MODELLING THE EFFECT OF SOLAR IRRADIANCE ON THE PERFORMANCE OF PHOTOVOLTAIC SYSTEM IN MAIDUGURI., B.U Musa, Baba Salihu Umar, M Abdulkadir & J.Usman
International
Journal of Research and Development Studies
Volume
7, Number 2, 2016
ISSN:
2056 – 2121
MODELLING THE EFFECT OF
SOLAR IRRADIANCE ON THE PERFORMANCE OF PHOTOVOLTAIC SYSTEM IN MAIDUGURI.
1B.U
Musa, 2Baba Salihu Umar 3M Abdulkadir and 4J.Usman
1,3,4Dept.
of Electrical and Electronic University of Maiduguri, Borno State, Nigeria.
2Dept.
of Electrical and Electronic, Ramat Polytechnic Maiduguri, Borno State,
Nigeria.
ABSTRACT
This paper focuses in
characterizing two solar cell modules monocrystalline and polycrystalline
individually under actual sunshine condition. The performances of a
photovoltaic solar module under varying insolation and temperature in Maiduguri
has been studied the investigations were conducted under different climatic
condition from cloudy to dusty and to clear days. The study revealed that the
system performed most satisfactorily in clear days, on dusty and cloudy days
the power produce from
the photovoltaic modules turns out to be low thereby
resulting in the poor performance of the system. Similarly insolation variation
with local time indicates that higher irradiance was recorded between 1pm to
2pm daily in all the climatic conditions. However, for KC1 (250W) panel the
efficiency under actual sunshine condition is higher than that specified by the
manufacturer the difference between the two falls under the dispersion range of
78%. While for KC2 (250W) the efficiency observed is less than the stated efficiency
by the manufacturer. For both solar panels (KC1 and KC2) the Fill factor
observed in actual sunshine condition is the same with that stated by the
manufacturer. However, the result of simulation shows excellent correspondence
with the experimental result.
Keyword:
Modelling, Effect, Solar Irradiance and Photovoltaic
INTRODUCTION
Energy is a prime
requirement for the progress and development of any country. The availability
of cheap, clean and abundant supply of energy is an index of the standard of
living of any nation. Industrialization and explosion in population growth have
caused the demand for energy to arithmetically increase in both developing and
developed countries. Nigeria has large number of villages that lack electricity
supply. The possibility of connecting these villages to the National grid is
less due to the present economic recession and fall in price of crude oil to
less than $30 per barrel. Presently only 40% of the Nigerian population have
access to electricity and out of this only 10% are rural populace. Therefore,
the need for renewable energy sources and especially solar to power the rural
communities could not be over emphasized. Nigeria is endowed with abundance of
renewable and non-renewable energy resources. However, the National Energy
Supply is dependent on fossil fuels and firewood. Fossil fuels made up 94% of
exports from Nigeria in 2006 with only a small fraction of this available for
domestic use. "Only about 40% of households in Nigeria are connected to
the National Electricity grid. Provision of electricity is largely supplemented
by private producer or use of individual electricity generators powered with
fossil fuel for the privilege income groups. Over 90% businesses and companies
have private generators leading to high production cost (Omokaro 2008). The
present dependence on fossil fuel (petroleum) is not enough to meet the energy
needs of the country. Interest in renewable energy development and
dissemination in Nigeria is driven by, among others, the recent increase in oil
prices, unavailability of electricity to majority of the population as well as
high cost and energy losses associated with grid extension. The government had
made effort through her several power reform programs and policies to attract
private participation, thus encourage RE development. However, there are
hindrances, mainly due to the technical and financial barriers, that need to be
overcome for this to be a reality (Sambo, 2009). The series resistance of a
monocrystalline silicon solar cell, which is a lumped quantity, was found to
vary with number of parameters. Its value has also been found to vary with
solar insolation level for a particular day. The mean series resistance of the
cell for harmattan and cloudy days are very high compared to the value obtained
from the manufacturers I-V curves for
simulated conditions. The mean series
Modelling the Effect of
Solar Irradiance on the Performance of
Photovoltaic System in
Maiduguri.
resistance (Rs) value for
a clear day was also to be higher. The lead and cable resistance of the
measuring circuit can cause deviation from actual V-I curves, if it is not kept to a very low value.
The
Experimental Method
An
experimental bed of 250 watt rating monocrystalline and polycrystalline solar
panels was installed at the premises of
power/machine laboratory, Ramat Polytechnic Maiduguri to measure the solar
irradiance, open circuit voltage and short circuit current for both panels at
an interval of 1hour daily. Simulink model was made using MATLAB to simulate
the effect of irradiance and temperature on single cell and output curves are
analysed to compare the models with the manufacturer's datasheets.
Figure 1 below, shows the schematic diagram of a solar
module and how the irradiance was received by the panels.
Irradiance
Figure1
Schematic diagram of Solar Modules under test
Modeling
of Solar Cell
The
equivalent electric circuit of a photovoltaic (PV) solar cell is a current
source in parallel with a diode as shown in figure 3.2. The output of the
current source is directly proportional to the radiation on the cell
(photocurrent) in joules. A current Id flows through the diode (D1).
The current (I) which flows to the load resistance.
Rs
ID I
Iph D1 Rsh V
Figure2 Single Diode of PV Module
Equivalent Circuit
Therefore,
the current flowing in the circuit is given by
I
= Iph – ID – Ish (1)
For
Shockley diode equations;
id – ID
(2)
(2)
Where;
V1=
KT
(3)
q
Applying
ohms law the current (Ish) becomes
Ish=
V + IRs (4)
Rsh
From
equation 2, 3 and 4 into equation (1) gives
I
= Iph- I0Exp
(V + IRs) – (V + IRs) (5)
nVi Rsh
International
Journal of Research and Development Studies
Volume
7, Number 2, 2016
Equation
(5) gives the general solar cell
characteristics
equation.
Where:
Iph is the photo generated current
Rs is the series resistance of the diode
Rsh is the shunt resistance of the diode
n is the ability or quality factor of the diode
The
complete behaviour of PV cells is described by the following model parameters
(Iph, n, Is, Rs, Rsh) which
represent the physical behaviour of PV module. These parameters are related to
insolation and temperature.
Two
parameters (n, I) are related to a diode model, the ideal value of quality
factors 'n' is unity but its practical value for silicon PV cells lies between
1 and 2. Similarly, shunt resistance (Rsh) in parallel with the
diode corresponds to the leakage current to the ground, in an ideal cell Rs
= Rsh = 0.
Environmental
Parameters Variation
The
two environmental conditions of solar Insolation and temperaturedetermine the
output of a solar cell at constant temperature. The photo generated current Iph
is directly proportional to solar Insolation the rated short-circuit current of
a PV specimen under standard test condition (STC) of 1000, Insolation and a
temperature of 25°C [9]: the effect of Varying
Insolation can be given as follows:
Iph (Isc K1 (T – 298) _6_ (6)
100
Where;
KI
is the cell short-circuit temperature coefficient given by 0.0017A/°C
T is normal operating temperature.
PV
Cell under Varying Temperature
The
effect of varying temperature on PV cell output is in two fold viz;
i. It affects the short-circuit current I of
cell as
given
by equation 6 and
ii.
It changes in saturation current of the diode in
PV
cell approximately as a cubic power.
Is
(T) Is
(7)
(7)
Where;
Vg— Eg is band gap energy of the semiconductor (1227)
V1 is the thermal voltage at room
temperature KT
q
Tnom= 273°K
Obviously
from equation 3.9, the saturation current of the diode or PV cell is temperature
dependent and as it increases with increasing temperature.
Pv
Module And Array Characteristics
A
solar photovoltaic module is a series collection of solar cells so as to
produce a desired voltage level. To model a photovoltaic module, the voltage-current
relationship in equation 7 is modified by neglecting Rsand Rsh.
I
= npIph – np.Is
(8)
(8)
Where:
n =is tile
number of cells connected in series.
Modelling the Effect of
Solar Irradiance on the Performance of
Photovoltaic System in
Maiduguri.
np= is tile path available for conducted of
current = I.
In a PV module there is
only one path available for current conduction since all cells are connected in
series.
SOLAR
CELL PEFORMANCE MEASUREMENTS
In
order to fully evaluate the performance of the solar panels the analysis have
been carried but under three different climatic conditions and variations of
open-circuit voltage and short- circuit current with insolation, temperature as
well as the variation of insolation with local time from hours of 8.30 a.m. to
5.30 p.m. under athese climatic conditions at different load resistance have
been presented in tables 1 to 2 below for KC1 (250W) and KC2 (250W) panels
respectively. The chapter presents various plots of the data obtained under
various climatic conditions. Similarly, this chapter presents results of Matlab
simulation of the PV module and general analysis of the results obtained.
EXPERIMENTAL
RESULTS
Below
are the various plots of the data obtained in the previous chapter, the plots
present variations of open-circuit voltages and short-circuit current
with temperature and insolation for the two solar panels, under different
climatic conditions.
Fig.
3 Variation of insolation with local time on clear days [21st April,
2015]
CLEAR DAYS
These
reading were taken in the middle of dry season (April) when there were no
clouds in the sky. Variations of insolation with different parameters has been
recorded and tabulated as shown in the tables below:
Table 1 Variation of insolation with local time on
clear days (11st April, 2015)
|
Local time (Hrs)
|
Insolation (KW/m2)
|
|
8:30 (am)
|
0.220
|
|
9:30 (am)
|
0.325
|
|
10:30 (am)
|
0.450
|
|
11:30 (am)
|
0.675
|
|
12:30(pm)
|
0.800
|
|
1:30 (pm)
|
0.850
|
|
2:30 (pm)
|
0.700
|
|
3:30(pm)
|
0.600
|
|
4:30 (pm)
|
0.350
|
|
5:30(pm)
|
0.150
|
International
Journal of Research and Development Studies
Volume
7, Number 2, 2016
MATLAB
SIMULATION RESULTS
The photon generated current Iph
is in fact related to insolation G (equation
8) at a constant temperature the photo generated current Iph
is directly proportional to solar insolation. The effect of varying solar
insolation on V-I characteristics can now be produced using Matlab where the
main variable parameter is insolation; the simulation is produced for five
different values of solar insolation from 0 to lOOOWm"2 in
steps of 250Wm"2. The standard parameters (Table 3) and (Table
4) of KC1 (250W) and KC(250 W) solar panel are considered for simulation, at a
constant temperature of 45°C. This is because a maximum normal operating
temperature of 45°C was recorded in Maiduguri.
Matlab Script File for variation in
insolation.
>>Isc=3.23;
% rated solar module Short-circuit current.
>> T=273+45; % Normal operating
cell temperature.
>>K=0.0017;
>>G=0:250:1000; %Variable
Irradiance.
>>Iph=(Isc+K*(T-298)*G/100;%
equation 3.8
>>plot(G,Iph),grid
>>Xlabel('Insolation Wm^2'),
label('photon generated current A)
ANALYSIS
OF RESULTS AND DISCUSSION
It can be seen from the graph that the
relationship between the independent variable, which is insolation G,
and the other dependent variables is mostly linear. That means the curve can be
approximated with a straight line of the form
y = mx + c
1
Where, y is the dependent variable (IKor
Voc), x is the independent variable (Insolation or
temperature) and m is the slope of the line and c is the
intercept on the ordinate axis. On the basis of this observation regression
techniques are used to fit the data in Table 1. The Matlab'spolyfitfunction,
which uses least squares regression, is used to fit the data. This result in
the following equation:
Vvoc = 2.2379G + 19.4472 2
Equation 4 relates the open-circuit voltage Voc and the available
insolation for KCI on clear days. Similarly, regression was carried using the
data in Table 2 This yield:
Voc = 2.1988G + 19.2082 3
21.5
21
20.5
20
19.5
19
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Insolation (KWm-2)
Fig. 4 Variation of Open
circuit voltage with insolation for KCI & KC2 on clear days
Various values of Voccan be
obtained from equations 4 and 5 respectively for various insolations. The two
equations can therefore be considered as empirical models for finding the
variations of open-circuit voltage with insolation for KCI and KC2 on clear
days in BirninKebbi. However, during
Modelling the Effect of
Solar Irradiance on the Performance of
Photovoltaic System in
Maiduguri.
harmattan season when the sky is mostly
overcast, the regressions for KCI and KC2 are found as follows:
For KCI
=Voc = 42.6431x +
4.7622 4
For KC2 =Voc = 42.7724x + 3.8065 5
For the two equations 4.6 and 4.7 the same
value of the slope was realized with a slight variation in the intercept and
this might be attributed to different design consideration for the two different
modules. Consequently, the characteristic of KCI and KC2 seem to be very similar
as can be seen in figure 5
17
16
15
14
13
12
11
10
9
8
7
0.05 0.1 0.15 0.2 0.25 0.3
Fig 5 Variation of open-circuit voltage with
Insolation for KC1 & KC2 on Harmattan days
The experimental results for the variation of
short-circuit current with insolation on clear days as seen from the graph
figure 5 as being more of a parabolic function. Which means the curve can be
approximated with a quadratic equation of the form
y = ax2+ bx + c 6
Therefore, regression carried out on the data
in
Table3 gives:
KC 1 =lsc
- -2.3321G2 + 3.6922G + 0.5268 7
KC 2= lsc = -0.7360G2
+ 2.3594G + 0.2603 8
The two equations (4.9 and 4.10) can be use
for finding the variation of short-circuits current
with insolation for the two solar modules in
Maiduguri.
2
1.8
1.6
1.4
 |
1.2
1
0.8
0.1 0.2 0.3
0.4 0.5 0.6 0.7 0.8 0.9
Insolation
(KWm-2)
Fig 6 Variation of Short-circuit current with
International
Journal of Research and Development Studies
Volume
7, Number 2, 2016
Insolation for KC1 & KC2 on cleardays
Figure 6 shows the relationship between
insolation and open-circuit voltage on cloudy days for KC 1 and KC 2 in
Maiduguri. From figure 4.42 it can be observe that the measured short-circuit
currents for both KC 1 and KC 2 follow similar pattern up to an insolation of
about 500Wm~2 from where there is slight variation in the magnitude
of short-circuit current, this can be said to be due to difference in
short-circuit current rating of the solar modules. However, the regressions
carried out on the data in Table 2 results to the following equations:
KC1 = 1,P
= 4.3072G -1.2019 9
KC2 = Isc = 3.7125G – 1.0200 10
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0.2
0.3 0.4 0.5 0.6 0.7
0.8 0.9
Insolation
(KWm-2)
Fig 7 Variation of Short-circuit current with Insolation for KC1 &
KC2 on cloudy
days
For open-circuit voltage and short-circuit
current variation with temperature on cloudy and harmattan days figures 6 and 7
respectively, the regression carried out on tables 1,2,3 and 5 results to the
following equations:
KC 1 Voc - -3.40007 +
104.3150
KC 2 Voc= - 3.8230 T + 112.1940
KC
1 Ioc= 0.0067T
+ 0.075
KC
2 Ioc = 0.0060T +
0.9070
For each of the solar panel,The maximum power
point, Fill factor, efficiency and optimum load were determine using equations
1 – 4 and various results are tabulated. The results computed and the standard
tables specified by the manufacturers
(KC 1 and KC2) are presented in Tables 2,3,4,
and 5 below.
Table 2 Observed/Standard Manufacturers Specification
for KC1 (250W Solar Module) Active
area-3990cm2, Weight-6.5Kg
|
Standard
Manufacturers
Specifications
|
Insolation
|
Temp
|
Vm
|
Im
|
Voc
|
Isc
|
|
(KW/m2)
|
(°C)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1
|
25
|
18V
|
3A
|
21.4V
|
3.23 A
|
|
Observed Experimental
|
0.850
|
42
|
17V
|
3.5 A
|
20.5V
|
I 3.80 A
|
|
Parameters
|
|
|
|
|
|
|
Modelling the Effect of
Solar Irradiance on the Performance of
Photovoltaic System in
Maiduguri.
For standard parameters of KC 1 the following
values were calculated;
Table 3 Calculated values of Observed/
Manufacturers Specification for KC1
|
Calculated
values For:
Manufacturers
Specifications
|
Max
power point
|
Fill
factor
|
Efficiency
|
Optimum
load
|
|
(W)
|
|
(%)
|
(Q)
|
|
|
250
|
0.78
|
1.4
|
6
|
|
|
Calculated
values For observed
|
250
|
0.77
|
1.8
|
4.86
|
|
Parameters
|
|
|
|
|
Table 4 Observed /Standard Manufacturers Specification for KC2 (250W Solar
Module) Active area= 5625cm2, Weight-7.5Kg
|
Standard
|
Insolation
|
Temp
|
Vm
|
In,
|
Voc
|
Isc
|
|
Manufacturers
|
(KW/m2)
|
(°C)
|
|
|
|
|
|
Specifications
|
|
|
|
|
|
|
|
|
1
|
25
|
18
|
4.83A
|
21.5V
|
5.03A
|
|
Observed
Experimental
|
0.850
|
42
|
17
|
3.6
|
20.3
|
3.85
|
|
Parameters
|
|
|
|
|
|
|
Table 5 Calculated values of Observed/ Manufacturers Specification for
KC 2
|
Calculated values
For:
Manufacturers Specifications
|
Max power point
|
Fill factor
|
Efficiency
|
Optimum load
|
|
(W)
|
|
(%)
|
(0)
|
|
|
250
|
0.8
|
14.91
|
3.73
|
|
|
Calculated values
For observed
Parameters
|
|
|
|
|
|
61
|
0.78
|
1.3
|
4.72
|
|
|
|
|
|
|
SUMMARY
The chapter has presented variations of
open-circuit voltage and short-circuits current for both KC1 and KC2 under
different weather conditions. Similarly, open-circuit voltage and short-circuit
current variation with temperature has been observed. Moreover, presented are
various plots from the observed results. Parameters such as fill-factor,
optimum load, efficiency etc. are also calculated for both KC 1 and KC 2
respectively so as to be compared with that specified by the manufacturer. Finally, mathematical modelling and Matlab
simulation of the solar module is
International
Journal of Research and Development Studies
Volume
7, Number 2, 2016
presented. The simulation result compared
with the experimental result show excellent correspondence to the model.
CONCLUSION
The study has investigated the performance of
a photovoltaic (PV) solar module under varying irradiance and temperature in
Maiduguri, a city in northern Nigeria. The study has been conducted at
different weather conditions. A simplified equivalent circuit of a PV cell has
been simulated using Matlab, the simulated results when compared with the
experimental results show good agreement and going through the dissertation, it
can be concluded that the following have been achieved.
n
Variation
of solar cell parameters
(current, voltage, etc)
with insolation and temperature has been studied.
n The effect of varying solar
radiation on a solar panel has been observed.
n An empirical model for
calculating variation of solar modules parameters (short-circuit current and
open-circuit voltage) with both insolation and temperature under three climatic conditions has been developed.
n Maximum efficiency and
maximum power of the two different solar cells modules
under investigation has been observed.
n Model of Photovoltaic solar
cell/module has been generated and simulated using Matlab.
n
Various
experimental results have been compared.
RECOMMENDATIONS
Base
on the findings of this project the following recommendations are made.
n
However,
in order to boost the power of the solar panel the light intensity can be
considerably increase by using a concentrating optics. A typical concentrator
system may use a light intensity 6-400 times the sun
[3]. Therefore, similar analysis should be carried out by in co-operating a
concentrator.
n
Base on the modeled equations a
Matlab/Simulink software or any relevant simulation software can be use to
simulate the system response for comparison purpose.
REFERENCE
Abdelkader,
M. R., Al-Salaymen, A., Al-Hamamre, Z. &Firas, F. S. (2010) ‘A Comparative
Analysis of the Performance of Monocrystalline and Multicrystalline PV Cells in
Semi Arid Climate Conditions: The Case of Jordan ISSN 1995-6665, 4(5) pp.
543-552.
Atia,
Y., Zahran, M. & Al-Hossain, A. (2010) ‘Solar Cell Curves Measurement Based
on Labview Microcontroller Interfacing’ Proceedings
of the 12th WSEAS International Conference on AUTOMATIC CONROL,
MODELLING & SIMULATION ISSN17.90-5117 ISBN978-92600-1-4.
Atiku,
A. T. (2005). "Characterization of monocrystalline solar cell under varying Climatic
conditions in Sokoto and environs".Proceedings of the conference
onApplication of photovoltaic Dan Fodio University Press.
Atiku,
A.T. &Sambo, A.S. (1990) "Experimental
Characterization of Photovoltaic Solar Cell" Nigerian Journal of Solar Energy, 9(4), pp. 85-87.
Bashir,
M. A., Ali, H. M., Khalil, S., Muzaffar, A. & Maryam, A. S. (2014)
Comparison of Performance Measurement of Photovoltaic Modules Winter Months
inTaxila, Pakistan. International Journal
of Photo energy 2(16) pp. 8-19.
Bukar,
A. L., Chee, W. T., Abubakar, M., Babangida, M., Jamilu, R. & Abdu, I.
(2014)
‘Economic
Assessment of PV/Diesel/Battery Hybrid Energy System for a non-electrified
remote villages in Nigeria’ International
Journal of Renewable Energy Research 2(14) pp 361-386.
Evaluation
of Photovoltaic Models Based on a Solar Model Tester’
Modelling the Effect of
Solar Irradiance on the Performance of
Photovoltaic System in
Maiduguri.
Gupta,
R.C. and Bajpai, S.C. (1987) "Electrical
characteristics of PV Generators" Journal of Solar Energy 4(21) pp. 165-169.
Komp,
R. J. (2001). "Practical
photovoltaic electricity from solar cell" 3rd edition.
Kulshreshtha,
D.C. (2006). "Electronic device
and circuits'' New age
international Publishers Ltd New Delhi, India.
Nwagbo,
E. E. &Gulma, M. A. (2009)."Sensitivity
Characterization of Phototransistor
OCP71 using Artificial Insolation" Nigerian journal of Solar Energy 2(9) pp.
109-116 http://Gaisma.mht
weather_com.mht "Hour
by Hour Weather Forecast for
Maiduguri Borno State.
Roger,
A.M. &Bube, J. H. (2004) "photovoltaic
system engineering" 2nd edition.New age international Publishers Ltd New Delhi, India.
Salih,
M. S., Firas, F. S., Hassan, M. L. &Bedaiawei, M. Y. (2012) ‘Performance
Evaluation of Photovoltaic Models Based on a Solar Model Tester’ International Journal of Information
Technology and Computer Science,7(1), pp.
17-120 http//:www.mecs-press.org Doi10.5815/ijtcs.2012.07.01.
Savita,
N., Nema, R. K. &Gayatri, A. (2011) "MATLAB/Simulink
based study of photovoltaic cells/array/modules and their experimental
verification"InternationalJournal
of Energy and Environmental8(19) pp. 487-500.
Skolis,
T. & Manuel, P. O. (2008) "Interconnection
Optimization with Renewable Power Source to Distribution Network" International Journal of Renewable Energy
Research 2(15) pp 167-201.
Sujod,
M. Z. (2010). "Design and
Installation of stand-alone Power System TrainingManual" Unpublished
Thesis, University of Malaysia, Pahang.
Walker,
G. (2001). "Evaluating MPPT
Converter Topologies Using a MATLAB PV Model" Journal of Electrical Electronics Engineering, Australia 21(1) pp. 49-56.
Partha,
S. & Paul, A.(2014) "Modelling combine effect of
temperature and irradiance on solar
cell parameters by
MATLAB/Simulink" 8th
InternationalConference on Electrical and Computer Engineering Dhaka,
Bangladesh.
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