Department of Electrical & Electronic Engineering
ORT Braude College
Advanced Laboratory for Characterization of Semiconductor Devices - 31820
Solar Cell
(photovoltaic cell)
March 23, 2016
Dr. Radu Florescu
Dr. Vladislav Shteeman
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
The goal.
In this experiment, you will measure the Current-Voltage (I-V) characteristics of a
photovoltaic cells’ module and extract its main physical parameters using computerized
parameter analyzer Keithley SCS 4200.
The following characteristics will be extracted from the I-V measurements:
1. Dark I-V characteristics
1.1. Shunt resistance Rshunt
1.2. Ideality factor n and saturation current I sat
1.3. Series resistance Rseries
2. Illuminated I-V characteristics
2.1. Maximum power point Pmax .
2.2. Maximum Power Voltage and Current values Vmax
and I max
such as
Pmax  I maxVmax .
2.3. Cell efficiency  
Pmax
Pin
where Pin is the power of the incoming light.
2.4. Open Circuit Voltage VOC (output current I  0 ).
2.5. Short Circuit Current I SC (output voltage V  0 ).
2.6. Fill Factor FF  I maxVmax I SCVOC 
Dr. Radu Florescu
Dr. Vladislav Shteeman
2
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Short theoretical background.
Solar cell[1] (also called photovoltaic cell) is a specific kind of semiconductor diode, that
directly converts the energy of light into the electrical energy through photovoltaic effect
(see Figure 1).
Figure 1. Sketch of principle of operation of solar cell.
Typical I-V characteristics of a solar cell is shown on Figure 2.
Figure 2. Sketch of I-V characteristics of a solar cell (after [2]).
Dr. Radu Florescu
Dr. Vladislav Shteeman
3
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Today, the majority of solar cells are fabricated from silicon. Unlike batteries or fuel cells,
solar cells do not utilize chemical reactions or require fuel to produce electric power, and,
unlike electric generators, they do not have any moving parts.
Equivalent circuit of solar cell is shown on Figure 3:
Figure 3. Equivalent circuit of solar cell (after [2]).
In solar cell, there are 2 parasitic resistances: series resistance Rseries and shunt resistance
Rshunt , which impact the performances of photovoltaic device (see Figure 3 and List of
definitions in Appendix 3 for definitions of Rseries and Rshunt ). Ideally, series resistance should
be zero ( Rseries  0 ), while shunt resistance should be infinite ( Rshunt   ).
1. Model of solar cell I-V characteristics [2],[3].
At the 1st approximation, I-V characteristics of solar cell (being a specific kind of diode),
measured in the dark, can be described by the modified Shockley equation, corrected for
series resistance Rseries .
As opposite to a “standard” diode, Rseries affects I-V characteristics of solar cell all along, not
only for VD  V0 (where V0 is a built-in voltage). Rseries here is a model, representing (arising
from) the combination of three majors resistances:
Dr. Radu Florescu
Dr. Vladislav Shteeman
4
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
1) the intrinsic silicon resistance
2) the contact resistance between the metal contact and the doped silicon regions
3) the resistance of the top and the rear metal contacts
Thus,
 VD kTI D Rqseries  
I D  I dark   I satdark   e
 1





dark
(1)
current
(where I D ,VD - measured current and applied voltage, I dark - current measured in the dark,
I satdark  - saturation current of ideal pn-junction (from Shockley modes), q - electron charge,
k - Boltzmann constant, T K  - temperature)
At the 2nd approximation, due to the large surface and the complex association of non-ideal
materials, generation-recombination current in the depletion layer should be accounted for:
 VD kTI D Rqseries  
 VD 2IkTD Rqseries  
I D  I dark   I rec   I satdark   e
 1  I satrec   e
 1





  


dark
current
recombination
(2)
current
( I satdark  - saturation current due to generation-recombination only)
The usual practice is to introduce an ideality factor, n , which allows to account for both
currents in a single expression:
I D R series 
 VD nkT

q

I D  I sat e
 1




Dr. Radu Florescu
Dr. Vladislav Shteeman
(3)
5
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
( I sat - saturation current due to both generation-recombination current and “dark” current)
At the 3rd approximation, one should account for influence of shunt (parallel) resistance,
Rshunt . Presence of Rshunt may cause significant power losses in a solar cell. Those losses are
typically due to the manufacturing defects, rather than because of poor solar cell design. Low
Rshunt causes power losses by providing an alternate current path for the light-generated
current. This reduces the current, flowing through the solar cell pn-junction and reduces the
voltage, acquired from the solar cell.
The influence of Rshunt is particularly strong at low light intensities, since there will be less
light-generated current. In addition, at lower voltages where the effective resistance of a
solar cell is high, the impact of a resistance in parallel is large.
Thus, accounting for Rshunt gives:
I D R series 
 VD nkT

VD  I D Rseries
q
ID 
 I sat  e
 1


Rshunt


(4)
At the 4th approximation, under illumination conditions, the additional current, I light , is
generated by the electron-hole photoemission. Thus, the total current via the photovoltaic
cell will have a form:
V D  I D Rseries 


V I R
I D  D D series  I sat  e nkT q  1  I light



Rshunt

 light current
(5)
different currents in the dark
Dr. Radu Florescu
Dr. Vladislav Shteeman
6
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
2. Evaluation of different physical parameters of solar cell from
the I-V measurements.
2.1.
Evaluation of I max , Vmax , I SC , VOC , Pmax , FF (see List of symbols in Appendix 1 for
details).
All the physical parameters above can be estimated from I-V characteristics of forward biased
solar cell (see
Figure 4 for details).
Figure 4. Typical forward bias I-V characteristics of a solar cell (after [2]).
2.2.
Evaluation of the shunt resistance Rshunt .
Rshunt can be derived from the graph of reverse-bias I-V measurements (in range from 0 to
~  1  2 V ) (see Figure 5). The test must be performed in the dark.
Dr. Radu Florescu
Dr. Vladislav Shteeman
7
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Figure 5. Explanation to calculation of Rshunt of solar cell (after [2]).
Rshunt can be calculated from the linear fit of the I-V graph:
Rshunt 
1
slope
(6)
The expected value of Rshunt in this experiment is ~ 400 .
2.3.
Evaluation of series resistance Rseries .
We’ll estimate series resistance Rseries using so-called Slope method. This method is based on
the measurements of I –V characteristics of the cell at two different light intensities giving
the short-circuit currents I SC (1) and I SC ( 2 ) , respectively (see Figure 6).
I SC (1)
I SC ( 2 )
Rseries 
V V(1)  V( 2 )

I
I ( 2 )  I (1)
Figure 6. Explanation to the series resistance measurement by the Slope method (after [2]).
Dr. Radu Florescu
Dr. Vladislav Shteeman
8
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
The current  I below the I SC , I  I SC   I , is picked on both I–V curves. The currents
I (1)  I SC (1)   I and I ( 2 )  I SC ( 2 )   I correspond to the voltages V(1) and V( 2 ) . The series
resistance is then:
Rseries 
V(1)  V( 2 )
V V(1)  V( 2 )
1



I
I ( 2 )  I (1) I SC ( 2 )  I SC (1) slope
(7)
By using more than two light intensities, more than two points are generated. Drawing a line
through all of the points gives the series resistance by the slope of this line (see
Figure 7).
Figure 7. Example of series resistance measurements by the Slope method (after [2]).
The expected value of Rseries in this experiment is ~ 0.8  1.2  .
2.4.
Evaluation of dark saturation current I 0 and ideality factor n .
Knowledge of Rseries allows one to estimate (from the dark measurements) the dark
saturation current I sat and ideality factor n . As it follows from the Eq. (3), in the middle
and high voltage regions VD  0.15 V  ,
I D  I sate
V D  I D R series
kT
n
q
Dr. Radu Florescu
 I sate
V D  I D R series
0.027n
Dr. Vladislav Shteeman
(8)
9
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Making exponential fit (adding exponential trend line) to the I-V curve in the middle
region of voltages (say, 0.2  V  0.35 ) allow us to get 2 parameters of the fitting curve,
fit
namely, the amplitude I sat
and the power  of the exponential function:
fit  V D
I Dfit  I sat
e
(9)
Comparing Eq. (8) with Eq. (9) we find, that for each pair of values I-V in the range
0.2  V  0.35 holds:
fit
I sat  I sat
, VD 
VD  I D Rseries
0.027n
(10)
fit
Thus, fitting parameter I sat
directly gives us the dark saturation current I sat . In addition,
from Eq. (10):
n
1  VD  I D Rseries 


VD  0.027 
(11)
Computation of ideality factor n for all the pairs of I-V values in the range
0.2  VD  0.35 (according to Eq. (11)) yields a set of (experimental) factors n , which
are slightly different from each other. The average of this set gives an estimation of the
(theoretical) ideality factor n , appearing in Eq. (8).
Dr. Radu Florescu
Dr. Vladislav Shteeman
10
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Assignments and analysis
Preparation of the experimental setup
1. Check (and change if necessary) the cables connections on the rare panel of the
switching matrix and S4200 analyzer (see
Dr. Radu Florescu
Dr. Vladislav Shteeman
11
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
2. Appendix
2 for details about the cables connection).
3. Using “crocodiles”, connect (via the four manipulators) the “+” contact of the solar
cell to the 1st and 2nd cables and the “-” contact to the 3rd and 4th cables. Place the
cell on the chunk table in the Shielded probe station.
4. Measure the area of the solar cell.
I-V characteristics measurements
Note: Before executing the measurements and processing the acquired data, save this data solar cell
processing (empty).xlsx
Excel template to the Desktop of the Keithley computer (double click on the Excel icon
 File
 Save as … ). During the measurements, fill in the data in the B - D columns of the
template.
After finishing the measurements, copy their results (located in the
measurements folder of Keithley in the subdirectory “tests/data”), namely, data from the
files “rev-ivsweep#1@4.xls” and “fwd-ivsweep#1@4.xls” to the Excel template.
Dark I-V characteristics
1. Open the Keithley Solar cell program. Manually connect pins (A1 – B2 – D3
– E4) using the switching matrix and the light pen (see Appendix 3).
2. Close the doors of the Shielded probe station and run the measurements of
the forward and backward biased I-V characteristics.
SAVE ALL THE RESULTS in the Keithley program.
Light I-V characteristics
Dr. Radu Florescu
Dr. Vladislav Shteeman
12
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
1. Switch on the Solar simulator lamp (using the lamp controller) in the
Shielded probe station. Use “set” button on the controller panel
(press and hold 2 seconds) and arrows buttons to set the power,
supplied to the lamp, to 80 W.
2. Wait for 5 minutes to let the lamp warm up.
light spot from
the lamp
3. Check if the light spot from the lamp fully covers the area of the
photovoltaic cell. If it is necessary – move the lamp upward or
downward to change the size of the spot.
4. Switch on the power meter and zero its meterage (press “zero” button
when the device’ detector is inside the Shielded probe station).
5. Measure the incident light power on the light spot, using the Power
meter. Write the measured value into the Excel table.
6. Run the Keithley measurement program and acquire I-V characteristics of the
photovoltaic cell for forward bias only. (PAY ATTANTION: Use the yellow-greed
button
(“append”) to run the measurement. DO NOT use the green button
(“override”): it overrides your previous measurements.)
SAVE ALL THE RESULTS in the Keithley program.
7. Use “set” button on the controller panel (press and hold 2 seconds) and arrows
buttons to set the power, supplied to the lamp, to 90 W and wait for 5 minutes.
Return to the steps 5-6 above.
8. Use “set” button on the controller panel (press and hold 2 seconds) and arrows
buttons to set the power, supplied to the lamp, to 100 W and wait for 5 minutes.
Return to the steps 5-6 above.
9. Cover the solar cell with the ND 2 filter. (This filter reduces the intensity of the light
by factor 2, see Appendix 5 for details.) Return to the steps 5-6 above.
10. Cover the solar cell with the ND 4 filter. (This filter reduces the intensity of the light
by factor 4, see Appendix 5 for details.) Repeat the steps 5-6 above.
Dr. Radu Florescu
Dr. Vladislav Shteeman
13
photovoltaic
cell
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
SAVE ALL THE RESULTS in the Keithley program.
Use Table 1 to convert the electrical power, supplied to the Solar emulator, into the
optical power (per unit area) of the outgoing light.
Evaluation of physical parameters from I-V measurements.
1. Shunt resistance Rshunt . From the dark I-V measurement at the reverse bias, evaluate
the shunt resistance Rshunt of the solar cell, as explained in the subsection “Evaluation of
the shunt resistance “ (see p. 7).
2. Series resistance Rseries . From the light I-V measurements at the forward bias,
evaluate the series resistance Rseries of the solar cell, as explained in the subsection
“Evaluation of series resistance “ (see p. 8).
3. Dark saturation current I 0
and ideality factor n . From the dark I-V
measurements at the forward bias in the middle region ( 0.2  V  0.35 ), evaluate the
dark saturation current I 0 and the ideality factor n , as explained in the subsection “
4. Evaluation of dark saturation current
I 0 and ideality factor n . “ (see p. 9).
5. Different physical parameters of the solar cell. For each of the I-V measurements
(both light and dark) at the forward bias, calculate I max , Vmax , I SC , VOC , Pmax , FF , as
explained in the subsection “Evaluation of I max , Vmax , I SC , VOC , Pmax , FF ” (see p. 7).
Fill in the following Table (in the Excel file):

Pin Watt / cm 2

I max A Vmax V 
I SC A VOC V 
Pmax Watt
Intensity 1
Intensity 2
Intensity 3
Intensity 4
Intensity 5
Dr. Radu Florescu
Dr. Vladislav Shteeman
14
FF 
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
(Here, Pin Watt is a multiplication of the incoming optical power per unit area (see
Table 1 in Appendix 4) and the area of the photovoltaic cell (4.25 cm2) ).
6. Present graphically the data, acquired in the Table above. Namely, build in Excel (and
include in the Final report) the following graphs:
a) I max vs Pin
b) Vmax vs Pin
c) I SC vs Pin
e) Pmax vs Pin
f) FF vs Pin
g)  vs Pin
Dr. Radu Florescu
Dr. Vladislav Shteeman
d) VOC vs Pin
15
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Final Report content.
Final Report must include the following solar cell’ parameters and
graphs with explanations:
[1] I-V characteristics of solar cell in the dark (2 graphs: I D VD  for forward and for reverse bias)
[2] A set of I-V characteristics of solar cell under different lightening intensities I D VD  (a single
graph)
[3] Shunt resistance Rshunt (a single value)
[4] Series resistance Rseries (a single value)
[5] Saturation current I sat (a single value)
[6] Ideality factor n (a single averaged value)
[7] A filled table:

Pin Watt / cm 2

I max A Vmax V 
I SC A VOC V 
Pmax Watt
Intensity 1
Intensity 2
Intensity 3
Intensity 4
Intensity 5
[8] The following graphs (2 graphs, including each 3-4 subplots):
a) I max vs Pin
b) Vmax vs Pin
c) I SC vs Pin
e) Pmax vs Pin
f) FF vs Pin
g)  vs Pin
Dr. Radu Florescu
Dr. Vladislav Shteeman
d) VOC vs Pin
16
FF 
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Experimental set-up and sample to be studied
The experimental setup includes

Keithley switching matrix and SCS 4200 I-V and Parameter analyzer (Figure 8)

Shielded probe station (SPS) with the Solar simulator lamp (Figure 9)

Photovoltaic cell (Figure 11)

Portable power meter (Figure 10)
Lamp controller
Lamp controller
Keithley 708A
Switching Matrix
Solar simulator lamp
Monitor
Photovoltaic cell
Keithley SCS 4200 I-V
AND Parameter analyzer
Figure 9. Shielded probe station (SPS) with
the Solar simulator lamp and controller.
Figure 8. Keithley measurement setup
Photovoltaic cell
area is 4.25 cm2
Figure 11. Photovoltaic cell.
Figure 10. Power meter
Dr. Radu Florescu
Dr. Vladislav Shteeman
17
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Acknowledgement
Electrical Engineering Department of Braude College would thank to Alex Cherchun for his
extensive help in the preparation of this laboratory work.
Several parts of this brochure were adapted from the Amorphous Silicon Solar Module
manual of the Advanced Semiconductor Devices Lab (83-435) of School of Engineering of BarIlan University. We would like to thank Dr. Abraham Chelly for the granted manual.
Dr. Radu Florescu
Dr. Vladislav Shteeman
18
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Appendix 1 : List of symbols and definitions
List of symbols





Rseries - series resistance 
Rshunt - shunt resistance 
Pmax - maximum power point W 
I D - current through the pn-junction A
I sat - a total saturation current, including

different currents in the dark A
I dark - dark current A

I satdark  - saturation dark current (saturation








current of ideal diode) A
I  rec  - generation-recombination current
in the depletion region A
I satrec  - saturation current of generation-recombination current A
I light - light current A
q  1.6  1019 - electron charge C 
n - ideality factor [dimensionless]
I SC - short circuit current (output voltage VD  0 ) A
VOC - open circuit voltage (output current I D  0 ) V 
VD - voltage (bias) applied to the diode (solar cell) V 
 V0 - Built-in voltage








I max - maximum power current (corresponding to the max. power point Pmax ) A
Vmax - maximum power voltage (corresponding to the max. power point Pmax ) V 
FF - fill factor: FF  I maxVmax I SCVOC  [dimensionless]. % of efficiency vs. an ideal cell.
A - pn-junction’ cross-section area cm2 
kT - thermal energy (i.e. energy, associated with the temperature of the object, T )
kT
- thermal voltage V . For the room temperature: T  300  K  kT q  0.026 V 
q
Pin incoming light’ power W . Can be computed as a multiplication of the incoming optical
power per unit area (see Table 1 in Appendix 4) times the area of the solar cell (4.25 cm2).
 - cell efficiency [dimensionless] .   Pmax P : power output as a ratio of power input to the
in
cell.
Dr. Radu Florescu
Dr. Vladislav Shteeman
19
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
List of definitions
Series resistance Rseries - resistance due to the resistance of the metal contacts, ohmic losses
in the front surface of the cell, impurity concentrations, and junction depth. Ideally, the
series resistance should be zero ( Rseries  0 ).
Shunt resistance Rshunt - resistance, representing the losses due to surface leakage along the
edge of the cell or due to crystal defects. Ideally, the shunt resistance should be infinite
( Rshunt   ).
Dr. Radu Florescu
Dr. Vladislav Shteeman
20
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Appendix 2 : Cable connection of the switching matrix
and SCS 4200 I-V analyzer for I-V measurements of Solar
cell.
Figure 12. Standard cable connection (all the experiments except Solar Cell).
Dr. Radu Florescu
Dr. Vladislav Shteeman
21
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Figure 13. Solar cell cable connection.
Dr. Radu Florescu
Dr. Vladislav Shteeman
22
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Appendix 3 : Kite settings for I-V measurements.
1. Making Connections to the Solar Cell for I-V Measurements:
Figure below illustrates a solar cell connected to the Model 4200-SCS for I-V measurements.
One side of the solar cell is connected to the Force and Sense terminals of SMU1; the other
side is connected to the Force and Sense terminals of the ground unit (GNDU) as shown.
Using a four-wire connection eliminates the lead resistance that would otherwise affect this
measurement’s accuracy. With the four-wire method, a voltage is sourced across the solar
cell using one pair of test leads (between Force HI and Force LO), and the voltage drop across
the cell is measured across a second set of leads (across Sense HI and Sense LO). The sense
leads ensure that the voltage developed across the cell is the programmed output value and
compensate for the lead resistance.
Dr. Radu Florescu
Dr. Vladislav Shteeman
23
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
2. pin connection scheme:
SMU 1 (cables 1 and 2)
GND (cables 3 and 4)
3. I-V Keithley settings
Connect pins
Note that because of simultaneous usage of “force” and “sense” inputs, pin connection
must be done manually.
Dr. Radu Florescu
Dr. Vladislav Shteeman
24
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
In order to connect pins (as shown on the figure above), do the following steps:




press “local” button on the switching matrix panel
take the light pen, connected to the matrix, bring it to the close proximity of the A1
cell of the matrix, and press once the button on the pen (A1 cell will light up).
repeat for B2, D3 and E4 matrix cells
press “copy” button to save the connections
forward bias settings
Dr. Radu Florescu
Dr. Vladislav Shteeman
25
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Expected results – forward bias
Use the yellow-greed button
(“append”) to run the series of measurements of I-V
characteristics under different lightening conditions. DO NOT use the green button
(“override”): it overrides your previous measurements.
Dr. Radu Florescu
Dr. Vladislav Shteeman
26
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Appendix 4 : Solar Simulator
A solar simulator (also artificial sun) is a device that provides illumination approximating
natural sunlight. The purpose of the solar simulator is to provide a controllable indoor test
facility under laboratory conditions, used for the testing of solar cells, sun screen, plastics, and
other materials and devices.
In this experiment, you will use Newport Corp. Solar simulator with Xenon Short Arc Lamp. This
Solar Simulator provides close spectral match to solar spectra. The match is not exact but better
than needed for many applications.
For the supplied (electrical) power of 80 W, this lamp produces light with the intensity (per unit
area) of ~ 0.04 W
, i.e. approximately ½ of the intensity of Solar light. Incoming electrical
cm 2
power and outgoing optical power of the Solar simulator are shown in


Table 1.
Newport Solar simulator (Xenon lamp) with
controller unit.
Cut – away view of a Newport Solar simulator
Table 1. Incoming electrical power and outgoing optical power of the Solar simulator.
Electrical power
supplied to the Solar
simulator [W]
Output optical power
per unit area [W/cm2]
Pin [W], optical power, which
can be transformed into the
electrical power
100
100 + ND2
100 + ND 4
90
0.065
0.019
0.0125
0.056
0.276
0.08
0.053
0.238
Dr. Radu Florescu
Dr. Vladislav Shteeman
27
Output
optical
power
[W/cm2]
times photovoltaic
cell area (4.25 cm2)
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
80
0.04
0.17
Appendix 5 : Neutral Density (ND) optical filters.
Neutral density (ND) filters are used to attenuate the intensity of a light beam. An ideal
neutral density filter reduces intensity of all wavelengths of light equally.
The number after ND abbreviation means the “reduction power” of the filter. For example,
ND2 reduces twice the incoming power (transmittance 50%), ND4 reduces fourth the
incoming power (transmittance 25%), ND8 reduces eights the incoming power
(transmittance 12.5%), etc.
In this experiment you will use a set of simple photo ND
filters. Unfortunately, since those filters are NOT scientific
grade, they strongly cut the incoming optical power at the
near IR wavelengths (   0.65 m ). Nevertheless, since we
do not issue the question “what part of the solar spectrum
produces the photocurrent”, they still can be used to
attenuate the incoming optical power.
Dr. Radu Florescu
Dr. Vladislav Shteeman
28
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Bibliography
1
Solar cell – wikipedia: http://en.wikipedia.org/wiki/Solar_cell
2
“Photovoltaic measurements: testing the electrical properties of today’s solar cells”. Keithley
Instruments, 2009.
“Making I-V and C-V measurements on solar / photovoltaic cells using the model 4200 SCS
Semiconductor Characterization System”. Keithley Instruments – Application Note series (No
2876).
3
A. Chelly, “Amorphous Silicon Solar Module”, Lab manual - Advanced Semiconductor Devices
Lab (83-435), School of Engineering of Bar-Ilan University.
4
B. Van Zeghbroeck, “Principles of semiconductor devices”, Lectures – Colorado University,
2004.
5
B. Streetman, S. Banerjee, “Solid state electronic devices” (6th edition), Prentice Hall, 2005.
6
R.F. Pierret, "Semiconductor Device Fundamentals", Addison-Wesley 1996.
Dr. Radu Florescu
Dr. Vladislav Shteeman
29
Department of Electrical and Electronic Engineering
ORT Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Preparation Questions
1. Explain (in short) the principle of operation of solar cell
2. Plot equivalent circuit of solar cell
3. Plot (on a single figure) qualitative graphs of a dark and illuminated solar cell I-V
characteristics (Hint: see “Expected results” in Appendix 3)
4. Plot a single qualitative “upside down” graph (i.e. graph –I vs V) of illuminated solar cell IV characteristics. On the graph, indicate the following parameters:
 I max - maximum power current
 I SC - short circuit current
 Vmax - maximum power voltage
 VOC - open circuit voltage
 Pmax - maximum power point
(Hint: see the figure in Appendix 1)
5. Why must a solar cell be operated in the 4th quadrant of the junction I-V characteristics ?
(Hint: see Streetman “Solid State Electronic Devices”, 6th edition, Chapter 8, problem 8.7)
Dr. Radu Florescu
Dr. Vladislav Shteeman
30