NABCEP NABCEP PV Commissioning and Maintenance Specialist 1 — Questions and Answers
Question 1: What is the primary purpose of a commissioning inspection for a newly installed PV system?
- To verify the system operates safely and as designed before handover (Correct answer)
- To determine the system's aesthetic appearance
- To calculate the system's payback period
- To register the system with the utility
Correct answer: To verify the system operates safely and as designed before handover
Commissioning verifies that all components are installed correctly and the system operates safely and per design specifications before being handed over to the owner.
Question 2: During a PV system commissioning, what is the correct sequence for energizing the system?
- AC side first, then DC side
- DC side first, then AC side (Correct answer)
- Both sides simultaneously
- It does not matter which side is energized first
Correct answer: DC side first, then AC side
The DC side is energized first during commissioning so that the inverter can be safely started up after confirming DC voltage and polarity.
Question 3: Which tool is essential for verifying PV string open-circuit voltage during commissioning?
- Clamp meter
- Digital multimeter (Correct answer)
- Power analyzer
- Pyranometer
Correct answer: Digital multimeter
A digital multimeter measures open-circuit voltage (Voc) of PV strings to confirm they are within expected ranges before connection.
Question 4: What does an insulation resistance test (megohm test) during commissioning detect?
- Inverter efficiency
- Ground faults or damaged insulation in wiring (Correct answer)
- Module power output degradation
- Battery state of charge
Correct answer: Ground faults or damaged insulation in wiring
A megohm test applies high voltage to conductors to detect insulation breakdowns or ground faults that could cause safety hazards.
Question 5: A PV system's string current reads significantly lower than expected during commissioning. What is the most likely cause?
- High ambient temperature
- A shaded or failed module in the string (Correct answer)
- Inverter over-frequency trip
- Utility voltage fluctuation
Correct answer: A shaded or failed module in the string
A shaded or failed module creates a bottleneck that reduces the entire string's current output below expected levels.
Question 6: Which document should a commissioning technician provide to the system owner at project closeout?
- Manufacturer's raw component cost list
- As-built drawings, system manual, and commissioning report (Correct answer)
- Utility interconnection application only
- Permit application forms
Correct answer: As-built drawings, system manual, and commissioning report
As-built drawings, the system manual, and a commissioning report give the owner accurate documentation for operation, maintenance, and future service.
NABCEP NABCEP PV Commissioning and Maintenance Specialist 1
What is the primary purpose of a commissioning inspection for a newly installed PV system?