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Module Technology 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 Module Technology flashcards as text

  1. What is the difference between a module's 'nameplate efficiency' and its 'aperture efficiency'?

    Answer: Nameplate efficiency is based on total module area including frame, while aperture efficiency uses only the active cell area

    Nameplate (module) efficiency divides Pmax by total module area including frame, while aperture efficiency uses only the light-collecting cell area, making aperture efficiency always higher than nameplate efficiency.

  2. Which phenomenon causes a string of modules to produce less current than a single unshaded module when one module in the string is partially shaded?

    Answer: Series circuit current is limited to the lowest current module in the string, so partial shading of one module reduces current for all

    In a series string, current must be the same through all modules; the most shaded module limits string current to its reduced Isc, causing disproportionate power loss across the entire string.

  3. What is the primary advantage of half-cut cell module technology compared to standard full-cell modules?

    Answer: Splitting cells in half reduces resistive (I²R) losses and minimizes the power loss from partial shading of one cell row

    Half-cut cells carry half the current of full cells, reducing I²R losses by 75% in each cell (loss ∝ I²), and the module is internally split into two independent half-modules that reduce partial shade impact.

  4. For a grid-tied PV system in the US, which standard governs the electrical safety requirements that PV modules must meet?

    Answer: UL 61730 (formerly UL 1703) — Safety Standard for Photovoltaic Modules

    UL 61730 (harmonized with IEC 61730) is the US safety standard covering module construction, insulation, fire resistance class, and electrical safety required for NEC-compliant grid-tied installations.

  5. What is 'snail trail' degradation in PV modules, and what causes it?

    Answer: Brown discoloration patterns on module glass caused by silver paste oxidation through micro-cracks in cells

    Snail trails are brownish discoloration lines on the module glass that follow micro-cracks in cells; moisture penetrates cracks and oxidizes the silver cell metallization, causing visible marks and potential power loss.

  6. How does irradiance level affect the short-circuit current (Isc) and open-circuit voltage (Voc) of a PV module differently?

    Answer: Isc changes proportionally with irradiance; Voc changes logarithmically and much less

    Isc is directly proportional to irradiance (halve the sun, halve the current), while Voc changes only logarithmically — dropping roughly 5–10% at half irradiance versus 50% for Isc.

  7. A module's backsheet is rated as 'Type A' per IEC 61730. What does this fire performance classification require?

    Answer: The module must pass Class A fire spread tests equivalent to roofing material requirements, representing the highest fire resistance level

    IEC 61730 Application Class A (fire rating) requires the module to meet the most stringent fire resistance criteria, equivalent to UL Class A roofing — required for residential rooftop installations in most US jurisdictions.