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Solar PV System Design 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 Solar PV System Design flashcards as text

  1. A PV system designer is selecting between monocrystalline and polycrystalline modules for a space-constrained rooftop. Which module type is generally preferred and why?

    Answer: Monocrystalline, because it offers higher efficiency and greater power density per area

    Monocrystalline modules achieve higher efficiency (typically 19-23%) allowing more power to fit in a limited roof area despite their higher cost per module.

  2. What is the purpose of a rapid shutdown system (RSS) in a rooftop PV installation per NEC 690.12?

    Answer: To reduce PV system conductors to a safe voltage level within the array boundary for firefighter safety

    NEC 690.12 requires rapid shutdown to de-energize conductors within the array boundary to a safe voltage within 30 seconds, protecting firefighters from electric shock.

  3. When using microinverters instead of a string inverter, what key advantage is gained for systems with partial shading?

    Answer: Each module operates at its own maximum power point, minimizing shade impact on unshaded modules

    Microinverters perform MPPT at the individual module level, so shading on one module does not drag down the output of unshaded modules in the array.

  4. A designer is sizing conductors for a PV source circuit. The module Isc is 9.5A. Per NEC 690.8, what minimum ampacity must the conductors be rated for?

    Answer: 11.9A

    NEC 690.8(A) requires PV source circuit conductors to be rated for 125% of module Isc: 9.5A × 1.25 = 11.875A, rounded up to 11.9A minimum.

  5. In a battery energy storage system (BESS) paired with PV, what does 'depth of discharge' (DoD) refer to?

    Answer: The percentage of total battery capacity that is used before recharging

    Depth of discharge describes what fraction of total battery capacity is actually used; operating at lower DoD generally extends battery cycle life.

  6. Which production estimation method uses satellite-derived irradiance data and is commonly accepted in NABCEP best practices?

    Answer: TMY (Typical Meteorological Year) datasets used in software tools like PVWatts or SAM

    TMY datasets compiled from satellite and ground station data are the NABCEP-recognized standard for production estimation in tools like PVWatts and SAM.

  7. A grid-tied 10 kW AC system has an annual production of 13,500 kWh. What is its capacity factor?

    Answer: 15.4%

    Capacity factor = annual production / (rated power × 8,760 hours) = 13,500 / (10,000 × 8,760) × 100 ≈ 15.4%.