CSLB C-46 Solar ContractorPhotovoltaic System InstallationEasy
A solar installer is mounting PV modules onto a flat commercial roof using a ballasted racking system. What is the primary method used to prevent the array from being uplifted by high winds?
- ADistributing concrete blocks or other heavy materials on the racking.
- BApplying specialized adhesive to bond the modules directly to the roof membrane.
- CAnchoring the racking system directly into the roof structure.
- DUtilizing aerodynamic module skirts to reduce wind resistance.
Show answer & explanationAnswer & explanation
Correct answer: A. Distributing concrete blocks or other heavy materials on the racking.
Ballasted racking systems rely on the weight of ballast (e.g., concrete blocks, pavers) to counteract wind uplift forces. This method avoids penetrations into the roof membrane, which is often preferred for flat commercial roofs.
Why the other options are wrong
- B. Direct adhesion is a less common and typically not the primary method for large commercial ballasted systems.
- C. This describes a mechanically attached system, not a ballasted system.
- D. Aerodynamic skirts can reduce uplift, but the primary method for a ballasted system is weight.
Ballasted Racking Wind Resistance
Ballasted racking systems resist wind uplift forces by using the weight of non-penetrating ballast materials, such as concrete blocks, distributed across the racking structure.
- Avoids roof penetrations, preserving roof warranty.
- Ballast weight is calculated based on wind zones, array height, and roof characteristics.
- Requires careful distribution of weight to prevent roof damage.
Memory trick: Ballast Blocks Blow-Away.