CSLB C-46 Solar ContractorPlanning and EstimatingMedium
A C-46 contractor is evaluating different mounting solutions for a flat commercial roof that has limited structural capacity. The client is concerned about potential roof membrane penetrations and wants to minimize additional weight. Which racking system type would be most suitable for this scenario?
- APenetrating rail-based system.
- BElevated carport structure.
- CBallasted racking system.
- DIntegrated PV roof shingles.
Show answer & explanationAnswer & explanation
Correct answer: C. Ballasted racking system.
Ballasted racking systems are ideal for flat roofs with limited structural capacity and a desire to avoid penetrations. They use weight (ballast blocks) to secure the array, distributing the load over a larger area and eliminating the need for roof penetrations, which protects the roof membrane.
Why the other options are wrong
- A. Penetrating systems create holes in the roof, which the client wants to avoid, and may concentrate loads more than desired for limited structural capacity.
- B. Carport structures are ground-mounted or elevated and are not a solution for rooftop installations.
- D. Integrated PV roof shingles are typically for pitched roofs and involve replacing roof material, not suitable for a flat commercial roof with limited structural capacity.
Flat Roof Racking Systems
Methods and components used to secure solar PV modules on flat commercial or residential rooftops.
- Ballasted systems use weight to avoid penetrations.
- Mechanically attached systems penetrate the roof membrane.
- Considerations include wind uplift, structural capacity, and roof membrane integrity.
Memory trick: Flat Roofs Need Ballast or Penetrations.