NABCEP PV System Mechanical Installation 3 — Questions and Answers
Question 1: What wind exposure category would typically apply to a PV array installed on a building located in an open terrain with scattered obstructions?
- Exposure A
- Exposure B
- Exposure C (Correct answer)
- Exposure D
Correct answer: Exposure C
Exposure C applies to open terrain with scattered obstructions generally less than 30 feet high, which increases wind pressure on structures.
Question 2: When calculating roof dead load capacity for a PV installation, what is a typical weight range for crystalline silicon PV modules?
- 1–2 psf
- 2.5–4 psf (Correct answer)
- 5–8 psf
- 8–12 psf
Correct answer: 2.5–4 psf
Most standard crystalline silicon modules weigh between 2.5 and 4 pounds per square foot including the racking system.
Question 3: Which of the following describes the correct sequence for installing a ballasted flat-roof racking system?
- Place ballast, install rails, attach modules, verify tilt angle
- Install rails, attach modules, place ballast, verify tilt angle
- Verify tilt angle, install rails, attach modules, place ballast (Correct answer)
- Install rails, verify tilt angle, place ballast, attach modules
Correct answer: Verify tilt angle, install rails, attach modules, place ballast
Tilt angle must be verified first, then rails installed, ballast added to hold the system, and finally modules attached and secured.
Question 4: What is the primary reason for maintaining a minimum clearance between the bottom of PV modules and the roof surface?
- To allow electrical conduit routing underneath
- To facilitate airflow for module cooling and debris removal (Correct answer)
- To meet fire setback requirements only
- To allow rainwater collection
Correct answer: To facilitate airflow for module cooling and debris removal
Adequate clearance promotes airflow under modules to dissipate heat, improving performance, and allows debris and water to clear.
Question 5: A 2×6 rafter is being assessed for additional loading from a rooftop PV array. Which document governs the structural capacity of wood framing members?
- NEC Article 690
- IBC and AWC NDS (National Design Specification) (Correct answer)
- NFPA 72
- ASCE 7 Chapter 12
Correct answer: IBC and AWC NDS (National Design Specification)
The International Building Code (IBC) combined with the AWC National Design Specification governs the structural design of wood framing members.
Question 6: Which type of roof attachment is most suitable for a tile roof to avoid breaking tiles during PV installation?
- Direct lag into tile
- Tile replacement mount or tile hook (Correct answer)
- Rail-less adhesive system
- Through-tile concrete anchor
Correct answer: Tile replacement mount or tile hook
Tile replacement mounts or tile hooks are designed to integrate with the tile profile, eliminating the need to drill through fragile tiles.
Question 7: In a BIPV (building-integrated PV) installation, modules serve as which building component?
- Structural columns
- Roofing or cladding material replacing conventional building materials (Correct answer)
- Electrical conduit pathways
- Thermal insulation layer
Correct answer: Roofing or cladding material replacing conventional building materials
BIPV modules replace conventional roofing, glazing, or cladding while simultaneously generating electricity.
NABCEP PV System Mechanical Installation 3
What wind exposure category would typically apply to a PV array installed on a building located in an open terrain with scattered obstructions?