NABCEP Module Technology 4

Question 1

What is the significance of a module's maximum system voltage rating (e.g., 1000 V or 1500 V)?

Accepted Answer

It sets the maximum open-circuit voltage the module can withstand, limiting how many modules can be series-connected

Answer

The maximum system voltage rating defines the upper limit of open-circuit voltage the module's insulation and components can safely withstand, directly constraining the number of modules allowable in a series string.

Question 2

Which material is most commonly used as the transparent front cover of crystalline silicon PV modules, and why?

Accepted Answer

Tempered low-iron glass for its high transmittance, strength, and self-cleaning properties

Answer

Tempered low-iron glass is used because the reduced iron content maximizes optical transmittance (~91–93%), while tempering provides impact resistance and mechanical strength to meet IEC and UL standards.

Question 3

In a PV module's junction box, what is the role of the blocking diode (when installed)?

Accepted Answer

To prevent reverse current from flowing back through the module from a battery or parallel string

Answer

Blocking diodes prevent reverse current from flowing back into a module string when another string or battery source has a higher voltage, protecting against battery discharge through modules at night.

Question 4

What does IEC 61215 qualification testing primarily evaluate for crystalline silicon PV modules?

Accepted Answer

Long-term performance and durability under environmental stresses

Answer

IEC 61215 is the design qualification and type approval standard for c-Si modules, using accelerated stress tests (thermal cycling, damp heat, UV exposure, hail, mechanical load) to verify long-term reliability.

Question 5

How does an increase in cell temperature above 25°C affect the open-circuit voltage (Voc) of a crystalline silicon module?

Accepted Answer

Voc decreases approximately 0.3–0.4% per °C due to increased thermally generated carriers

Answer

In c-Si cells, Voc decreases with rising temperature (typically -2 to -2.3 mV/°C per cell, or about -0.3%/°C at module level) because thermal energy reduces the built-in junction voltage.

(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 4