ET3034TUx Solar Energy
posted by Anon on .
The current density of an ideal pn junction under illumination can be described by:
J(V)=Jph−J0(eqVkT−1)
where Jph is the photocurrent density, J0 the saturationcurrent density, q the elementary charge, V the voltage, k the Boltzmann's constant, and T the temperature.
A crystalline silicon solar cell generates a photocurrent density of Jph=40mA/cm2 at T=300K. The saturationcurrent density is J0=1.95∗10−10mA/cm2.
Assuming that the solar cell behaves as an ideal pn junction, calculate the opencircuit voltage Voc (in V).

0.674

J0=1.95∗10−10mA/cm2=1.95*10^9A/m^2
Jph=40mA/cm2=400A/m^2
Voc=kT/q*ln(Jph/J0+1)
T=300K
k=1.35*10^23J/K
q=1.6*10^19C
J(V)=Jph−J0(eqVkT−1)
The opencircuit voltage is the voltage at which the net current is zero where J(Voc)=0
Solving for Voc we have
Voc=0.0253*ln((400+1.95*10^9)/(1.95*10^9))
Voc=0.659 V