Practice Test Geeks(NABCEP) Certified North American Board of Certified Energy Practitioners Specialist Practice Test
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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

  1. A battery-based PV system frequently reaches 100% SOC early in the day and then diverts excess power, but the customer reports nightly power outages. What should the technician evaluate?

    Answer: Verify battery capacity is sufficient for the nightly load and that SOC calibration is accurate

    Early charge completion with nightly outages suggests either battery capacity is undersized for the load or the SOC sensor is inaccurately reading 100% before the bank is truly full.

  2. During commissioning, a technician measures 240 VAC between L1 and L2 at the inverter output but 0 VAC between L1 and neutral. What does this indicate?

    Answer: The neutral conductor is open or disconnected

    Correct 240V L1-L2 with 0V L1-N indicates the neutral conductor is interrupted, creating a floating neutral condition that can damage 120V loads.

  3. What is the purpose of a 'string health check' report generated by a modern monitoring platform?

    Answer: It compares actual string energy output to expected output to identify underperforming strings

    String health reports use performance ratio algorithms to compare measured vs. expected output, flagging strings that are underperforming relative to modeled predictions.

  4. A newly commissioned PV system passes all DC electrical tests but the inverter immediately faults on 'AC Frequency Out of Range.' What is the likely cause?

    Answer: The inverter's grid frequency parameter has been configured incorrectly for the US 60 Hz grid

    Inverters configured for 50 Hz markets will fault immediately when connected to the US 60 Hz grid; commissioning must verify all grid parameters match local utility specifications.

  5. During troubleshooting, a technician suspects a failed bypass diode in a module. Which test method can confirm this without removing the module?

    Answer: Use a clamp meter on each substring under load to check for anomalously low current through bypass diode paths

    A shorted bypass diode creates an alternative current path; measuring current distribution with a clamp meter under load can reveal abnormal conduction through diode circuits.

  6. Why is it important to verify the arc-fault circuit interrupter (AFCI) function during PV system commissioning?

    Answer: NEC 690.11 requires AFCI protection on DC circuits, and its correct operation must be verified before system acceptance

    NEC 690.11 mandates AFCI protection on PV DC circuits operating above 80V; commissioning must confirm the device activates correctly to prevent fire from arcing faults.

  7. A customer reports that their grid-tied PV system export to the grid has dropped by 30% over 6 months with no obvious equipment faults. What systemic issue should the technician investigate?

    Answer: Progressive soiling, shading from vegetation growth, or module degradation affecting energy yield

    Gradual export reduction over months commonly results from accumulating soiling, new shading sources such as tree growth, or accelerated module degradation.