Practice Test Geeks(NABCEP) North American Board of Certified Energy Practitioners Solar Practice Test
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Commissioning 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 flashcards as text

  1. What is the correct sequence for de-energizing a grid-tied PV system during a commissioning fault investigation?

    Answer: Open AC disconnect first, then DC disconnects from array

    The inverter AC disconnect is opened first to stop current flow, then DC disconnects are opened to safely de-energize the array side.

  2. A newly commissioned microinverter system shows that one microinverter is offline in the monitoring portal. Which commissioning step would identify this before system handover?

    Answer: Comparison of expected vs. actual microinverter count in the monitoring system

    Commissioning should include verifying that every installed microinverter is communicating and visible in the monitoring platform before owner handover.

  3. During commissioning, a string of 10 modules measures 385 V Voc instead of the expected 410 V. Which condition would most likely explain this discrepancy without indicating a fault?

    Answer: Ambient temperature is 35°C instead of the STC 25°C

    Higher ambient temperatures reduce Voc; at 35°C the array voltage will be lower than the STC (25°C) nameplate calculation.

  4. Which document must the installer obtain from the utility before energizing the point of common coupling (PCC) on a grid-tied system?

    Answer: Utility permission to operate (PTO) or interconnection approval

    Utility permission to operate (PTO) is required before the system can export power to the grid; energizing without it violates the interconnection agreement.

  5. What is the primary purpose of measuring the short-circuit current (Isc) of each source circuit at the combiner during commissioning?

    Answer: To verify each string is producing and confirm no open-circuit failures

    Measuring Isc at the combiner confirms each string is producing current and helps identify strings with failed modules, bad connections, or incorrect wiring.

  6. A commissioning report for a ground-mount system requires documenting the system grounding electrode. Which electrode type is specifically permitted for PV systems under NEC 690?

    Answer: Any grounding electrode permitted under NEC Article 250

    NEC 690.47 requires PV system grounding electrodes to comply with Article 250 Part III, using any grounding electrode type permitted therein.

  7. During owner training at system handover, which monitoring metric should the installer specifically explain to help the owner detect system underperformance early?

    Answer: Specific yield (kWh/kWp) compared to historical local irradiance

    Specific yield normalizes production by system size and allows the owner to compare output against expected values based on local solar resource data.