CHAPTER TWO THE PHOTOVOLTAIC EFFECT 2e A G.I. Module Energie Solaire Copyright, 2006 © Ahmed S. Bouazzi المدرسة الوطنية للمهندسين بتونس
The Photovoltaic Effect (1) The p-n Junction
E c E v E f Electrons current Holes current The photocurrent under illumination PHOTOVOLTAIC EFFFECT (2)
The Photovoltaic Effect (3) The photovoltage under illumination
I-V Characteristic of a p-n junction J (A/cm 2 ) V (mV) -J-J L Illumination Dark
Voltage (V) V co J sc Current (A/cm 2 ) (J,V) I-V Characteristic of a PV Generator The slope is 1/R
Hole density in the n side: Electron density in the p side: Minority Carrier Concentration = 0
G ( x, ) = ( ) ( ) exp { - ( ) x } ( ): flux of the incident light The Generation Function wavelength of the light ( ):absorption coefficient
Holes current (n side): Electrons current (p side): Photocurrent
p n d d+w l x h 0 n= 0 p= 0 Boundary Conditions
Holes current (n side): Electrons current (p side): Pseudo-neutral Regions Photocurrent Derivation
J w = q o { exp (- d) - exp [- (d+w)]} = q o exp (- d)[1 - exp (- w)] Depletion Region Photocurrent
Absorption Coefficient
n-side Photocurrent
p-side Photocurrent
For a given wavelength Quantum Response
The Effect of the Surface Recombination Velocity
The Effect of the Junction Depth
The Solar Spectrum
The total photocurrent: The Total Solar Current
I-V Characteristic of the PV Generator
Maximum Voltage
Maximum Photocurrent
Open Circuit Voltage
The Fill Factor
The Efficiency
The Output Power
The Ideal Equivalent Circuit
The Real Equivalent Circuit
The Real Circuit Equation
The Fill Factor
The Series Resistance Effect
The Shunt Resistance Effect
The Cell Temperature Effect