SIM UNIVERSITY
SCHOOL OF SCIENCE AND TECHNOLOGY
SIMULATION OF SOLAR PHOTOVOLTAIC
CELLS AND MODULES
STUDENT: AUNG MYAT THU (B0706644)
SUPERVISOR: DR. JIANG FAN
PROJECT CODE: JAN2010/ENG/0080
A project report submitted to SIM University in partial fulfilment of the
requirements for the degree of
Bachelor of Electronics Engineering
November 2010
ABSTRACT
The cost of fuel is going higher and overuse of fossil fuel environmentally unfriendly.
Nowadays, countries and governments are encouraging to use the renewable energy like solar
or wind energy. Therefore, it is important to understand the energy performance resulting
from photovoltaic cell. There are a few models that predict energy production, but they
require a large amount of input data that are not available during the design phase. In this
project, we will study and build a simulation model using Pspice to predict the energy
performance under different circumstances.
PSpice is the program, which carries out the actual simulation of the circuit. Normally, one
describes a circuit (using the PSpice language) on a text editor. PSpice simulates the circuit,
and calculates its electrical characteristics. If we need a graphical output, PSpice can transfer
its data to the Probe program for graphing purposes. Also Pspice is a simulation program that
models the behaviour of a circuit.
We will also study of solar background and its electrical characteristic. With this simulation
model, it will help us to study the impact of PV cell internal material parameters. Moreover,
this shall be applied in the analysis cell temperature and partial shade on the performance of a
PV cell, etc.
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ACKNOWLEDGEMENTS
I would like to express my utmost gratitude and appreciation to my academic supervisor Dr.
Jiang Fan from Singapore Polytechnic, for his patient, guidance and understanding during the
entire course of my project, answer my questions on the experiment setups and other queries.
I also would like to thank my immediate supervisor from STMicroelectronics Pte Ltd, Mr.
David Ong for the arrangement of Annual Leaves and Time OFFs whenever necessary
throughout my part-time study.
Last but not least, I would like to express my greatest appreciation to my family for their
emotional support throughout the entire course of my study.
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TABLE OF CONTENTS
Page
ABSTRACT
i
ACKNOWLEDGEMENT
ii
LISTS OF FIGURES
iii
LIST OF TABLES
iv
CHAPTER ONE
Introduction
1
1.1 Project Objectives
1
1.2 Overall Objectives
1
1.3 Proposed approach and methods to be deployed
2
1.4 Layout of the Project report
3
1.4.1 Criteria and targets for judging the progress of the project
3
1.4.2 Lists of skills need to achieve targets
3
1.4.3 Identification of strengths and weaknesses
4
1.4.4 Priorities for improving the skills
4
1.4.5 Immediate targets
4
1.5 Summary of Results
4
CHAPTER TWO
Investigation of Project Background
6
2.1 Review the history on the Photovoltaic system (PV)
6
2.2 Review on the Photovoltaic system
7
2.3 Photovoltaic Cell Parameters
10
2.4 Overview study of Pspice
11
CHAPTER THREE
Experimental set up and Electrical characteristics of the solar cell
13
3.1 Pspice set up
13
3.2 Electrical characteristics of the solar cell
14
3.2.1 Short circuit current (Isc)
14
3.2.2 Open circuit voltage (Voc)
16
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3.2.3 Maximum Power Point (MPP)
17
3.2.4 Fill Factor (FF) and Power Conversion Efficiency
19
CHAPTER FOUR
Generalized model of a solar cell
22
4.1 Series resistance
22
4.2 Shunt resistance
23
4.3 Recombination
24
4.4 Temperature Effects
25
4.5 Effects of space radiation
26
CHAPTER FIVE
Solar Cell in series and parallel and comparison
27
5.1 Series connection of two solar cells
27
5.2 Shunt (Parallel) connection of Solar Cells
28
5.2.1 Shadow effects
5.3 The Terrestrial PV module
31
33
CHAPTER SIX
Conclusion and Recommendation
35
6.1 Conclusion
35
6.2 Recommendation
35
CHAPTER SEVEN
Critical Review and Reflection
36
REFERENCES
38
APPENDIXS
39
Appendix A
39
Appendix B
40
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Appendix C
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Lists of Figures
Page
Figure 2.1 a solar cell made from monocrystalline silicon wafer
8
Figure 2.2 Block diagram for stand-alone PV system
10
Figure 3.1 Pspice A/D demo window
13
Figure 3.2 Solar cells IV characteristic without illumination
14
Figure 3.3 I(V) characteristic of the solar cell model
15
Figure 3.4 I(V) plots of a solar cell under several irradiance values: 200, 400, 600,
17
800 and 1000 W/m2
Figure 3.5 Plot of the power values under different values of irradiances
18
Figure 3.6 Series resistance effects on fill factor
20
Figure 4.1 Series resistance effects, I(V) characteristic for series resistance values
22
Figure 4.2 Effects of the shunt resistance on the I(V) characteristic
23
Figure 4.3 Subcircuit including two diodes and series and shunt resistors
24
Figure 4.4 Effects of the recombination diode
24
Figure 4.5 Effects of temperature
26
Figure 4.6 Degradation of the characteristic of the silicon solar cell for various
26
space radiation fluencies
Figure 5.1 Two solar cells in series
27
Figure 5.2 Simulation result of two identical solar cells in series
28
Figure 5.3 Comparison between one cell and two identical solar cells in series
28
Figure 5.4 I(V) Characteristic of two solar cells in series under different irradiance
29
values of cells
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Figure 5.5 Voltages drop of the two cells under different irradiance
29
Figure 5.6 Power delivered (positive) or consumed (negative) on the two solar cells
30
unevenly illuminated
Figure 5.7 Two solar cells in parallel with different irradiance
31
Figure 5.8 Two parallel cells under shadowed (CASE A)
31
Figure 5.9 One cell at full irradiance and the other at completely shadowed
32
(CASE B)
Figure 5.10 One cell at full irradiance and the other at partially shadowed
32
(CASE C)
Figure 5.11 Pspice model for the PV module subcircuit
33
Figure 5.12 I(V) characteristic and output power of a PV module
34
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List of Tables
Page
Table 2.1 early developments of photovoltaic
7
Table 3.1 Short circuit current and open circuit voltage under various irradiance
17
Table 3.2 Pspice result for several irradiance values
19
Table 3.3 Series resistance and its affect on the fill factor
21
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Chapter 1
Project Definition
1.1 Project objective
This project aims to setup computer modeling for a PV cell/module so as to analyze the
impacts of different parameters on outputs of a solar cell/module.
The project will include the following main tasks:
1. Understanding of solar cells and module
2. The analysis on the performance of solar cell/module under different operating
conditions
3. Learning of simulation software, Pspice
4. Modelling of solar cell/module needs to be built using computer software
1.2 Overall objective
The reason of studying this project is due to the increasing demands of alternative energy
resources. As the conventional energy sources are dwindling fast, the solar photovoltaic
energy offers a very promising alternative, because it is free, abundant, pollution free and
distributed throughout the earth. Therefore, accurate, reliable, and easy to apply methods for
predicting the energy productions of photovoltaic panels are needed to identify optimum
photovoltaic systems.
However, it is expensive to simulate using physical solar panels to study the performance of
the solar photovoltaic cells. Computer-based simulation is a useful means to study the
performance of solar photovoltaic that is affected by various factors such as solar irradiance,
cell temperature, operational conditions and different technologies. The power output from
the photovoltaic cell mainly depends on the light intensity, the cell temperature, the panel’s
orientation, its size and surface conditions. The light intensity affects primarily the amount of
current produced, while the cell temperature controls the voltage produced. As the cell
temperature increases under the same solar irradiance, the voltage of the cell is reduced and
its current remains the same, which reduces the output power. All of these factors need to be
taken in consideration to accurately predict the energy production.
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Photovoltaic (PV) systems consist of a PV generator (cell, module, and array), energy storage
devices (such as batteries), AC and DC convectors and elements for power conditioning.
The objective of this project is to build a workable simulation model using Pspice PV cell.
The simulation will be considered in the model to obtain an accurate, reliable, and easy-toapply method for predicting the energy production of PV cell and measuring the impact of
different parameters (temperature and irradiance) on the performance of PV cell operation
throughout the simulation
This project includes the following objects:
 To write the source code model using Pspice for PV cell to predict the energy
production
 To investigate impacts of internal material resistance of a cell on its operational
performance
 To examine impact of cell temperature on the cell energy production via simulation
study
 To simulate the PV cells in series and parallel
 To simulate the effect of partial shade on output of PV cell energy production through
the simulation
 To simulate PV module
1.3 Proposed approach and method to be employed
Pspice model for photovoltaic cells will be carried out in this project. Using SPICE, the tool
of choice for circuits and electronics designers, this project will highlight the increasing
importance of modeling techniques in the quantitative analysis of PV systems. It will provide
a unique, self-contained guide to the modeling and design of PV systems.
Firstly, need to learn how to create and do simulation on Pspice as the project’s requirements
and new software to me. After learning Pspice, PV cells in series were simulated in Pspice to
achieve the desired output voltage. After that I created the cells in parallel to get the desired
amount of current source capabilities. We will use a PSPICE model to simulate I-V (CurrentVoltage) and P-V (Power- Voltage) characteristics of a PV module and also studied the PV
system under various circumstances like shading effect, temperature, diode model parameters,
series and shunt resistance etc.
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Lastly, need to compare the data collect using Pspice to commercial PV cell as well as other
simulation model like matlab.
1.4 Skills review
1.4.1 Criteria and targets for judging the progress of the project
-
The performance of the project will be measured based on our project goals and
proposed project approaches.
-
According to scheduled project plan, the targets will be set and the progress of the
project will be monitored.
Criteria/Targets
Dateline
Status
Project Proposal and Approval
14 Jan 2008
Completed
Literature review
7 Mar 2010
Completed
Project initial report
8 Mar 2010
Completed
Study of Pspice and PV system 20 May 2010
Completed
Simulation of PV module
08 Sep 2010
Completed
Submission of Final Report
15 Nov 2010
Completed
Oral Presentation
27 Nov 2010
On-going
using Pspice
1.4.2 Lists of skills need to achieve targets
-
Ability of searching resources (literature review and journal review papers)
-
Pspice and simulink skills
-
Understanding of PV system
-
Enhancement in semi conductor device
-
Project management skills
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-
Technical report writing skills
-
Presentation and effective communication skills
1.4.3 Identification of strengths and weaknesses
Strengths
Weaknesses
Ability of searching resources
Understanding of PV system
Knowledge of simulink
New exposure to Pspice
Project management skills
Technical report writing skills
Presentation and effective
communication skills
1.4.4 Priorities for improving the skills
-
In order to improve my understanding of PV system, I will study simple and more
details PV systems for better understanding.
-
To enhance my understanding of Pspice, I will start with simple tutorials lessons
and then after learn the PV system using Pspice.
-
To improve my technical report writing skills, I will read more thesis reports and
learn from them.
1.4.5 Immediate targets
As the next stage of the project after initial report, I will study PV system and Pspice. Firstly,
Pspicpe software will be studied and practiced simple tutorials. Then will study of PV system
simulation using Pspice. Finally, simulation of PV system using Pspice and compare the
results with other models.
1.5 Summary of Results
The results for all the experiments in this project are presented in chapter 3, 4 and chapter 5
of this thesis. In summary, first, we will study the electrical characteristic of solar cell like
open circuit voltage, short circuit current, fill factor and maximum power. Second, we will
study on generalized model of a solar cell under various effects like irradiance and
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temperature. Lastly we will study the series and parallel of cells under different
circumstances and introduction study on PV module. All of the related Pspice code will be
mentioned in Appendix C.
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Chapter 2
INVESTIGATION OF PROJECT BACKGROUND
A solar cell is a device that converts the energy of sunlight directly into electricity by the
photovoltaic effects. Sometimes the term solar cell is reserved for devices intended
specifically to capture energy from sunlight such as solar panels and solar cells, while the
term photovoltaic cell is used when the light source is unspecified. Assemblies of cells are
used to make solar panels or solar modules that are employed to form photovoltaic arrays.
Photovoltaic is the field of technology and research related to the application of solar cells in
producing electricity for practical use. The energy generated this way is an example of solar
energy (also known as solar power). The increasing demands of alternative energy resources
as the conventional energy sources are dwindling fast, the solar photovoltaic energy offers a
very promising alternative, because it is free, abundant, pollution free and distributed
throughout the earth.
2.1 Review the history on the Photovoltaic system (PV)
Scientists have known of the photovoltaic effect for more than 170 years. The photovoltaic
effect was first recognized in 1839 by French physicist A. E. Becquerel. However, the first
solar cell was built until 1883 by Charles Fritts [7], who coated the semiconductor selenium
with an extremely thin layer of gold to form the junctions. The device was only around 1%
efficient. The modern age of solar power technology arrived in 1954 when Bell Laboratories
by Gerald Pearson, Daryl Chapin and Calvin Fuller, experimenting with semiconductors,
accidentally found that silicon doped with certain impurities was very sensitive to light. This
resulted in the production of the first practical solar cells with a sunlight energy conversion
efficiency of around 6 percent. In 1958, the Vanguard satellite employed the first practical
photovoltaic generator producing a modest one watt. Table 2.1 showed early development of
photovoltaic. In the 1960s, the space program continued to demand improved photovoltaic
power generation technology. Early satellites needed a source of electrical power and any
solution was expensive. The development of solar cells for this purpose led to their eventual
use in other applications. Without this tremendous development effort, photovoltaic power
would be of little use today.
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Year
1839
Development
Antoine-César Becquerel, a French physicist, discovered the photovoltaic effect.
In his experiments he found that voltage was produced when a solid electrode in
an electrolyte solution was exposed to light
1877
W.G. Adams and R.E. Day observed the photovoltaic effect in solid selenium.
They built the first selenium cell and published “The action of light on selenium,”
in Proceedings of the Royal Society
1883
Charles Fritz built what many consider to be the first true photovoltaic cell. He
coated the semiconductor selenium with an extremely thin layer of gold. His
photovoltaic cell had an efficiency of less than 1%
1904
Albert Einstein published a paper on the photoelectric effect
1927
A new type of photovoltaic cell was developed using copper and the
semiconductor copper oxide. This device also had an efficiency of less than 1%.
Both the selenium and copper oxide devices were used in applications such as
light meters for photography
1941
Russell Ohl developed the silicon photovoltaic cell. Further refinement of the
silicon photovoltaic cell enabled researchers to obtain 6% efficiency in direct
sunlight in 1954
1954
Bell Laboratories obtained 4% efficiency in a silicon photovoltaic cell. They soon
achieved 6% and then 11%
1958
PV cells were first used in space on board the Vanguard satellite
Table 2.1 Early development of photovoltaic
2.2 Review on the Photovoltaic system
A photovoltaic (PV) system generates electricity by the direct conversion of the sun’s energy
into electricity. This simple principle involves sophisticated technology that is used to build
efficient devices, namely solar cells, which are the key to components PV system and require
semiconductor-processing techniques in order to be manufactured at low cost and high
efficiency. Detailed semiconductor processing techniques can be referred in Appendix.
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A photovoltaic system is a modular system because it is built out of several pieces or
elements, which have to be scaled up to build larger systems or scaled down to build smaller
systems. Photovoltaic systems are found in the Megawatt range and in the milliwatt range
producing electricity for very different uses and applications: from a wristwatch to a
communication satellite or a PV terrestrial plant, grid connected. The operational principles
though remain the same, and only the conversion problems have specific constraints.
Figure 2.1 A solar cell made from monocrystalline silicon wafer
Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline
silicon, microcrystalline silicon, cadmium telluride, and copper indium selenide/sulfide.The
elements and components of PV system are the photovoltaic devices themselves, or solar
cells packaged and connected in a suitable form and the electronic equipment required
interfacing the system to the other system components, namely:
-
A storage element in standalone systems;
-
The grid in grid-connected systems;
-
AC or DC loads, by suitable DC/DC or DC/AC converters.
Specific constraints must be taken into account for the design and sizing of these systems and
specific models have to be developed to simulate the electrical behavior.
There are some of the important definitions to know during this project to understand the
terms. The radiation of the sun reaching the earth, distributed over a range of wavelengths
from 300nm to 4 micron approximately, is partly reflected by the atmosphere and partly
transmitted to the earth’s surface. Photovoltaic applications used for space, such as satellites
or spacecrafts, have a sun radiation availability different from that of PV applications at the
wavelengths in a similar fashion to the radiation of a ‘black body’ following Planck’s law,
whereas at the surface of the earth the atmosphere selectively absorbs the radiation at certain
wavelengths. It is common practice to distinguish two different sun ‘spectral distributions’:
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(a) AM0 spectrum outside of the atmosphere.
(b) AM 1.5 G spectrum at sea level at certain standard conditions defined below.
Several important magnitudes can be defined: spectral irradiance, irradiance and radiation
as follows:
(a) Spectral irradiance I a – the power received by a unit surface area in a wavelength
differential d , the units are W / m 2 .
(b) Irradiance – the integral of the spectral irradiance extended to all wavelengths of interest.
The units are W / m 2 .
(c) Radiation – the time integral of the irradiance extended over a given period of time,
therefore radiation units are units of energy. It is common to find radiation data in J / m 2 day, if a day integration period of time is used, or most often the energy is given in
kWh / m 2 -day, kWh / m 2 -year depending on the time slot used for the integration of the
irradiance.
High-efficiency solar cells are a class of solar cell that can generate more electricity per
incident solar power unit (watt/watt). Much of the industry is focused on the most cost
efficient technologies in terms of cost per generated power. The two main strategies to bring
down the cost of photovoltaic electricity are increasing the efficiency of the cells and
decreasing their cost per unit area. However, increasing the efficiency of a solar cell without
decreasing the total cost per kilowatt-hour is not more economical, since sunlight is free.
Thus, whether or not "efficiency" matters depends on whether "cost" is defined as cost per
unit of sunlight falling on the cell, per unit area, per unit weight of the cell, or per unit energy
produced by the cell. In situations where much of the cost of a solar system scales with its
area (so that one is effectively "paying" for sunlight), the challenge of increasing the
photovoltaic efficiency is thus of great interest, both from the academic and economic points
of view.
Newer alternatives to standard crystalline silicon modules include casting wafers instead of
sawing, thin film (CdTe CIGS, amorphous Si, microcrystalline Si), concentrator modules,
'Sliver' cells, and continuous printing processes. Due to economies of scale solar panels get
less costly as people use and buy more — as manufacturers increase production to meet
demand, the cost and price is expected to drop in the years to come.
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A photovoltaic PV generator is the whole assembly of solar cells, connections, protective
parts, supports etc. In the present modeling, the focus is only on cell/module/array. Solar cells
consist of a p-n junction fabricated in a thin wafer or layer of semiconductor (usually silicon).
In the dark, the I-V output characteristic of a solar cell has an exponential characteristic
similar to that of a diode. When solar energy (photons) hits the solar cell, with energy greater
than band gap energy of the semiconductor, electrons are knocked loose from the atoms in
the material, creating electron-hole pairs. These carriers are swept apart under the influence
of the internal electric fields of the p-n junction and create a current proportional to the
incident radiation. When the cell is short circuited, this current flows in the external circuit;
when open circuited, this current is shunted internally by the intrinsic p-n junction diode. The
characteristics of this diode therefore set the open circuit voltage characteristics of the cell.
Figure 2.2 Block diagram for stand-alone PV system
2.3 Photovoltaic Cell Parameters
The fundamental electrical parameters of the solar module are defined
 Short circuit current (Isc)
 Open circuit voltage (Voc)
 Maximum power point current (Imp)
 Maximum power point voltage (Vmp)
 Maximum power (Pmax)
 Fill Factor (FF) and Power Conversion Efficiency
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This simple model is then generalized to take into account series and shut resistive losses and
recombination losses. Temperature effects are then introduced and the effects of space
radiation are also studied with a modification of the PSpice model. Details simulation on
these parameters will be discussed on next chapter.
2.4 Overview study of Pspice
OrCAD offers a total solution for user’s core design tasks: schematic- and VHDL-based
design entry; FPGA and CPLD design synthesis; digital, analog, and mixed-signal
simulation; and printed circuit board layout. What's more, OrCAD's products are a suite of
applications built around an engineer's design flow--not just a collection of independently
developed point tools. PSpice is just one element in OrCAD's total solution design flow. With
OrCAD’s products, user’ll spend less time dealing with the details of tool integration,
devising workarounds, and manually entering data to keep files in sync. The products will
help user build better products faster, and at lower cost.
OrCAD PSpice is a simulation program that models the behaviour of a circuit containing
analog devices. Used with OrCAD Capture for design entry, you can think of PSpice as a
software-based breadboard of the circuit that user can use to test and refine the design before
ever touching a piece of hardware.
Run basic and advanced analyses
PSpice can perform:
 DC, AC, and transient analyses, so user can test the response of your circuit to different
inputs.
 Parametric, Monte Carlo, and sensitivity/worst-case analyses, so you can see how your
circuit’s behavior varies with changing component values.
Use parts from OrCAD’s extensive set of libraries
The model libraries feature over 11,300 analog models of devices manufactured in North
America, Japan, and Europe.
Vary device characteristics without creating new parts
PSpice has numerous built-in models with parameters that you can tweak for a given device.
These include independent temperature effects.
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Model behaviour PSpice supports analog behavioural modelling, so you can describe
functional blocks of circuitry using mathematical expressions and functions.
The PSpice is an analog/digital circuit simulator, which calculates voltage and current in a
circuit under variety of different circumstances. This feature of PSpice is used to simulate a
circuit based model for PV cells/ modules and then to conduct behavioural study under
varying conditions of solar isolation including shading effect, temperature, diode model
parameters, series and shunt resistance etc. The study is very helpful in clearly outlining the
principles and the intricacies of PV cells/modules and may surely be used to verify impact of
different topologies and control techniques on the performance of different types of PV
system.
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Chapter 3
Experimental Set up and Electrical characteristics of the solar cell
3.1 Pspice set up
In this project, Pspice software is used for simulation of solar cell and its behaviours. Pspice
is the SPICE analog circuit and digital logic simulation that runs on personal computers,
hence the first letter ‘P’ in its name. It was developed by MicroSim and is used in electronic
design automation. MicroSim was bought by OrCAD which was subsequently purchased by
Cadence Design Systems. The name is an acronym for Personal Simulation Program with
Integrated Circuit Emphasis. Today it has evolved into an analog mixed signal simulator.
OrCAD can be used to simulate in two different ways, drawing the circuit and writing the
code. In this project, simulations are done by creating the codes. Most important thing about
writing the code is assigning the correct node.
3.1.1 Pspice work space
OrCAD version 16.3 demo had been used throughout the project. When Pspice A/D demo
opened, a window is shown in figure 3.1.
Figure 3.1 Pspice A/D demo window
We can write the Pspice code in the text file and can start doing simulation. It also can
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produce output file and error file.
3.2 Electrical characteristics of the solar cell
The dark and illuminated I(V) characteristics are analytically described and Pspice models
are introduced for the simplest model, composed of a diode and a current source. This simple
model is then generalized to take into series and shunt resistive losses and recombination
losses. Temperature effects are then introduced and the effects of space radiation are studied
in next chapters with a modification of the Pspice model.
3.2.1 Short circuit current (Isc)
A silicon solar cell is a simple diode circuit formed by a p-n junction. The IV curve of a solar cell
in the dark is the same IV characteristic as a diode with the light-generated current [13], as
illustrated in Figure 3.2.1. The light has the effect of shifting the IV curve. The value of the
current generated by the solar cell submitted to a given irradiance and voltage is given by
Figure 3.2 Solar cells IV characteristic without illumination
The case in photovoltaic is that a solar cell receives a given irradiance value and that the short
circuit current is proportional to the irradiance. In order to implement that in Pspice the value
of the short circuit current, is assigned to G-device which is a voltage-controlled current
source.
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Syntax for G-device
node+ node- control_node+ control_node- gain
In this project, the G-device used is named ‘girrad’ and is given by:
where G is the value of the irradiance in
. Above equation considers that the value of
is given at standard (AM1.5G, 1000
) conditions, which are the
conditions under which measurements are usually made. Solar cell manufacturers’ catalogues
provide these standard values for the short circuit current. Equation returns the value of the
short circuit current at any irradiance value, G, provided the proportionality between
irradiance and short circuit current holds. This is usually the case provided low injection
conditions are satisfied.
The example of subcircuit used in this project:
.subckt cell_1 300 301 302 params:area=1, j0=1, jsc=1
girrad 300 301 value={(jsc/1000)*v(302)*area}
d1 301 300 diode
.model diode d(is={j0*area})
.ends cell_1
As can be seen from subcircuit code, we have to assign unity to the parameters. The real
values are specified later when the subcircuit is included in a circuit.
In order to obtain I(V) characteristic, the solar cell subcircuit is connected in a measurement
circuit. Below is the I(V) characteristic of the solar cell model.
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Figure 3.3 I(V) characteristic of the solar cell model
From the above figure, the value of short circuit current of the cell can be gotten from the
intersection of the graph with the y-axis which is 4.342A in that case.
3.2.2 Open circuit voltage (Voc)
Another important electrical parameter in the solar cell characteristic is open circuit voltage,
(Voc). This can be seen at the crossing of the I(V) curve with the voltage axis.
Applying the open circuit condition, I=0, to the I(V) equation (3.1) as follows:
The open circuit voltage is given by:
From the above equation, it can be seen than the value of the open circuit voltage depends,
logarithmically on the Isc/Io ratio. This means that under constant temperature the value of the
open circuit voltage scales logarithmically with the short circuit current which, in turn scales
linearly with the irradiance resulting in a logarithmic dependence of the open circuit voltage
with the irradiance. This is also an important result indicating that the effect of the irradiance
is much larger in the short circuit current than in the open circuit value.
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The open circuit voltage is independent of the cell area, which is an important result because,
regardless of the value of the cell area, the open circuit voltage is always the same under the
same illumination and temperature conditions.
Below simulation result will show the open circuit voltage and short circuit current under
difference irradiance value, namely 200,400,600,800 and 1000 W/m2.
Figure 3.4 I(V) plots of a solar cell under several irradiance values: 200, 400, 600, 800 and
1000 W/m2
The plots in figure are obtained and, using the cursor utility in Probe, The value of V oc and Isc
are measured. The result are shown in table 3.1
Irradiance (W/m2)
Short circuit current (A)
Open circuit voltage (V)
1000
4.34
0.567
800
3.47
0.561
600
2.60
0.554
400
1.73
0.543
200
0.86
0.525
Table 3.1 Short circuit current and open circuit voltage under various irradiance
3.2.3 Maximum Power Point (MPP)
The output power of a solar cell is the product of the output current delivered to the electric
load and the voltage across the cell. It is generally considered that a positive sign indicates
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power being delivered to the load and a negative sign indicates power being consumed by the
solar cell. The power at any point of the characteristic is given by:
The value of the power at the short circuit point and open circuit point is zero, because the
voltage is zero at short circuit point, where the current is zero at the open circuit point. There
is a positive power generated by the solar cell between these two points. It also happens that
there is a maximum of the power generated by a solar cell somewhere in between. This
happens at a point called the maximum power point (MPP) with the coordinates V=Vm and
I=Im. A relation between Vm and Im can be derived, taking into account that at the maximum
power point the derivative of the power is zero:
At the MPP,
It follows that,
which is a transcendent equation.
Using Pspice the coordinates of the MPP can be easily found plotting the IxV product as a
function of the applied voltage.
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Figure 3.5 Plot of the power values under different values of irradiances
Table 3.2 shows the values obtained using equation (3.8) compared to the values obtained
using Pspice. As can be seen the accuracy obtained by Pspice is related to the step in voltage
we have used, namely 0.01V. If more precision is required, a shorter simulation step should
be used.
Irradiance(W/m2)
(PSpice) (V)
from
Im (PSpice) (A)
Pmax (Pspice)
(W)
equation (3.8) V
1000
0.495
0.4895
4.07
2.01
800
0.485
0.4825
3.28
1.59
600
0.477
0.476
2.47
1.18
400
0.471
0.466
1.63
0.769
200
0.45
0.4485
0.820
0.37
Table 3.2 Pspice result for several irradiance values
3.2.4 Fill Factor (FF) and Power Conversion Efficiency
A parameter called fill factor (FF) is defined as the ratio between the maximum power Pmax
and the Isc Voc product:
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The fill factor has no units. Indicating how far the product Isc Voc is from the power delivered
by the solar cell.
The fill factor can be greatly affected by the series resistance. Below is the normalized value
of the series resistance. The normalization factor is the ratio of the open-circuit voltage to the
short-circuit current.
Below equation shows the relationship between fill factor and series resistance.
Below simulation is done with the various values of series resistance, 0.0001, 0.001, 0.002,
0.005, 0.01, 0.02ohm.
Figure 3.6 Series resistance effects on fill factor
From the above simulation, the values of maximum power point and fill factors are calculated
and given in table (3.3)
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Series Resistance (Rs)
Maximum power (Pm)
FF
0.0001
2.02
0.82
0.001
2.004
0.814
0.002
1.98
0.8
0.005
1.93
0.78
0.01
1.85
0.75
0.02
1.689
0.686
Table 3.3 Series resistance and its affect on the fill factor
The power conversion efficiency
is defined as the solar cell output power and the solar
power inputting the solar cell surface, Pin. This input power equals the irradiance multiplied
by the cell area.
From equation (3.10), the values of efficiency of a solar cell are proportional to the value of
the three main photovoltaic parameters: (1) the open circuit voltage, (2) the short circuit
current density (3) fill factor, for a given irradiance G.
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Chapter 4
Generalized model of a solar cell
We had described an ideal behaviour of a solar cell based on an ideal diode and an ideal
current source in previous chapter. Ideal model is sometimes insufficient to accurately
represent the maximum power delivered by the solar cell. There are various effects which
have not been taken into account and that may change the solar cell response.
4.1 Series resistance
One of the main limitations of the model comes from the series resistive losses which are
presenting practical solar cells. In fact, the current generated in the solar cell volume travels
to the contacts through resistive semiconductor material, both, in the base region, not heavily
doped in general, and in the emitter region, which although heavily doped, is narrow. Besides
these two components, the resistance of the metal grid, contacts and current collecting bus
also contribute to the total series resistive losses. It is common practice to assume that these
series losses can be represented by a lumped resistor, Rs, called the series resistance of the
solar cell. The simulation results in Figure shows that several values of the series resistance at
a high and constant shunt resistance and at equivalent values of the irradiance and the
temperature.
Figure 4.1 Series resistance effects, I(V) characteristic for series resistance values from 1
ohm (bottom graph), 0.1, 0.01, 0.001, 0.0001 ohm (top graph)
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From the above figure, large differences are observed in the I(V) characteristic as the value of
series resistance increases, in particular the values of short-circuit current and of the fill factor
can be severely reduced. This is clearly seen in the several plots in figure where he value of
the short-circuit current remains sensibly constant, provided that value for the series
resistance equal to or smaller than 0.01ohm are used. For the open-circuit voltage can see
clearly from the plot is independent of the series resistance value as all curves cross at the
same point on the voltage axis and this is true regardless of the value of the shunt resistance,
and the values of the parameters of the recombination diode.
4.2 Shunt resistance
Solar cell technology in industry is the result of mass production of devices generally made
out of large area wafers, or of large area thin film material. A number of shunt resistive losses
are identified, such as localized shorts at the emitter layer of perimeter hunts along cell
borders are among the most common. This is represented generally by a lumped resistor, Rsh,
in parallel with the intrinsic device. The shunt resistance also degrades the performance of the
solar cell. The simulation result shown in figure
Figure 4.2 Effects of the shunt resistance on the I(V) characteristic
From the figure, open circuit voltage is only very slightly modified unless the parallel
resistance takes very small values. For the short circuit current, all plots cross at the same
point. Small values of the shunt resistance also heavily degrade the fill factor.
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4.3 Recombination
Recombination at the space charge region of solar cells explains non-ohmic current paths in
parallel with the intrinsic solar cell. This is relevant at low voltage bias and can be
represented in an equivalent circuit by a second diode term as in figure 4.3 with a saturation
density current J02, which is different from the saturation density current of the ideal solar
cell diode, and a given ideality diode factor different to 1, it is most often assumed to equal
2.This can be added to the solar cell sub circuit by simply adding a second diode 'diode2'with
n=2 in the description of the diode model, as follows:
.model diode2d(is=<j02*area>,n=2
(301)
Rs
(303)
(302)
IL=girrad
D1
D2
(300)
Rsh
(300)
Figure 4.3 Subcircuit including two diodes and series and shunt resistors
The open circuit voltage is also degraded when the recombination diode becomes important.
This can be seen in figure where in order to isolate the recombination diode effect; a high
value of the parallel resistance and low value of the series resistance have been selected.
Figure 4.4 Effects of the recombination diode
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The result shows that when the recombination diode dominates the characteristic is also
heavily degraded, both in the open-circuit voltage and in the FF. The short-circuit current
remains constant.
4.4 Temperature Effects
Operating temperature has a strong effect on the electrical response of solar cell. Taking into
account that in, terrestrial applications, solar cells can easily warm up o 60-65 degree Celsius
and that in space or satellite applications temperatures can be even higher, it follows that a
proper modelling of the temperature coefficients of the main electrical parameters is
mandatory. Temperature effects in solar cell can be included in Pspice model using the built
in parameters of the diode model included in the equivalent circuit. Namely the saturation
density current of a diode has a strong dependence on temperature and it is usually given by:
Where B is a constant independent of the temperature and XTI is a Pspice parameter also
independent of the temperature. Increase in temperature reduces the band gap of a
semiconductor, thereby effecting most of the semiconductor material parameters. The
decrease in the band gap of a semiconductor with increasing temperature can be viewed as
increasing the energy of the electrons in the material. Lower energy is therefore needed to
break the bond. In the bond model of a semiconductor band gap, reduction in the bond energy
also reduces the band gap. Therefore, increasing the temperature reduces the band gap. In a
solar cell, while increasing temperature reduces the magnitude of the exponent in the
characteristic equation, the value of diode reverses saturation current I0 increases in
proportion to expT, and the parameter most affected by an increase in temperature is the
open-circuit voltage.
We have simplified the solar cell model setting J02 = 0, the series resistance has been set to a
very small value and the shunt resistance to a large value so as not to obscure the temperature
effects.
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Figure 4.5 Effects of temperature
4.5 Effects of space radiation
The main effect of space radiation concerns the minority carrier lifetime degradation in the
semiconductor bulk leading to an increase of the dark current density, and also a degradation
of the photocurrent generated. Altogether these effects produce a significant reduction of the
maximum power of the solar cell. Simulation results using different space radiation fluencies
shown in figure
Figure 4.6 Degradation of the characteristic of the silicon solar cell for various space
radiation fluencies
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Chapter 5
Solar Cell in series and parallel and comparison
Single solar cells have a limited potential to provide power at high voltage levels because the
open circuit voltage is independent of the solar cell area and is limited by the semiconductor
properties. In most photovoltaic applications, voltages are greater than some tens of volts are
required and, even for conventional electronics; a minimum of around one volt is common
nowadays. It is then mandatory to connect solar cells in series in order to scale-up the voltage
produced by a PV generator.
PV application range from a few watts in portable applications to megawatts in PV plants, so
it is not only required to scale up the voltage but also the current, because the maximum solar
cell area is also limited due o manufacturing and assembly procedures. This means that
parallel connection of PV cells and modules is the most commonly used approach to suit the
output current of a given PV installation, taking into account all the system components and
losses.
5.1 Series connection of two solar cells
The figure shows the circuit corresponding to the series association of two solar cells. A
number of cases can be distinguished, depending on the irradiance levels or internal
parameter values of the different cells.
(43)
(42)
(302)
+
Xcell1
(303)
Subcircuit
Virrad 1
CELL_2.LIB
(300)
+
(45)
(44)
+
(302)
Virrad 2
Xcell2
Xcell2
Vbias
(303)
Subcircuit
Subcircuit
Cell2.LIB
CELL_2.LIB
(300)
(0)
Figure 5.1 Two solar cells in series
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Below is the simulation result done by two solar cells have same irradiance value and equal
values of the series and shunt resistances.
Figure 5.2 Simulation result of two identical solar cells in series
Figure 5.3 Comparison between one cell and two identical solar cells in series
From the above comparison curve, The I(V) characteristic has the same value as the short
circuit current of any of the two solar cells and that the total voltage drop is twice as the
voltage drop in single solar cell
Under normal operation, the two solar cells are connected in series but the irradiance they
receive is not the same. Below is the simulation of two series cell received different
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illumination. Cell number 1 received an irradiance of 1000 W/m2 and cell number 2 received
700 W/m2.
Figure 5.4 I(V) Characteristic of two solar cells in series under different irradiance values of
cells
From the figure 5.4, the association of the two solar cells, as could be expected by the series
association, generates a short circuit current equal to the short circuit current generated by the
less illuminated solar cell.
Figure 5.5 Voltages drop of the two cells under different irradiance
From the graph, we can see that the voltage drop in the two cells is spilt unevenly for
operating points at voltages smaller than the open circuit voltage. As can be seen from figure
5.5, at short circuit, the voltage drop in cell number 1 is 533 mV whereas the drop in cell
number 2 is -533 mV ensuring that the total voltage across the association is zero. This means
that under certain operating conditions one of the solar cells, the less illuminated, may be
under reverse bias. This has relevant consequences, as can be seen by plotting not only the
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power delivered by the two solar cell series string, but also the power delivered individually
by each solar cell as shown in figure 5.6.
Figure 5.6 Power delivered (positive) or consumed (negative) on the two solar cells unevenly
illuminated
From the simulation result shown in figure 5.6, the power delivered by solar cell number 2,
which is the less irradiance (lower solar current) may be negative if the total association work
at an operating point blow some 0.5 V. This indicates that some of the power produced by
solar cell number 1 is dissipated by solar cell number 2 thereby reducing the available output
power and increasing the temperature locally at cell number 2.
This effect is called the ‘hot spot’ problem, which may be important in PV modules where
only one of the series string of solar cells is less illuminated and which then has to dissipate
some of the power generated by the rest of the cells.
5.2 Shunt (Parallel) connection of Solar Cells
By connecting the solar cell in series, it will scale up the voltage. On the other hand, if PV
module needs to scale up the current, we need to connect the solar cells in parallel of a given
area or increasing the solar cell area. Such is the case in large arrays of solar cells for outerspace applications or for terrestrial PV modules and plants. For the parallel connection, we
need to connect node (300) and (303) directly in between two cells shown in figure 5.1.
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Figure 5.7 Two solar cells in parallel with different irradiance
The graph shows that the short circuit current is the addition of the two short circuit currents.
5.2.1 Shadow effects
The above analysis should not lead to the conclusion that the output power generated by a
parallel string of two solar cells illuminated a intensity of 50% of total irradiance is exactly
the same as the power generated by just one solar cell illuminated by the full irradiance. This
is due to the power losses by series and shunt resistance. Below simulation graphs will
illustrate this shadow effect.
CASE A: the two solar cells are half shadowed receiving and irradiance of 500 W/m2.
Figure 5.8 Two parallel cells under shadowed (CASE A)
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CASE B: One of the cell receiving full irradiance 1000 W/m2 and the other is completed
shadowed 0 W/m2.
Figure 5.9 One cell at full irradiance and the other at completely shadowed (CASE B)
CASE C: One of the cell receiving full irradiance 1000 W/m2 and the other is partially
shadowed at 200 W/m2
Figure 5.10 One cell at full irradiance and the other at partially shadowed (CASE C)
From the result of above three cases, it can be seen that neither the open circuit voltage nor
the maximum power are the same. Therefore, the assumption of a shadowed solar cell can be
simply eliminated does not produce accurate results because the associated losses to the
parasitic resistance are not known.
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5.4 The Terrestrial PV module
In this project, we will simulate the PV module as introduction. However, we will not test
simulations on other effects of PV module.
The most common photovoltaic module is a particular case of a series string of solar cells. In
terrestrial applications the PV standard modules are composed of a number of solar cells
connected in series. The number is usually 33 to 36 but various associations are also available.
The connections between cells are made using metal stripes. The PV module characteristic is
the result of the voltage scaling of the I(V) characteristic of single solar cell. It would be easy
to link up series strings of individual cells in Pspice.
However, there are two main reasons why a more compact formulation of a PV module is
required. The first reason is that as the number of solar cells in series increases, so do the
number of nodes of the circuit. Educational and evaluation versions of Pspice do not allow
the simulation of a circuit with not more than 2 cells in connections. The second reason is that
as the scaling rules of current and voltage are known and hold in general, it is simpler and
more useful to develop a more compact model, which could be used, as a model for a single
PV module, and then scaled-u[ to build the model of a PV plant. Below equation (5.1) is the a
very compact expression of the I(V) characteristic of a PV module.
where subscript M stands for ‘Module’ and
stands for series resistance. The equation is useful
for hand calculations.
(401)
Rs M
(403)
(402)
IL=girrad
D1
(400)
Figure 5.11 Pspice model for the PV module subcircuit
The model described above is able to reproduce the whole standard AM1.5G I(V)
characteristic of a PV module from the values of the main PV magnitudes available for a
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commercial module: short circuit current, open circuit voltage, maximum power and the
number of solar cells connected. Below is the simulation of I(V) characteristic of PV module.
Figure 5.12 I(V) characteristic and output power of a PV module
The electrical characteristics of PV modules are rated at standard irradiance and temperature
conditions. The standard conditions for terrestrial application are 1000 W/m2 at 25 degree
Celsius.
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Chapter 6
Conclusion and Recommendation
6.1 Conclusion
In conclusion, the models that I created for solar cell and module in Pspice are very useful to
predict energy production. Various electrical characteristic of solar cell are learnt and
simulated under different circumstances like temperature and irradiance. Simulation on solar
cells in series and parallel will be useful to understand in practical applications. We will be
able to calculate how many solar cells are needed and how the connection according to the
application voltages and current needed. Lastly, PV module model will be a good simulation
to start on when the system becomes more complicated. Therefore, the research done on
simulation of photovoltaic using Pspice will be useful tools to predict the energy prediction as
the actual solar system is costly and not so practical.
6.2 Recommendation
Further research could be done to identify combination of series and parallel PV cells and
arrays for temperature and irradiance effects. Further research could be done as well on the
PV module and various effects on the PV module. It will be more complete simulation of the
PV module. Further research could be done on the performance impact of different types of
solar material. Finally, it is also suggested that the manufacturers provide either a complete
current-voltage curve or the value of the slope at the short circuit current Isc, at the reference
condition so that the parameters for modelling the panel performance can be determined.
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Chapter 7
Critical Review and Reflection
Before selection of topics for this final year project, I am very much interested to choose
something related to research on alternative energy or energy saving products or technology.
Eventually I selected the topic on Simulation of solar photovoltaic cells/modules.
Since the start of the project proposal, I had studied the PV cells and modules, solar cell
principles and semiconductor devices from internet and reference books. I also learned the
Pspice software as my new exposure to the software through internet and started practicing
using sample programs and codes.
Learning how to simulate using Pspice is good achievement throughout the project. Studying
of previous project report on simulation of solar photovoltaic using other software, simulink
and mathcad, make me understanding more on the topic. I had done well till the project
proposal. I had used both professional 9.1 and education version 16.3 of Pspice for the project.
I had encountered the professional software 9.1 cannot install on Window 7, 64 bit. I also
encountered the software bug during simulation. I had to remove the software and reinstall to
overcome this software bug.
After submission of project proposal, I had been delaying the progress. This is mainly due to
poor management of time and motivation. The motivation is greatly affected by the family and
finance problems. However, I had overcome this problem after meeting with supervisor and
his strong comment. This was not easy, as I had to take care of my mother who is suffering
from cancer relapse, work commitment to fulfil, focusing on this project was a difficult
journey.
During later part of the project, I had put in more efforts to complete my project and tasks that
my supervisor assigned me to do. I have learned how to plan, managing of time and review the
project as it develops, and being consciously aware of how much I have been developing my
skills.
Another very important key skill is the communication skills. During the project I have done
the initial report to present the project plans, project investigation, and the thesis to present
the simulation model and results. Finally, I need to present the project at the presentation day
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and thus the skill of being able to communicate effectively is developed in a number of
different ways.
 Focus on what is learning and how to learn it.
 Learn effectively in new situations and contexts.
 Be clear about strengths and weaknesses.
 Recognize and develop range of skills.
Overall, I have learned different skills throughout the project. Most importantly, I had learned
how to manage time.
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References
[1] Francisco M. González-Longatt, Model of Photovoltaic Module in Matlab
[2] David L. King, James K. Dudley, and William E. Boyson, Sandia National Laboratories,
A Simulation Program for Photovoltaic Cells, Modules, and Arrays
[3] Krisztina Leban, Ewen Ritchie, Aalborg University, Pontoppidanstræde 101, Aalborg,
Denmark, Selecting the Accurate Solar Panel Simulation Model
[4] R.K. Nema1, Savita Nema1, and Gayatri Agnihotri1, Computer Simulation Based Study
of Photovoltaic Cells/Modules and their Experimental Verification
[5] http://en.wikipedia.org/wiki/Solar_cell
[6] Pspice manual
[7] Luis Castaner and Santiago Silvestre, Modelling Photovoltaic Systems Using PSpice
[8] Tyson DenHerder, Design and simulation of photovoltaic system using simulink
[9] http://en.wikipedia.org/wiki/Photovoltaics
[10] Solar Power Industries (2008). ‘Solar Cell Applications’. Retrieved Jan 20th, 2009 from
http://www.solarpowerindustries.com/
[11] Photovoltaic Systems - Technologies and Applications (2009). ‘History of
Photovoltaics’ Retrieved March 16th, 2009, from
http://www.pvresources.com/en/history.php
[12] Solar Timeline, US department of Energy, ‘The History of Solar’ Retrieved Jan 10th,
2009, from http://www1.eere.energy.gov/solar/pdfs/solar_timeline.pdf
[13] S.M.Sze. (2001). ‘Semiconductor Devices Physics and Technology’, Second Edition.
Solar Cell (pp. 318-325). Wiley Press
[14] S.O.Kasap. (2006). ‘Principles of Electronic Materials and Devices’, Third Edition.
Solar Cells (pp. 551-563). McGraw Hill, New York
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Appendixes
Appendix A
Gantt chart
Main Task
Sub Task
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Appendix B
Solar cell Manufacturing
The most cost-effective solar cells are made of single crystal silicon. Silicon is the most
abundant element on earth except for oxygen. However, it is generally found in compound
form, and requires chemical reduction and purification prior to becoming suitable as the
starting material for single crystal growth. Solar cell manufacturing is divided into eight
major functional operations. A flow diagram of the process together with a brief description
is shown in Flowchart 2.5.
Flow chart: Solar cell Fabrication process
The first production unit is GROW. A number of techniques can be used to grow silicon in
single crystal form. The Floating Zone process and Czochralski method are the two of most
widely applied throughout industry. Here a seed crystal is rotated while being slowly around
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10 cm/hr, withdrawn from a crucible of molten boron doped silicon. A schematic of the
process is shown in below figure.
Figure: Schematic of Crystal Growing Techniques
The resultant cylindrical-shaped crystal with 8-12 cm diameter, 1 m long then passes through
production step CROP. The seed and tail ends of the crystal are removed, and it is machined
to a specified diameter, and then cut into shorter pieces. The billets are now ready for the
SLICE, where they are sliced into thin wafers. After chemical ETCH thinning and POLISH a
mirror-like surface, wafers are ready for JUNCTION formation. A junction is formed at high
temperature by diffusing phosphorous into the boron doped wafer. It is essential to the
photovoltaic phenomenon. The next production step is called METALLIZE. To collect the
electrical current, the solar cell backside is covered with a metal. Similarly, a thin grid to
minimize the cell area covered of collector wires is deposited on front surface. The electrons
are collected by the grid on the front surface and flow through an external resistor to the back
surface of the cell. To reduce the number of reflected photons, an anti-reflective coating, AR
COAT is applied to the top surface of the cell. This completes a full solar cell processing.
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Appendix C
Pspice Simulation Code
Chapter 3 code
1. I(V) characteristic of solar cell model
****************************************
*
CELL_1.CIR
*
****************************************
.include cell_1.lib
xcell1 0 31 32 cell_1 params:area=126.6 j0=1e-11 jsc=0.0343
vbias 31 0 dc 0
virrad 32 0 dc 1000
.plot dc i(vbias)
.probe
.dc vbias -0.1 0.6 0.01
.end
2. I(V) plots of a solar cell under several irradiance values: 200, 400, 600, 800 and
1000 W/m2
3. Plot of the power values under different values of irradiances
****************************************
*
IRRADIANCE.CIR
*
****************************************
.include cell_1.lib
xcell1 0 31 32 cell_1 params:area=126.6 j0=1e-11 jsc=0.0343
vbias 31 0 dc 0
.param IR=1
virrad 32 0 dc {IR}
.step param IR list 200 400 600 800 1000
.plot dc i(vbias)
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.probe
.dc vbias -0.1 0.6 0.01
.end
Chapter 4 code
1. Series resistance effects, I(V) characteristic for series resistance values from 1
ohm (bottom graph), 0.1, 0.01, 0.001, 0.0001 ohm (top graph)
****************************************
*
CELL_2.CIR
*
****************************************
.include cell_2.lib
xcell2 0 31 32 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs={RS} rsh=100000
.param RS=1
vbias 31 0 dc 0
virrad 32 0 dc 1000
.plot dc i(vbias)
.dc vbias -0.1 0.6 0.01
.step param RS list 0.0001 0.001 0.01 0.1 1
.probe
.end
2. Effects of the shunt resistance on the I(V) characteristic
*************************************
*
SHUNT.CIR
*
*************************************
.include cell_2.lib
xcell2 0 31 32 cell_2 params:area=126.6 j0=1e-11 j02=0
+ jsc=0.0343 rs=1e-6 rsh={RSH}
.param RSH=1
vbias 31 0 dc 0
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virrad 32 0 dc 1000
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.step param RSH list 10000 1000 100 10 1 0.1
.probe
.end
3. Effects of the recombination diode
*************************************
*
DIODE_REC.CIR
*
*************************************
.include cell_2.lib
xcell2 0 31 32 cell_2 params:area=126.6 j0=1e-11 j02={J02}
+ jsc=0.0343 rs=1e-6 rsh=1000
.param J02=1
vbias 31 0 dc 0
virrad 32 0 dc 1000
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.step param J02 list 1e-8 1e-7 1e-6 1e-5 1e-4
.probe
.end
4. Effects of temperature
*************************************
*
TEMP.CIR
*
*************************************
.include cell_3.lib
xcell3 0 31 32 cell_3 params:area=126.6 j0=1e-11 j02=0
+ jsc=0.0343 rs=1e-6 rsh=1000
vbias 31 0 dc 0
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virrad 32 0 dc 1000
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.temp 27 35 40 45 50 55 60
.probe
.end
5. Degradation of the characteristic of the silicon solar cell for various space
radiation fluencies
****************************************************
*
SPACE.CIR
*
****************************************************
.include cell_5.lib
xcell5 0 31 32 cell_5 params:area=8 temp=27 jscbol=0.0436
+ pmaxbol=0.0208 vocbol=0.608 f={F}
+ ki=5.26E-3 fi=3.02e13 kv=0.042 fv=2.99e12
vbias 31 0 dc 0
.param F=1
virrad 32 0 dc 1353; One sun AM0
.plot dc i(vbias)
.probe
.dc vbias 0 0.6 0.01
.step param F list 1e10 1e11 1e12 1e13 1e14 1e15 1e16
.end
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Chapter 5 code
1. Simulation result of two identical solar cells in series
****************************************
*
SERIES.CIR
*
****************************************
.include cell_2.lib
xcell1 45 43 42 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs=1e-3 rsh=100000
xcell2 0 45 44 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs=1e-3 rsh=100000
vbias 43 0 dc 0
virrad1 42 45 dc 1000
virrad2 44 0 dc 1000
.plot dc i(vbias)
.dc vbias 0 1.2 0.01
.probe
.end
2. I(V) Characteristic of two solar cells in series under different irradiance values of
cells
3. Cells voltage
4. Power delivered (positive) or consumed (negative) on the two solar cells unevenly
illuminated
****************************************
*
SERIES_diff_irra.CIR
*
****************************************
.include cell_2.lib
xcell1 45 43 42 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs=1e-3 rsh=100000
ENG499 Capstone Project
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xcell2 0 45 44 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs=1e-3 rsh=100000
vbias 43 0 dc 0
virrad1 42 45 dc 1000
virrad2 44 0 dc 700
.plot dc i(vbias)
.dc vbias 0 1.2 0.01
.probe
.end
5. Two solar cells in parallel with different irradiance
****************************************
*
SHUNT2.CIR
*
****************************************
.include cell_2.lib
xcell1 0 43 42 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs=1e-2 rsh=1000
xcell2 0 43 44 cell_2 params:area=126.6 j0=1e-11 j02=1E-9
+ jsc=0.0343 rs=1e-2 rsh=1000
vbias 43 0 dc 0
virrad1 42 0 dc 1000
virrad2 44 0 dc 700
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.probe
.end
6. Two parallel cells under shadowed (CASE A)
******************************************
*
EXAMPLE4_2.CIR
*
******************************************
ENG499 Capstone Project
Page 47
.include cell_2.lib
xcell1 0 43 42 cell_2 params:area=8 j0=1e-11 j02=0
+ jsc=0.0343 rs=0.5 rsh=100
xcell2 0 43 44 cell_2 params:area=8 j0=1e-11 j02=0
+ jsc=0.0343 rs=0.5 rsh=100
vbias 43 0 dc 0
virrad1 42 0 dc 500
virrad2 44 0 dc 500
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.probe
.end
7. Case B:
Shadow effect of irradiance of 1000W/m2
******************************************
*
EXAMPLE4_2B.CIR
*
******************************************
.include cell_2.lib
xcell1 0 43 42 cell_2 params:area=8 j0=1e-11 j02=0
+ jsc=0.0343 rs=0.5 rsh=100
xcell2 0 43 44 cell_2 params:area=8 j0=1e-11 j02=0
+ jsc=0.0343 rs=0.5 rsh=100
vbias 43 0 dc 0
virrad1 42 0 dc 1000
virrad2 44 0 dc 0
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.probe
.end
ENG499 Capstone Project
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8.
Case C:One cell receive full irradiance and another cell at 200 W/m2
******************************************
*
EXAMPLE4_2B.CIR
*
******************************************
.include cell_2.lib
xcell1 0 43 42 cell_2 params:area=8 j0=1e-11 j02=0
+ jsc=0.0343 rs=0.5 rsh=100
xcell2 0 43 44 cell_2 params:area=8 j0=1e-11 j02=0
+ jsc=0.0343 rs=0.5 rsh=100
vbias 43 0 dc 0
virrad1 42 0 dc 1000
virrad2 44 0 dc 200
.plot dc i(vbias)
.dc vbias 0 0.6 0.01
.probe
.end
9. I(V) characteristic and output power of a PV module
*******************************
*
MODULE_1.CIR
*
*******************************
.include module_1.lib
xmodule 0 43 42 module_1 params:ta=25,tr=25, iscmr=5, pmaxmr=85, vocmr=22.3,
+ ns=36, np=1, nd=1
vbias 43 0 dc 0
virrad 42 0 dc 1000
.dc vbias 0 23 0.1
.probe
.end
ENG499 Capstone Project
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