Module Technology Flashcards

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

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

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.

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

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

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.

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

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

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.

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

Answer: Long-term performance and durability under environmental stresses

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.

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

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

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.

What is the purpose of anti-reflective coating (ARC) on silicon PV cells?

Answer: To reduce light reflection from the silicon surface and increase the amount of light absorbed by the cell

Silicon's refractive index causes it to reflect about 35% of incident light without ARC; the typically silicon nitride (Si₃N₄) coating uses destructive interference to reduce reflection to under 4%, boosting efficiency.

A PV module has a power tolerance of +5%/-0%. What does this specification mean for system design?

Answer: The module's actual STC power output will be at or above its nameplate rating, never below

A +5%/-0% tolerance means the manufacturer guarantees the module will deliver at least its rated power at STC, with possible upside of up to 5% more, eliminating the risk of underperforming nameplate ratings.