NABCEP Module Technology 5

Question 1

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

Accepted Answer

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

Answer

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.

Question 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?

Accepted Answer

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

Answer

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.

Question 3

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

Accepted Answer

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

Answer

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.

Question 4

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

Accepted Answer

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

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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.

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

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

NABCEP Module Technology 5