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Simulation of Photovoltaic System using
Matlab/Simulink
Senior Project II
Submitted to the Faculty of
Engineering and Information Technology at the
Arab American niversity ! "enin
In #artial fulfillment of
$achelor of Science degree
$y%
Naser Ayman Alshafei
Samah Tawfeeq
nder the su#ervision of%
Dr. Osama Omari
March &'()
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Arab American niversity !"enin
Faculty of Engineering and Information
Technology
Simulation of Photovoltaic System using
Matlab/Simulink
$y%
Naser Ayman Alshafei
Samah Tawfeeq
nder the su#ervision of%
Dr. Osama Omari
March &'()
I
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*eclarationI certify that this work contains no material which has been accepted
for the award of any other degree or diploma in my name, in any
ni!ersity or other tertiary instittion and, to the best of my knowledge and
belief, contains no material pre!iosly pblished or written by another
person, e"cept where de reference has been made.
Stdent#s signatres$
Naser Ayman Alshafei$ %%%%%.
Samah Tawfeeq$ %%%%%.
Sper!iser signatre
Dr. Osama Omari$ %%%%%.
II
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Table of +ontents,IST -F FI.ES00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000I1
,IST -F TA$,ES0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
,IST -F A$$E1IATI-2S000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001I
A$STA+T00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001II
+3APTE (% I2T-*+TI-2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000(
&.& 'A()*+OND.................................................................................................................&
&.- /OTO0O1TAI( 203 (411..............................................................................................&
&.5 0 (411 6OD41..............................................................................................................5
&.7 4884(TS O8 I++ADIAN(4 AND T464+AT+4 ON 0 (411S..........................................9
&.9 6A:I66 O;4+ OINT T+A()IN* 26T3.................................................................<
+3APTE &% P1 S4STEM E5IEME2TS000000000000000000000000000000000000000000000000000000000000000000000000('
-.& 0 S=ST46 D4SI*N +O(4D+4...................................................................................&>
-.- *+ID?(ONN4(T4D 0 S=ST46S....................................................................................&&
-.5 STAND?A1ON4 0 S=ST46S..........................................................................................&-
+3APTE 6% SIM,ATI-2 A2* ES,TS0000000000000 00000000000000 00000000000000 000000000000000 00000000000000 00000(6
5.& 0 (411 6OD41...........................................................................................................&5
5.- (ON(1SION.................................................................................................................-7
EFEE2+ES0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000&7
III
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,ist of Figures8igre &?&$ cross section of a silicon 0 cell......................................................................-
8igre &?-$ Single diode model of the 0 cell....................................................................5
8igre &?5$ 0? cr!es of a 0 cell at different Temperatre and Irradiances....................@
8igre &?7$ 0? cr!e of the 0 cell with 6...................................................................
8igre &?9$Impp?0mpp characteristics of the 0 cell...............................................................
8igre -?&$ maBor 0 systems components ......................................................................&>
8igre -?-$ grid?connected 2grid?forming3 0 system with battery backp ....................&&
8igre -?5$Stand?alone 0 system ...................................................................................&-
8igre 5?&$Simlink 0 cell modle ................................................................................ &-
8igre 5?-.&$I0 cr!e at 9>>)wCm- ................................................................................. &-
8igre 5?-.-$ I0 cr!e at &>>>)wCm- ............................................................................. &-
8igre 5?-.5$ I0 cr!e at ->>>)wCm- ............................................................................. &-
8igre 5?5.&$ I0 cr!e at -.&9 ) .................................................................................. &-
8igre 5?5.-$ I0 cr!e at 5-5.&9 ) .................................................................................. &-
8igre 5?5.5$ I0 cr!e at 57.&9 ) .................................................................................. &-
8igre 5?7.&$ 0 cr!e at 9>>)wCm- .............................................................................. ->8igre 5?7.-$ 0 cr!e at &>>>)wCm- ............................................................................ ->
8igre 5?7.5$ 0 cr!e at ->>>)wCm- ............................................................................ -&
8igre 5?9.&$ 0 cr!e at -.&9 ) .................................................................................. -&
8igre 5?9.-$ 0 cr!e at 5-5.&9 ) .................................................................................. --
8igre 5?9.5$ 0 cr!e at 57.&9 ) .................................................................................. --
I0
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,ist of TablesTable 5?&$ ST( constants !ales and their discriptions .....................&7
0
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,ist of Abbreviations0$ hoto!oltaic
D($ Direct (rrent
A($ Alternating (rrent
6$ 6a"imm ower oint
6T$ 6a"imm ower oint Tracking
0$ ltra!iolet
I*'T$ Inslated *ate 'ipolar Enction Transistor
6OS84T$ 6etal?O"ide 8ield 4ffect Transistor
ST($ Standard Test (ondition
0I
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Abstract
;ith the rapid growth of power, the se of solar energy in electric
power applications is gradally increasing. One of those applications are the
photo!oltaic cells.
This stdy discsses the operation of photo!oltaic cells. And their
crrent F !oltage characteristic cr!es. The non?linearity of those cr!es
implies the tiliGation of efficient ma"imm power point tracker. ;hich
tracks the ma"imm possible power at any instant of time.
The direct?crrent natre of the photo!oltaics reqires the se of
in!erter to obtain an alternating?crrent which is more sitable for power
transmission.
8inally a simlation is presented sing 6AT1A'CSimlink software,
to !isaliGe and !erify the beha!ior of the main photo!oltaic system
components.
0II
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+ha#ter (% Introduction
(0( $ackground
+ecent Increase on the demand of power has raised a lot of qestion
abot the a!ailability of non?renewable power resorces and their impact on
the en!ironment. This led scientists and engineers to search for more
sstainable, cleaner, en!ironment?friendly and cost effecti!e power sorces
H&.
Among all renewable energy sorces, solar power systems attract
more attention becase they pro!ide e"cellent opportnity to generate
electricity while green hose emissions are redced and also it e"hibits
many merits sch as cleanness, little maintenance and no noise H-.
hoto!oltaic 203 technology is prominent way for har!esting solar
energy. 'ecase electrical power can be prodced withot any transitional
states sch as heat or mechanical. In addition to the compactness and
portability of this technology.
In the ne"t section the basic bilding block of 0 systems, namely the
0 cell will be discssed.
(0& Photovoltaic 8P19 cell
A solar cell is basically a p?n Bnction fabricated in a thin wafer of
semicondctor H-. The Bnction is made of materials that allow for the
photo!oltaic 203 effect to happen.
The 0 effect is the basis of the con!ersion of light to electricity in
photo!oltaic cellH5, when light hits the 0 cell it gi!es away some of its
energy to nearby electrons. A bilt?in?potential barrier in the cell acts on
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these electrons to prodce a !oltage, which can be sed to dri!e a direct
crrent 2D(3 throgh a circit.
8igre &?& shows the cross section of a 0 cell. ;hen light hits the N?
type material 2e.g. Selenim3H-, it e"cites the electrons ths pro!iding a
crrent that is collected by a metallic grid placed across the 0 cell as
shown in the right side of figre &?&.
Figure (:(% cross section of a silicon P1 cell
Silicon wafers sed for prodcing high qality 0 cells are made from
mono?crystalline silicon which is pre silicon with niform crystalline
lattice. Opposed to mlti?crystalline silicon which is less niform. The
efficiency of the former is higher by -?5J H7.
It is worth to mention that the most impressi!e of 0 impro!ements
and applications lies within nanotechnology, which allowed scientists to
create a plastic spray?on 0 cell that can tiliGe the sn#s infrared, in!isible
rays.
'ecase the infrared spectrm is tiliGed, solar cells can generate
electricity e!en on a clody day. Similar to paint, this composite can be
simply sprayed onto almost any material to ser!e as portable electricity H9.
-
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0 cells are often groped in modles 2in series3 to increase their
otpt crrent. Se!eral modles also can be connected in parallelCseries to
form an array or so called string. The more power is reqired by the 0
system, more 0 panels 2arrays3 are connected to that system H7.
(06 P1 cell model
In order to nderstand the beha!ior of the 0 cell, scientists and
engineers ha!e de!eloped !arios models to conclde the 0oltage?crrent
characteristics of the 0 cells in different en!ironments and conditions.
The most widely sed mathematical model for a single 0 cell, is the
single diode model H@. As shown in figre &?- the single diode model
consists of a crrent sorce connected to a shnt diode and resistor 2+ sh3 and
a series resistor 2+ s3.
Figure (:&% Single diode model of the P1 cell
The otpt crrent of the 0 cell can be written as H@$
&?&3
;here$
? I is the otpt crrent of the solar cell,
? I L is the photocrrent.
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? I D is the diode crrent.
? I sh is the crrent in the shnt resistance.
I D is gi!en by$
&?-3
;here$
? I os is the satration crrent,
? q is the electronic charge,
? V is the terminal !oltage of the solar cell,
? R s is the series resistance,
? A is the ideality factor,
? K is 'oltGmann#s gas constant, and
? T is the Bnction temperatre in )el!in.
Ish can also be sbstitted by$
&?53
'y sbstitting eqations 2&?-3 and 2&?53 in eqation 2&?&3$
&?73
8inally I os is gi!en by$
&?93
;here$
? I or $ the satration crrent at Tr .
? Tr: +eference Temperatre
? Ego: band?gap for Silicon.
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The main conclsion from the pre!ios eqations is that the main
factors go!erning the power generated by the 0 cell are$ the amont of
light that the cell is e"posed to, and the operating temperatre 2)3 of the cell.
4"posre to light is referred to as Irradiance which is defined by the
ratio of power 2;att3 per area nit 2m-3.
(0; Effects of Irradiance and Tem#erature on P1 cells
As noticed in the pre!ios section the main factors contribting to the
crrent generated by the 0 cell are the temperatre and irradiance. This is
clearly illstrated in figre &?5.
The photo?generated crrent is directly proportional to the irradiance
le!el, so an increment in the irradiation leads to a higher photo?generated
crrent. 6oreo!er, the short circit crrent is directly proportional to the
photo?generated crrentK therefore it is directly proportional to the irradiance
H@.
;hen the operating point is not the short circit, in which no power is
generated, the photo?generated crrent is also the main factor in the 0
crrent H@.
It shold be noted that !oltage flctations de to change in
irradiance. (an be neglected in practice H@.
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Figure (:6% 1:P curves of a P1 cell at different Tem#erature and Irradiances
Temperatre howe!er ad!ersely contribtes to the 0 cell crrent.
This is de to the natre of Silicon ?N Bnction. And ths can be annoying
fact, since solar light contains high energy particles and ltra!iolet 203
radiations that can directly heat the 0 cell.
The natre of meteorological conditions and shading 2incldingclods3. 6akes it challenging to draw the ma"imm generated power by the
cell throgh the load. Ths it is reqired that the cell at certain !oltage that
enables it to draw its ma"imm power H
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(07 Ma
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Figure (:;% 1:P curve of the P1 cell =ith MPP
The first assmption is based on the shnt crrent as e"plained in
eqation &?5, this crrent is !ery small and can be neglected H. This will
simplify the calclations needed to effecti!ely control the otpt crrent of
the 0 cell 2array3.
Figure (:7% Im##:1m## characteristics of the P1 cell >?@
The second assmption is based on the Boint effect of irradiance and
temperatre on the 0 cell. To e"plain this obser!e figre &?7 which shows
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the relation between the 6 illstrated by the ble and green lines, and
both irradiance and temperatre represented by the arrows.
If the green lines are assmed to be absoltely !ertical, neglecting the
small de!iation in 06 de to irradiation change at a constant temperatre.
nder this assmption the ma"imm power point crrent I6 becomes
linearly proportional to the irradiation 4 according to the eqation H$
&?@3
;here k is a constant.
/ence, it can be generaliGed that the 6 is linearly related to the
irradiance at any gi!en temperatre.
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+ha#ter &% P1 System euirements
&0( P1 system design #rocedureThe first task in designing a 0 system is to estimate the system#s
load. This is achie!ed by defining the power demand of all loads, the
nmber of hors sed per day, and the operating !oltage H.
8rom the load ampere?hors and the gi!en operating !oltage for each
load, the power demand is calclated. /ence, the natre of the load 2D( or
A(3 dictates the design of the in!erter. In the e"treme case where the load is
prely D(, no in!erter is needed.
Some designs may reqire batteries, in order to maintain a consistent
power spply. In general 0 systems can be categoriGed into two distinct
classes based on the natre of the load they spply, namely? grid connected
0 systems and stand?alone 0 systems.
+egardless of their type, al 0 systems share common component, as
shown in figre -?&
Figure &:)% major P1 systems com#onents >B@
&>
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&0& .rid:+onnected P1 systems
*rid?connected photo!oltaic systems are composed of 0 arrays
connected to the grid throgh a power conditioning nit and are designed to
operate in parallel with the electric tility grid H.
There are two general types of grid?connected 0 systems, based on
their role$ systems that assist the operation of the tility grid dring day
time. And ha!e no battery backp. These systems are often referred to as
grid?spporting systems.
The other type of systems is one with battery backp. And can keep
the load operating partially or entirely dring a tility otage. These systems
are sometimes called grid?forming 0 power systems H.
Figure &:C% grid:connected 8grid:forming9 P1 system =ith battery backu# >B@
The key to a sccessfl operation of 0 systems is the in!erter,
thogh it is the most comple" component. This relation has led the
researchers to de!elop and impro!e solid state power de!ices sch as
I*'T#s, 6OS84TS, microprocessors and ;6 controllers. In order to
frther increase the reliability and sstainability of 0 system H.
&&
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&06 Stand:alone P1 Systems
Stand?alone photo!oltaic systems are sally a tility power alternate.
They generally inclde solar charging modles, storage batteries, and
controls or reglators H as shown in 8igre 5?5.
Figure &:?%Stand:alone P1 system >B@
In many stand?alone 0 systems, batteries are sed for energy storage
as they may accont for p to 7>J of the o!erall stand?alone 0 system cost
o!er its lifetime H&&.
So the design of stand?alone 0 systems emphasiGes on sitable
battery technology 2Nickel?(admim$ Ni?(d C Deep?cycle lead?acid
batteries3 H&&.
The o!erall cost of a stand?alone 0 system can be redced with
proper battery?charging control techniqes, which achie!e high battery state
of charge and lifetime, nder continosly !arying atmospheric conditions
H&&.
&-
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+ha#ter 6% Simulation and esults
60( P1 +ell Model
The 0 system shown in figre 5?&, has been modeled sing6atlabCSimlink, which offers a rich en!ironment for modeling power
systems in real?time.
The model consists of inpt constants i.e. Irradiance and temperatre.
The 0 sbsystem contains the eqations necessary to obtain the !oltage?
crrent cr!es of the 0 system.
The 0 sbsystem takes an inpt !oltage which refers to the open
circit !oltage of the 0 cell and calclates the 0 cell crrent
corresponding to the temperatre?irradiance inpts
Figure 6:B% P1 cell Simulink model
The otpt of this model can be !isaliGed dring the simlation
throgh two scopes. And the data obtained can then be transferred to 6atlab
workspace for frther analysis and processing.
The eqations for obtaining the otpt crrent are shown in the abo!e
Simlink 0 cell model.
&5
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These eqations are based on Standard Test (ondition parameters
ST( H, which are related to real world !ales. The description of these
parameters can be seen in table 5?&.
arameter Description 0ale nitShort circit crrent at ST( 5.-9 A
Irradiance at the ST( &>>> ;Cm-
Open circit !oltage at ST( 7- 0
Temperatre at the ST( -9M-.>>>5 nit?less
0oltage coefficient with respect to temperatre change ?>.>>7 nit?less
0oltage of 6 at ST( 57 0
Table 6:(% ST+ constants values and their discri#tions >?@f& 23 is described by the following eqation$
25?3
8nction 89 23 calclates the new ma"imm power point crrent, as
e"pressed in the following eqation$
&7
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25?&&3
This is the primary otpt of the 0 sbsystem block, the other otpt
is the initial !oltage which can be sed to pertrb the 6, is gi!en by the
eqation 5?@$
25?&-3
The simlation was e"ected nmeros times for different !ales of
temperatre and irradiance, in order to obtain the 0 cell characteristic
cr!es as e"plained in chapter &. The figres below show the I0 and 0
cr!es of Irradiance and temperatres implemented in this simlation.
The otcome of the simlation sing the model described earlier can
be !isaliGed in the following figres.
8igres 5?-.&, 5?-.-, and 5?-.5 show the otpt I0 cr!es for the 0 cell
modle for a gi!en temperatre 2-.&9 )3 with Irradiances of 9>> )wCm-,
&>>>)wCm-, and ->>>)wCm- respecti!ely.
Figure 6:&0(% I1 +urve at 7''D=/m&
&9
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Figure 6:&0&% I1 +urve at ('''D=/m&
Figure 6:&06% I1 +urve at &''' D=/m&
&@
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8igres 5?5.&, 5?5.-, and 5?5.5 show the otpt I0 cr!es for the 0 cell
modle for a gi!en Irradiance 2&>>> )wCm-3 with temperatres of -.&9),
5-5.&9), and 57.&9) respecti!ely.
Figure 6:60(% I1 +urve at &B?0(7 D
Figure 6:60&% I1 +urve at 6&60(7 D
&
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Figure 6:606% I1 +urve at 6;?0(7 D
As mentioned in chapter &, the simlation reslts agrees with data
from the literatre, and confirms the theoretical relationships between
meteorological conditions and the 0 cell I?0 cr!es.
The abo!e simlation was done nder the following cases$
? The temperatre was fi"ed and the Irradiance was !aried.? The Irradiance was fi"ed and the temperatre was !aried.
In the first case, the figres show that as the Irradiance increases, the !ale
of the otpt crrent increases significantly, while the !ale of the otpt
!oltage increases slightly. The opposite reslts are obtained when the
Irradiance decreases 2slight decrease in 0oltage and significant decrease in
crrent3.
The second case is when the irradiance is fi"ed and the temperatre is
!aried, it can be seen that the otpt !oltage decreases and therefore the
power, as the temperatre increase, and !ice !ersa.
&
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As seen in the simlation model the otpt crrent is mltiplied with
the inpt open circit !oltage, to calclate e power of the cell and ths 0?
cr!es can also be obtained sing the model as shown in figres 5?7 and 5?9,
respecti!ely.
8igres 5?7.&, 5?7.-, 5?7.5 below show the reslting 0 cr!e of the
model at a gi!en temperatre2-.&9)3, with !arying Irradiances 29>>
)wCm-, &>>> )wCm-, and ->>> )wCm-3 respecti!ely.
Figure 6:;0(% P1 +urve at 7''D=/m&
&
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Figure 6:;0&% P1 +urve at (''' D=/m&
Figure 6:;06% P1 +urve at &''' D=/m&
8igres 5?9.&, 5?9.-, 5?9.5 below show the reslting 0 cr!e of the
model at a gi!en Irradiance2&>>> )wCm-3, with !arying Temperatre
2-.&9), 5-5.&9), and 57.&9)3 respecti!ely.
->
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Figure 6:70(% P1 +urve at &B?0(7 D
Figure 6:70&% P1 +urve at 6&60(7 D
-&
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Figure 6:70&% P1 +urve at 6&60(7 D
It can be seen from the abo!e 0 figres that at a certain temperatre, and
with the !ariation of Irradiance at the cell model inptK the ma"imm power
point increases significantly as the Irradiance increases and !ice !ersa, while
the open circit !oltage increase slightly as the Irradiance increases, and !ice
!ersa.
--
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8igres 5?9.&, 5?9.-, and 5?9.5 show the 0 figres for the modle at a
certain irradiance2&>>> )wCm-3 while the temperatre is !ariedK it can be
shown that an increase in temperatre cases both the 6 and the open
circit !oltage to decrease, while a decrease in temperatre increases the
!ales of the 6 and open circit !oltage.
-5
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+onclusion
The principle modeling of photo!oltaic modle based on 6AT1A'
en!ironment with different solar irradiations is presented. The simlation
reslts re!ealed that, the higher the solar irradiance the higher the otpt of
the 0?I and ?0 cr!es, and the lower the irradiance the lower the power
otpt.
(on!ersely, when temperatre increases the 0 cell otpt power will
degrade. And ths the operation of the 0 cell is e"tremely dependent on the
meteorological conditions at which it operates.
This dependency reqires special control mechanism to reglate and
ma"imiGe the otpt power of the 0 cellCarray. This is achie!ed by sing
proper 6T techniqes. As was pre!iosly discssed.
-7
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eferences&. $auer .ottfried 30 Lecture Notes in Physics: Photovoltaic Solar Energy
onversion. Oldenbrg $ Springer /eidelberg, ->&9. 0ol. >&. IS'N &&. p. &5>. IS'N$ ?&-?5->5@?9.
&>. Ismail $aharuddin $in0 Design An" Develo%#ent o$ 3ni%olar SP4!
S*itching Pulses $or Single Phase (ull,&ri"ge Inverter A%%lication. s.l. $
ni!ersiti Sains 6alaysia, ->>.
&&. Novel -attery charging regulation syste# $or %hotovoltaic a%%lications.
Doutroulis E0 and DalaitGakis D0 s.l. $ I444, ->>7. I44 roceedings.?
4lectric ower Applications. 0ols. &9&, No. -, pp. &&?&