NABCEP Solar PV Fundamentals 4

Question 1

What is the theoretical maximum efficiency limit for a single-junction silicon PV cell under unconcentrated sunlight, known as the Shockley-Queisser limit?

Accepted Answer

Around 29–33%

Answer

The Shockley-Queisser limit for a single p-n junction under AM1.5 illumination is approximately 29–33%, due to thermalization and transmission losses.

Question 2

What does NOCT stand for and how is it used in PV module performance estimation?

Accepted Answer

Normal Operating Cell Temperature — used to estimate cell temperature under realistic outdoor conditions

Answer

NOCT is the cell temperature at 800 W/m², 20°C ambient, and 1 m/s wind; it is used to estimate real-world operating temperatures.

Question 3

What happens to minority carrier lifetime when a silicon solar cell has higher impurity or defect concentrations?

Accepted Answer

Minority carrier lifetime decreases, increasing recombination and reducing efficiency

Answer

Defects and impurities create recombination centers that reduce minority carrier lifetime, lowering open-circuit voltage and efficiency.

Question 4

Which type of charge carrier moves from the p-type to n-type layer across the depletion region in an illuminated p-n junction solar cell?

Accepted Answer

Photo-generated electrons are swept from p-type to n-type by the built-in electric field

Answer

The built-in electric field at the depletion region sweeps photo-generated minority electrons from the p-side to the n-side, generating current.

Question 5

When comparing bifacial PV modules to monofacial modules, what is the primary performance advantage of bifacial modules?

Accepted Answer

Additional energy generation from reflected or diffuse light hitting the rear surface

Answer

Bifacial modules generate additional power from albedo (reflected) light incident on the rear cell surface, boosting total energy yield.

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

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

NABCEP Solar PV Fundamentals 4