CSLB C-46 Solar ContractorPhotovoltaic System InstallationEasy
A solar technician is installing a new PV array on a commercial flat roof. The design calls for a non-penetrating ballasted racking system. What is the primary method used to ensure the array's stability against wind uplift forces?
- AUsing aerodynamic deflector shields around the perimeter of the array.
- BDistributing concrete blocks or other heavy materials across the racking system.
- CApplying a specialized adhesive to bond the racking to the roof membrane.
- DAnchoring the racking system directly to the building's structural steel.
Show answer & explanationAnswer & explanation
Correct answer: B. Distributing concrete blocks or other heavy materials across the racking system.
Ballasted racking systems rely on the weight of distributed ballast (typically concrete blocks) to counteract wind uplift forces and hold the array in place without penetrating the roof membrane. This is their defining characteristic.
Why the other options are wrong
- A. Aerodynamic shields can help reduce wind loads but are not the primary method of resistance for a ballasted system; ballast provides the necessary weight.
- C. Adhesives are not the primary method for wind resistance in ballasted systems and may not be suitable for all roof membranes.
- D. This describes a penetrating racking system, not a ballasted one.
Ballasted Racking System
A non-penetrating PV mounting system that uses weight (ballast) to secure the array to the roof, resisting wind uplift.
- Avoids roof penetrations, reducing leak risk.
- Relies on distributed weight (e.g., concrete blocks) for stability.
- Requires careful load calculations to ensure roof structural integrity.
Memory trick: Heavy blocks on the roof, keeps the wind's strength aloof!