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Solar Cell(photovoltaic cell)
May 19, 2023
Department of Electrical & Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Semiconductor Devices - 31820
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 R shunt and saturation current I sat
1.2. Series resistance R series
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 Imax such as
Pmax=ImaxVmax .
2.3. Cell efficiency η=
PmaxPin where Pin is the power of the incoming light.
2.4. Open Circuit Voltage V OC (output current I=0 ).
2.5. Short Circuit Current I SC (output voltage V=0 ).
2.6. Fill Factor FF=ImaxVmax / ( I SC V OC )
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:
In solar cell, there are 2 parasitic resistances: series resistance R seriesand shunt resistance
R shunt , which impact the performances of photovoltaic device (see Figure 3 and List of
definitions in for definitions of R series and R shunt ). Ideally, series resistance should be zero (
Rseries=0 ), while shunt resistance should be infinite (R shunt=∞ ).
1. Model of solar cell I-V characteristics [2],[3].
At the 1 st 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 R series .
Dr. Radu Florescu Dr. Vladislav Shteeman 4
Figure 3. Equivalent circuit of solar cell (after [2]).
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
As opposite to a “standard” diode, R series affects I-V characteristics of solar cell all along, not
only for V D>V 0 (where V 0 is a built-in voltage). R series 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,
I D=I ( dark )=I sat ( dark )(e (V D−I D Rseries)
kT /q −1)⏟dark current (1)
(where I D , V D - 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 2 nd 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:
I D=I ( dark )+ I ( gen )=I sat ( dark )(e (V D−I D Rseries)
kT /q −1)⏟dark current
+ I sat ( gen)(e
(V D−I D R series)2kT /q −1)⏟
generation current (2)
(I sat ( gen ) - saturation current due to generation-recombination only)
Dr. Radu Florescu Dr. Vladislav Shteeman 5
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
The usual practice is to introduce an ideality factor, n , which allows to account for both
currents in a single expression:
I D=I sat(e
(V D−I D Rseries )nkT /q −1)
(3)
(I sat - saturation current due to both generation current and “dark” current)
At the 3 rd approximation , one should account for influence of shunt (parallel) resistance,
R shunt . Presence of R shunt 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
R shunt 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 R shunt 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 R shunt gives:
I D=V D−I D R series
R shunt+ I sat
(e (V D−I D Rseries)nkT /q −1)
(4)
At the 4 th 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:
Dr. Radu Florescu Dr. Vladislav Shteeman 6
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
I D=V D−I D R series
R shunt+ I sat
(e (V D−I D Rseries )nkT /q −1)
⏟different currents in the dark
− I ( light )⏟light current
(5)
2. Evaluation of different physical parameters of solar cell from
the I-V measurements.
2.1. Evaluation of Imax ,Vmax ,I SC , V OC , 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]).
Dr. Radu Florescu Dr. Vladislav Shteeman 7
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
2.2. Evaluation of the shunt resistance R shunt and saturation current I sat .
R shunt 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.
Figure 5. Explanation to calculation of R shunt and I sat of solar cell (after [2]).
R shunt and I sat can be calculated from the linear fit of the I-V graph:
R shunt=1
slope, I sat=free term
(6)
The expected value of R shunt in this experiment is~400 [Ω ] .
2.3. Evaluation of series resistance R series .
We’ll estimate series resistance R series 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
Figure 6. Explanation to the series resistance measurement by the Slope method (after [2]).
The current δ I below the I SC , I=I SC−δ I , is picked on both I–V curves. The currents I(1)=I SC (1 )−δ I and I(2)=I SC (2 )−δ I correspond to the voltages V (1 ) and V (2 ). The series resistance is then:
R series=ΔVΔI
=V (1 )−V (2)
I (2 )−I (1)=
V (1)−V (2 )
I SC (2)−I SC (1)= 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 Figure7).
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 [Ω ] .
Dr. Radu Florescu Dr. Vladislav Shteeman 9
I SC (1 )
I SC (2 )
R series=ΔVΔI
=V (1 )−V (2)
I (2 )−I (1)
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 R series , R shunt 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
voltages V D>0 .15 [V ] (i.e. when exp( (V D−ID Rseries )
nkT /q )>>1 holds),
ID=V D−I D R series
Rshunt+ I sat e
(V D−I D Rseries )nkT /q
(8)
Or
ln ((I D−V D−I D Rseries
R shunt )/I sat)=V D−I D Rseries
0 .027n(9)
(where kT /q at the room temperature was replaced with 0.027 [V]).
One can make graph ln ((I D−
V D−ID Rseries
Rshunt )/ I sat) vs (V D−I D Rseries ). The acquired
curve should be approximately linear. The slope of this curve should be equal to
10 .027n (see Figure 8 for details).
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 analysisPreparation 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 for details about the cables connection).
2. Place the box with the solar cell and light power sensor the chunk table in the
Shielded probe station.
3. Connect the “+” contact of the solar cell to the 1st and 2nd cables and the “-” contact
to the 3rd and 4th cables.
4. Connect the light power sensor to the Power meter.
I-V characteristics measurementsNote: 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.
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 ).
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.
Dr. Radu Florescu Dr. Vladislav Shteeman 11
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
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.
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.
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 12
light spot from the lamp
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 R shunt and I sat . From the dark I-V
measurement at the reverse bias, evaluate the shunt resistance R shunt and I sat of the
solar cell, as explained in the subsection “Evaluation of the shunt resistance R shunt and
saturation currentI sat “ (see p. 8).
2. Series resistance R series. From the light I-V measurements at the forward bias,
evaluate the series resistance R series of the solar cell, as explained in the subsection
“Evaluation of series resistance R series “ (see p. 8).
3. Ideality factor n . From the dark I-V measurements at the forward bias in the voltage
region V D≥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 Imax ,Vmax ,I SC , V OC , Pmax ,FF , as
explained in the subsection “Evaluation of Imax ,Vmax ,I SC , V OC , Pmax ,FF ” (see p. 7).
Fill in the following Table (in the Excel file):
Pin [Watt /cm2 ] Imax [ A ] Vmax [ V ] ISC [ A ] V OC [ V ] Pmax [Watt ] FF ηIntensity 1Intensity 2Intensity 3Intensity 4Intensity 5
Dr. Radu Florescu Dr. Vladislav Shteeman 13
Department of Electrical and Electronic Engineering 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) ).
5. Present graphically the data, acquired in the Table above. Namely, build in Excel (and
include in the Final report) the following graphs:
a) Imax vs Pin b) Vmax vs Pin c) I SC vs Pin d) V OC vs Pin
e) Pmax vs Pin f) FF vs Pin g) η 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 (V D ) for forward and for reverse bias)
[2] A set of I-V characteristics of solar cell under different lightening intensities|ID (V D )| (a single
graph)
[3] Shunt resistance R shunt (a single value)
[4] Series resistance R series (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 /cm2 ] Imax [ A ] Vmax [ V ] ISC [ A ] V OC [ V ] Pmax [Watt ] FF ηIntensity 1Intensity 2Intensity 3Intensity 4Intensity 5
[8] The following graphs (2 graphs, including each 3-4 subplots):
Dr. Radu Florescu Dr. Vladislav Shteeman 14
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
a) Imax vs Pin b)Vmax vs Pin c) I SC vs Pin d)V OC vs Pin
e) Pmax vs Pin f) FF vs Pin g)η vs Pin
Dr. Radu Florescu Dr. Vladislav Shteeman 15
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 11)
Portable power meter (Figure 12)
Dr. Radu Florescu Dr. Vladislav Shteeman 16
Keithley 708A Switching Matrix
Monitor
Keithley SCS
4200 I-
Figure 9. Keithley measurement setup
simulator lamp
Lamp controller
Photovoltaic cell
Figure 10. Shielded probe station (SPS) with the Solar simulator lamp and controller.
Figure 11. Photovoltaic cell.
Figure 12. Power meter
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
AcknowledgementElectrical 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 Bar-Ilan University. We would like to thank Dr. Abraham Chelly for the granted manual.
Dr. Radu Florescu Dr. Vladislav Shteeman 17
Keithley SCS
4200 I-
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
R series- series resistance [Ω ]
R shunt - shunt resistance [Ω ]
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 ( gen ) - generation current
in the depletion region[ A ]
I sat ( gen ) - saturation current of generation 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 V D=0 ) [ A ] V OC - open circuit voltage (output current I D=0 ) [ V ] V D - voltage (bias) applied to the diode (solar cell) [ V ] V 0 - Built-in voltage
Imax - 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=ImaxVmax / ( I SC V OC ) [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 )
kTq - thermal voltage [ V ] . For the room temperature: T=300∘ K kT /q=0 .026 [ V ]
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.
Dr. Radu Florescu Dr. Vladislav Shteeman 18
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
η - cell efficiency [dimensionless] . η=
PmaxPin : power output as a ratio of power input to the
cell.
List of definitions
Series resistance R series- 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 (R series=0 ).
Shunt resistance R shunt - 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
(R shunt=∞ ).
Dr. Radu Florescu Dr. Vladislav Shteeman 19
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Dr. Radu Florescu Dr. Vladislav Shteeman 20
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 21
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 22
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 23
Department of Electrical and Electronic Engineering Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
2.pin connection scheme:
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
SMU 1 (cables 1 and 2) GND (cables 3 and 4)
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 25
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 26
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 cm2 ], i.e. approximately ½ of the intensity of Solar light. Incoming electrical
power and outgoing optical power of the Solar simulator are shown in Table 1.
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 0.065 0.276100 + ND2 0.019 0.08100 + ND 4 0.0125 0.053
90 0.056 0.23880 0.04 0.17
Dr. Radu Florescu Dr. Vladislav Shteeman 27
Newport Solar simulator (Xenon lamp) with controller unit.
Cut – away view of a Newport Solar simulator
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
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 (λ>0 .65 [ μm ] ). 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 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 Braude College of Engineering
Advanced Laboratory for Characterization of Devices – 31820
Preparation Questions
1. Explain (in short) the principle of operation of solar cell2. Plot equivalent circuit of solar cell3. Plot (on a single figure) qualitative graphs of a dark and illuminated solar cell I-V
characteristics (Hint: see “Expected results” in )4. Plot a single qualitative “upside down” graph (i.e. graph –I vs V) of illuminated solar cell I-
V characteristics. On the graph, indicate the following parameters:
Imax - maximum power current
I SC - short circuit current
Vmax - maximum power voltage
V OC - 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