PN junctions and diodes

Which is the correct definition of the fill factor (FF) of a solar cell?

  1. AShort-circuit current ÷ open-circuit voltage
  2. BOutput power ÷ incident light energy
  3. CMaximum power ÷ (open-circuit voltage × short-circuit current)
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Answer: C. Maximum power ÷ (open-circuit voltage × short-circuit current)

The fill factor is the power at the maximum power point divided by the product of the open-circuit voltage and short-circuit current. It indicates how close the current-voltage curve is to a rectangle, and it decreases with losses such as a large series resistance. Conversion efficiency is the maximum power divided by the incident light power.

  • A. Current divided by voltage is not the fill factor.
  • B. Output power divided by incident light power is the conversion efficiency.
  • C. Correct. FF = Pmax / (Voc × Isc).
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More PN junctions and diodes questions

  1. Roughly what is the small-signal (dynamic) resistance of an ideal silicon diode carrying a forward current of 1 mA at room temperature? (kT/q ≈ 26 mV)
  2. How does the breakdown voltage of a PN junction generally change when the impurity concentration on one side is lowered?
  3. What is the main role of ESD protection diodes connected to the input/output pins of an IC?
  4. Zener diodes with a Zener voltage of about 5 to 6 V show little change in voltage with temperature. Why?
  5. What is a common way to make a metal-semiconductor contact ohmic (resistive)?