Practice Test Geeks(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test
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System Maintenance & 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 System Maintenance & Troubleshooting flashcards as text

  1. A string inverter fails to start in the morning even though there is sufficient irradiance. The inverter display shows 'DC Voltage Too Low.' The MOST likely cause is:

    Answer: One or more modules are shaded or disconnected, reducing string Voc below the inverter's minimum start voltage

    If string Voc falls below the inverter's minimum operating voltage—due to shading, a disconnected module, or wiring fault—the inverter will not start until the voltage threshold is met.

  2. During maintenance of a rooftop PV system, a technician identifies roof penetrations that show signs of moisture ingress around the flashing. The MOST appropriate action is to:

    Answer: Refer the issue to a licensed roofing contractor and notify the system owner immediately

    Roof penetration leaks involve the building envelope and must be assessed and repaired by a licensed roofing contractor; improper DIY repairs can void roof warranties and worsen damage.

  3. A performance ratio (PR) calculation for a grid-tied system over a quarter comes out significantly lower than the design estimate. After confirming the monitoring data is accurate, which of the following is the LEAST likely cause?

    Answer: The AC utility voltage being within normal operating range

    Normal utility voltage within operating range does not significantly affect performance ratio; clipping, soiling, and irradiance data errors are all direct contributors to low PR.

  4. A technician is troubleshooting an off-grid inverter/charger that shows the battery voltage is normal but the inverter output is 0V AC. With the AC loads disconnected and a known-good battery, the MOST likely fault is:

    Answer: The inverter's internal transfer switch, output fuse, or power stage has failed

    If battery voltage is normal and loads are disconnected but AC output is absent, the fault is internal to the inverter—most commonly a failed output fuse, transfer relay, or power electronics stage.

  5. Which NEC article provides the primary requirements for photovoltaic system wiring methods, equipment, and installation?

    Answer: NEC Article 690

    NEC Article 690 specifically governs PV system installation requirements including wiring methods, overcurrent protection, grounding, and disconnecting means.

  6. When using a clamp meter to measure DC current in a PV string combiner, the technician must ensure that:

    Answer: Only a single conductor (positive OR negative) of the string is inside the clamp jaw at one time

    Clamping both conductors of a DC circuit simultaneously produces equal and opposite magnetic fields that cancel each other out, yielding a zero reading; only one conductor may be in the jaw.

  7. A NABCEP-certified technician reviewing long-term performance data notices that a system's annual degradation rate is 1.8% per year, significantly exceeding the manufacturer's warranted 0.5%/year. The BEST course of action is to:

    Answer: Document the findings with supporting data and contact the module manufacturer to initiate a warranty claim

    Degradation significantly above the warranted rate is grounds for a manufacturer warranty claim; the technician's role is to document the evidence and initiate the claim process on the owner's behalf.