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

  1. Which test instrument is specifically used to verify that module-level power electronics (MLPEs) such as microinverters or DC optimizers are communicating and functioning correctly?

    Answer: The manufacturer's monitoring platform or gateway diagnostic interface

    MLPE manufacturers provide monitoring gateways or software platforms that communicate with each device and report individual unit status, error codes, and production data.

  2. During maintenance of a string inverter system, the technician measures a significantly higher DC input voltage than expected based on current irradiance and temperature. What is the most likely explanation?

    Answer: Modules have become cooler than the STC reference temperature, raising Voc

    PV module voltage increases as temperature decreases below STC (25°C), so on a cold day the open-circuit or operating voltage can significantly exceed the STC Voc rating.

  3. What is the correct procedure for safely working on a transformerless string inverter's DC side during maintenance?

    Answer: Open the AC disconnect first, then open the DC disconnect, and verify zero voltage with a meter before touching terminals

    The correct lockout/tagout sequence for a PV inverter is to open the AC side first (removing the load), then open the DC disconnect, and always verify zero energy with a calibrated meter before touching any terminals.

  4. A battery charge controller's absorption voltage setpoint has drifted above the battery manufacturer's recommended maximum. What is the most likely consequence if not corrected?

    Answer: Excessive gassing and electrolyte loss in flooded lead-acid batteries, or venting in sealed batteries

    Charging above the manufacturer's maximum voltage causes excessive electrolysis, accelerated water loss in flooded batteries, or pressure venting and damage in sealed VRLA batteries.

  5. When inspecting a rooftop PV array's penetration flashing and sealants, what is the primary maintenance concern?

    Answer: Checking for cracks, gaps, or deterioration that could allow water infiltration

    Roof penetrations are a primary source of water leaks; sealants degrade over time from UV exposure and thermal cycling, and any gaps must be repaired to prevent costly water damage.

  6. A monitoring system reports that one microinverter on a rooftop array has shown zero production for three consecutive days while neighboring units are operating normally. What is the LEAST appropriate first step?

    Answer: Immediately replace the microinverter without further diagnosis

    Replacing a microinverter without first diagnosing the cause wastes resources; the fault could be a loose connector, communication issue, or shaded/failed module rather than a failed microinverter.

  7. What does a low 'performance ratio' (PR) value in a grid-tied PV system's monitoring data most broadly indicate?

    Answer: The system is underperforming relative to its expected output given the available irradiance

    Performance Ratio (PR) is the ratio of actual energy output to the theoretical energy output calculated from irradiance, and a low PR indicates losses from soiling, shading, degradation, clipping, or equipment faults.