Commissioning and Troubleshooting Flashcards
7 cards from real NABCEP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Commissioning and Troubleshooting flashcards as text
During commissioning of a roof-mounted system, you discover the array is tilted 5° south instead of the designed 20°. What is the most appropriate action?
Answer: Recalculate annual energy yield impact and inform the customer before finalizing
A significant tilt deviation affects annual yield and must be documented, quantified, and disclosed to the customer before project acceptance.
What instrument is most appropriate for verifying a PV module's I-V curve during commissioning?
Answer: I-V curve tracer
An I-V curve tracer sweeps the module from Isc to Voc and captures the full current-voltage relationship for performance verification.
A technician notices the ground fault indicator light is illuminated on a string inverter. What is the safest immediate action?
Answer: Disconnect AC and DC, lock out/tag out, then locate the fault before re-energizing
A ground fault is a serious safety hazard requiring LOTO procedures before troubleshooting to prevent arc flash or shock.
During insulation resistance testing of PV wiring with a megohmmeter at 500V DC, a reading of 0.5 MΩ is obtained. How should this be interpreted?
Answer: Marginal — values typically should be ≥1 MΩ per IEC standards
IEC 62446 requires insulation resistance values typically ≥1 MΩ; a 0.5 MΩ reading indicates degraded wiring insulation requiring further investigation.
A microinverter system shows one unit continuously reporting zero output in the monitoring portal while all neighboring units operate normally. What is the most likely cause?
Answer: The specific microinverter or its associated module has failed
A single non-reporting microinverter in an otherwise functioning system most likely indicates a failed microinverter or a defective module connected to it.
What is the primary purpose of performing a continuity test on PV array grounding conductors during commissioning?
Answer: To confirm a low-impedance path exists from array components to the grounding electrode
Continuity testing verifies that all metallic array components are bonded together and connected to the grounding system to provide effective fault current clearing.
After commissioning a battery storage system, the battery management system (BMS) shows a state of charge (SOC) that differs from the inverter's SOC display. What should a technician do?
Answer: Check commissioning documentation to determine which device is the SOC master and configure accordingly
Dual SOC readings indicate improper system integration; commissioning documentation specifies which device controls SOC and how the inverter should receive that data.