tilt angle while relying on ballast to resist wind loads.

System Components:

Typical Tilt Angles:

5° tilt: Suitable for low‑latitude regions; lower wind loads, lightest system weight

10° tilt: Most common configuration; balances generation efficiency with wind resistance

15° tilt: Suitable for higher latitudes; maximum generation but heavier ballast and higher wind loads

Typical Technical Specifications:

2024 Product Developments:

Lightweight ballasted systems: Through structural optimization and high‑strength materials, some products have reduced system weight to 12‑18 kg/m², easing load concerns for older or load‑sensitive roofs

Integrated wind deflectors: Ballast trays with built‑in wind deflectors use aerodynamic principles to reduce wind uplift, potentially reducing ballast requirements by 15‑25%

Modular fast‑install systems: Pre‑assembled ballasted units require only on‑site placement and positioning, improving installation efficiency by over 30%

3. Sloped Roof Ballasted Systems

Sloped roof ballasted systems are primarily used on metal roofs (trapezoidal, corrugated). Specialized clamps attach directly to the ribs or seams of the roof panels, requiring no penetration.

System Features:

Suitable Roof Types:

Trapezoidal metal panels (rib height 30‑80 mm)

Corrugated metal panels

Standing seam metal roofs

Painted steel sheet roofs

Typical Product Specifications:

4. 2024 Ballasted System Technology Trends

1. Lightweight Design

Through topology optimization and high‑strength materials, next‑generation ballasted systems achieve 15‑25% weight reduction compared to traditional solutions while maintaining wind resistance. This is particularly important for older buildings and load‑sensitive commercial roofs.

2. Fillable Ballast Systems

Using hollow plastic or metal ballast containers that can be filled on‑site with sand, gravel, or concrete reduces transport weight to 20‑30% of traditional concrete blocks, significantly lowering logistics costs. Some products use recyclable materials to support green building certifications.

3. Intelligent Ballast Calculation

Wind tunnel testing and CFD simulation have become more widely used in ballasted system design in 2024. Differentiated ballast configurations for different roof zones (edge, corner, interior) avoid “one‑size‑fits‑all” ballasting, optimizing material usage while maintaining safety.

4. Enhanced Wind Resistance

New ballasted systems incorporate aerodynamic features such as integrated wind deflectors and air‑dynamic skirts that reduce uplift forces through airflow management, potentially reducing ballast requirements by 15‑30%. Some products have achieved FM 4478 certification for use in high‑wind regions (e.g., hurricane zones).

5. Integrated Waterproofing

EPDM pads or waterproof membranes are now commonly integrated between ballast trays and the roof surface, ensuring long‑term load distribution without damaging the roof membrane.