NABCEP Module Technology 2

Question 1

What is the primary cause of potential-induced degradation (PID) in crystalline silicon PV modules?

Accepted Answer

High voltage potential between cells and grounded frame causing ion migration

Answer

PID occurs when a high voltage difference between the cell circuit and the grounded module frame drives sodium ions through the glass, degrading the anti-reflective coating and cell junction.

Question 2

Which cell technology is most commonly used in bifacial PV modules to maximize rear-side light absorption?

Accepted Answer

PERC (Passivated Emitter and Rear Cell) cells

Answer

PERC cells use a dielectric passivation layer on the rear that reflects unabsorbed light back into the cell and allows rear-side bifacial generation, making them the dominant bifacial module technology.

Question 3

On a PV module datasheet, what does the temperature coefficient of Pmax (γ) indicate?

Accepted Answer

The percentage change in maximum power output per degree Celsius change in cell temperature

Answer

γ (gamma) is the temperature coefficient of Pmax, expressing how much the maximum power output changes (typically negative, e.g., -0.35%/°C) for each degree of cell temperature deviation from STC.

Question 4

What is 'light-induced degradation' (LID) and which cell type is most susceptible?

Accepted Answer

Initial power loss in the first hours of sunlight exposure, most common in boron-doped p-type crystalline silicon

Answer

LID is a reversible initial power loss (typically 1–3%) in boron-doped p-type c-Si cells caused by the formation of boron-oxygen defect complexes when first exposed to light.

Question 5

A module's bypass diode is rated for a forward current of 15 A. What is its primary purpose?

Accepted Answer

To provide a current path around shaded or damaged cells, limiting hot-spot heating

Answer

Bypass diodes conduct when cells in their protected group are reverse-biased due to shading or damage, preventing those cells from dissipating power as heat and becoming hot spots.

(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 2