Department of Electrical & Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Semiconductor Devices - 31820
Solar Cell
(photovoltaic cell)
July 31, 2017
Dr. Radu Florescu
Dr. Vladislav Shteeman
Department of Electrical and Electronic Engineering
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 and saturation current I sat
1.2. Series resistance Rseries
1.3. Ideality factor n
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
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
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 .
Dr. Radu Florescu
Dr. Vladislav Shteeman
4
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
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:
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:
Dr. Radu Florescu
Dr. Vladislav Shteeman
5
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
I D R series 
 VD nkT

q
I D  I sat  e
 1




(3)
( 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 Rseries 
 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 


VD  I D Rseries
nkT q

ID 
 I sat e
 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
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 and saturation current I sat .
Rshunt and I sat 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 should be performed in the dark.
Dr. Radu Florescu
Dr. Vladislav Shteeman
7
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Figure 5. Explanation to calculation of Rshunt and I sat of solar cell (after [2]).
Rshunt and I sat can be calculated from the linear fit of the I-V graph:
Rshunt 
1
, I sat  free term
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).
Dr. Radu Florescu
Dr. Vladislav Shteeman
8
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
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]).
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  .
Dr. Radu Florescu
Dr. Vladislav Shteeman
9
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
2.4.
Evaluation of ideality factor n .
Knowledge of Rseries , Rshunt and I sat allows one to estimate (from the dark forward bias
measurements) the ideality factor n . As it follows from the Eq. (4), for the region of
 VD  I D Rseries  
  1 holds),
nkT q



voltages VD  0.15 V (i.e. when exp 
V  I D Rseries
ID  D
 I sat e
Rshunt
VD  I D Rseries 
nkT q
(8)
Or

 V  I D Rseries
V  I D Rseries 
 I sat   D
ln   I D  D

Rshunt
0.027 n



(9)
(where kT q at the room temperature was replaced with 0.027 [V]).


V  I D Rseries 
 I sat  vs V D  I D Rseries  . The acquired
One can make graph ln   I D  D

Rshunt



curve should be approximately linear. The slope of this curve should be equal to
1
(see Figure 8 for details).
0.027 n
Figure 8. Explanation to computation of ideality factor n.
Dr. Radu Florescu
Dr. Vladislav Shteeman
10
Department of Electrical and Electronic Engineering
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
2.
3.
Dr. Radu Florescu
Dr. Vladislav Shteeman
11
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
4.
Appendix 2 for details about the cables connection).
5. 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.
6. Measure the area of the solar cell.
I-V characteristics measurements
Note: Before executing the measurements and processing the acquired data, save this
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#[email protected]” and “fwd-ivsweep#[email protected]” to the
Excel template.
data solar cell
processing (empty) new 14.01.2017.xlsx
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
IMPORTANT: in this experiment you use Solar simulator lamp. DO NOT operate
the simulator under power supply 150 W and above 200 W. Normal operational
mode of the lamp, as defined by the manufacturer, is 150 W – 200 W.
Dr. Radu Florescu
Dr. Vladislav Shteeman
12
Department of Electrical and Electronic Engineering
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 190 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. Repeat the measurements (steps 5 - 6) for additional 4 lamp’ supplied powers (e.g.
180 W, 170 W, 160 W, 150 W). (Use “set” button on the controller panel (press and
hold 2 seconds) and arrows buttons to set the power, supplied to the lamp, to the
required value, and wait for 2 minutes until the lamp’ radiation will be stabilized.)
SAVE ALL THE RESULTS in the Keithley program.
Dr. Radu Florescu
Dr. Vladislav Shteeman
13
photovoltaic
cell
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
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 and saturation current Rshunt and I sat . From the dark I-V
measurement at the reverse bias, evaluate the shunt resistance Rshunt and I sat of the
solar cell, as explained in the subsection “Evaluation of the shunt resistance Rshunt and
saturation current I sat “ (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 Rseries “ (see p. 8).
3. Ideality factor n . From the dark I-V measurements at the forward bias in the voltage
region VD  0.15 V  , evaluate the ideality factor, n , as explained in the subsection
“Evaluation of ideality factor n ” (see p.10).
4. 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
FF 
Intensity 1
Intensity 2
Intensity 3
Intensity 4
Intensity 5
(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) ).
Dr. Radu Florescu
Dr. Vladislav Shteeman
14
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
5. 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
d) VOC vs Pin
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
15
FF 
Department of Electrical and Electronic Engineering
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 9)

Shielded probe station (SPS) with the Solar simulator lamp (Figure 10)

Photovoltaic cell (Figure 12)

Portable power meter (Figure 11)
Lamp controller
Lamp controller
Keithley 708A
Switching Matrix
Solar simulator lamp
Monitor
Photovoltaic cell
Keithley SCS 4200 I-V
AND Parameter analyzer
Figure 10. Shielded probe station (SPS) with
the Solar simulator lamp and controller.
Figure 9. Keithley measurement setup
Photovoltaic cell
area is 4.25 cm2
Figure 12. Photovoltaic cell.
Figure 11. Power meter
Dr. Radu Florescu
Dr. Vladislav Shteeman
16
Department of Electrical and Electronic Engineering
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
17
Department of Electrical and Electronic Engineering
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

I dark - dark current A

I satdark - saturation dark current (saturation
different currents in the dark A

current of ideal diode) A
I rec  - generation-recombination current

I satrec  - saturation current of generation-recombination current A






in the depletion region 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 : power output as a ratio of power input to the
Pin
cell.
Dr. Radu Florescu
Dr. Vladislav Shteeman
18
Department of Electrical and Electronic Engineering
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
19
Department of Electrical and Electronic Engineering
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 13. Standard cable connection (all the experiments except Solar Cell).
Dr. Radu Florescu
Dr. Vladislav Shteeman
20
Department of Electrical and Electronic Engineering
Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Figure 14. Solar cell cable connection.
Dr. Radu Florescu
Dr. Vladislav Shteeman
21
Department of Electrical and Electronic Engineering
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
22
Department of Electrical and Electronic Engineering
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
23
Department of Electrical and Electronic Engineering
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
24
Department of Electrical and Electronic Engineering
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
25
Department of Electrical and Electronic Engineering
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
26
Output
optical
power
[W/cm2]
times photovoltaic
cell area (4.25 cm2)
Department of Electrical and Electronic Engineering
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
27
Department of Electrical and Electronic Engineering
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
28
Department of Electrical and Electronic Engineering
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
29