10. Ali Jasim, National Aerospace University “Kharkiv Aviation
Institute”, Postgraduate Student,
Yuri Shepetov, National Aerospace University “Kharkiv Aviation
Institute”, Associate Professor, Candidate of Science
The main factors affecting on value of maximum power
point photovoltaic model using a matlab/simulink
Abstract: A Matlab-Simulink based simulation study of photovoltaic (PV) cells
is carried out and presented in this paper. The study is helpful in results showed that
Maximum Power Point (MPP) strongly depends on sun irradiance, shunt resistance,
series resistance, temperature and ideal factor. These results might be used as a
guide for PV system users.
Keywords: PV model parameters, Solar Cell Model, MPP, Insolation, Ideal
Factor, Fill Factor, Power Conversion Efficiency (PCE), Matlab/Simulink.
1. Introduction
The development of new energy sources is continuously enhanced because of
the critical situation of the chemical industry fuels such as oil, gas and others. The
evolution of renewable energy over the past decade has surpassed all expectations.
Global installed capacity and production of all renewable technologies has increased
substantially, and supporting policies have continued to spread to more countries in
all regions of the world. In fact, the demand for solar energy has increased by 20% to
25% over the past 25 years [1]. The market for PV systems is growing worldwide. In
fact, nowadays, solar PV provides around 500 GW. Between 2015 and 2020 [1], grid
connected PV capacity reached 21 GW and was increasing at an annual average
rate of 77% [1]. By 2050, solar power is anticipated to become the world's largest
source of electricity, with solar photovoltaics and concentrated solar power
contributing 16 and 11 percent, respectively. In order to get benefit from the
application of PV systems, research activities are being conducted in an attempt to
gain further improvement in their cost, efficiency and reliability. With no pollutant
emission, Photovoltaic cells convert sunlight directly to electricity.

11. Typically, a PV cell generates a voltage around 0.5 to 0.8 volts depending on
the semiconductor and the built-up technology. There are several studies which
dedicated to calculate the MPP under various conditions using MatLab/ Simulink.
The focus of this paper is on solar cell modelling which is discussed in section two.
Section three presents the Model of the Solar PV Module. In section four,
Environmental parameter variation of PV Module is investigated. Essential PV
Module Parameter Variation of PV Module has been presented in section five.
Finally, conclusions are made in section six.
2. PV cell model
A solar cell basically is a p-n semiconductor junction. When exposed to light, a
DC current is generated. The generated current varies linearly with the solar
irradiance.
To understand its behavior, we used a well-known equivalent circuit of the
solar cell. It is called one diode model as displayed in Fig. 1. It consists of a photo
current, a diode, a parallel resistor (Rsh) expressing a leakage current, and a series
resistor (Rs) describing an internal resistance to the current flow [2-4]. The standard
equivalent circuit of the PV cell is shown in Fig. 1.
Fig. 1. Equivalent Circuit of a PV Cell
The basic equation that describes the (I-V) characteristics of the PV module is
given by the following equation:
(1)
Where:
Iph Photocurrent (A);
Id
Rs
V
+
Ipv
-
Isc
(Iph )
Rsh
Ish

12. IS Diode saturation current (A);
q Electron charge 1.6 10-19
C;
kB Boltzmann's constant 1.38 10-23
J/K;
T Cell’s temperature in Kelvin;
n Ideal factor;
Rsh Shunt resistance (Ohm);
Rs Series resistance (Ohm);
VPV Panel voltage (V).
As a result, the complete physical behavior of the PV cell is in relation with Iph,
Is, Rs and Rsh from one hand and with two environmental parameters as the
temperature and the solar radiation from the other hand.
When Rsh and RS =0, the model reduces to an ideal model [4]. However,
the ideal model is so simple to represent real system. Thus, we used the one diode
model in our calculations.
3. Model of the Solar PV Module
The mathematical model of the PV module current (I) in equation (1) is
developed by MatLab/Simulink as in Fig. 2. The effect of different parameters
including solar irradiance, cell temperature, internal resistance, identity factor, and
saturation current on the power-voltage and current-voltage characteristic curves of
solar module are studied in the following subsections using the model [2-4] in Fig. 3.
Fig. 2. Simulink model of the solar PV module current Ipv
Ipv
Vpv
PV panel
Ppv
T
G
Irradiance
(W/m2)
Temperure
[ K ]
25+273
s ps
ps s
ps s
Ramp
Electrical Reference
F(x) =0
Solver
Configuration
X 0.514
0.025
20.02
100
V
Ipv
Diode
Controlled Current
Source
Current Sensor
Variable Resistor
Voltage Sensor

13. 4. Environmental parameter variation of PV Module
4.1 Solar Radiation Variation (G)
Fixing all other parameters, we notice that the effect of radiation variation on
the characteristic curves of the solar modules in Fig. 3 (a) & Fig. 3 (b). The P-V and I-
V characteristic curves are plotted for solar irradiance equals 400, 600, 800 and
1000 W/m2
. The Fill Factor (FF) is defined as Eq. 2
MP MP
T SC OC
I VMPP
FF= =
P I V
. (2)
Where MPP is the power calculated at maximum current value IMP and
maximum voltage value VMP, and PT is the power calculated at short current value ISC
multiplied by open voltage VOC. We conclude from Fig. 3 that the PV cell current
and MPP are highly dependent on solar radiation. The Power Conversion Efficiency
(PCE) is the ratio of the electrical power output Pout can be taken to be MPP,
compared to the solar power input Pin into the PV cell defined as Eq. 3. The capacity
of PV cell can be estimated by knowing, Fill Factor (FF) and Power Conversion
Efficiency (PCE) [3].
out
in in
P MPP MPP
PCE= =
P P ACG
(3)
Where G is the solar intensity per square meter and AC is the area on which
solar radiation falls (m2
). When the irradiance increases the output current increases,
the open-circuit voltage increases slightly, and the short circuit current increases.
MPP increases also FF& PCE increases as irradiance increases. From the figures
we notice that MPP at standard irradiance 400 W/m equals 15.1 W and increased to
40.5 W at 1000 W/m . Thus, we conclude that as irradiance increases the output
power increases too.
4.2 PV Module Temperature Variation (T)
For a constant irradiation 1000 W/m , we can notice the effect of temperature
variation on the characteristic curves of PV module as shown in Fig. 4 (a) and (b).
The temperature is given values equal 25 C, 50 C, 75 C and 100 C realize that the
voltage is highly dependent on the temperature. When the cell temperature
increases, the ISC increases slightly, the VOC decreases and MPP decreases and FF&
PCE decrease too.

14. a) b)
Fig. 3. a) Current-Voltage characteristic of a cell under varied irradiance;
b) Power-Voltage characteristic of a cell under varied irradiance
a) b)
Fig. 4. a) Current-Voltage characteristic of a cell under varied temperature;
b) Power-Voltage characteristic of a cell under varied temperature
The MPP at the standard temperature 25° & irradiance 1000 W/m equals
39.9 W. As the temperature increases to 100° , the MPP decreases to 36.42 W.
5. Essential PV Module Parameter Variation of PV Module
5.1 Variations of Shunt Resistance (Rsh)
We can notice the effect of variation of Rsh on current-voltage and power-
voltage characteristic curves of PV module as shown in Fig. 5 (a) and (b).

15. a) b)
Fig. 5. a) Current-Voltage characteristic of a cell under varied Rsh;
b) Power-Voltage characteristic of a cell under varied Rsh
From the figures we notice that the small value of Rsh causes PV module
current to fall more steeply indicating higher power loss and low Fill Factor & PCE. As
shunt resistance to 20000 Ohm, the maximum output power increases to 41.52 W. This
result happens an output voltage of = 17.73 V and output current = 2.34 A. We also
observe the voltage at MPP doesn't change with changing the values of the shunt
resistance.
5.2 Variations of Series Resistance (Rs)
The effect of the variation of Rs on the characteristics of PV modules is shown
in Fig. 6 (a) and Fig. 6 (b). The value of RS assumed different values. From the
figures we notice that large values of RS cause PV module current and voltage to fall
more steeply indicating higher power loss and low fill factor & PCE.
a) b)
Fig. 6. a) Current-Voltage characteristic of a cell under varied Rs;
b) Power-Voltage characteristic of a cell under varied Rs

16. Thus, series resistance must be low, if we take it into consideration. The MPP
at series resistance 0.131 Ohm equals 39.9 W at the output voltage 17.21 V and the
output current 2.64 A. As the RS increase to 0.231 Ohm MPP decrease to 38.1 W at
the output voltage 17 V and output current 2.3 A. When series resistance increases
to 1 ohm, the MPP decreases to 13.83 W at an output voltage equals 15.54 V and
output current equals 0.89 A.
5.3 Variations of Ideal Factor (n)
With slight modifications Simulink model, the I-V and P-V characteristic with
the changing value of n shown in Fig. 8 (a) and Fig. 7 (b). From the figures we notice
that as the value of ideal factor increases, the value of the MPP, FF and PCE
decreases. Also, we notice that the open circuit voltage decrease while short circuit
current doesn't change as ideal factor decreases.
a) b)
Fig. 7. a) Power-Voltage characteristic of a cell under varied ideal factor.
b) Current-Voltage characteristic of a cell under varied ideal factor
5.4 Variations of Saturation Current (Is)
The model helps in expecting the behavior of the PV cell for different reverse
saturation currents of the diode. The curves in Fig. 8 (a) & (b). Is varies as shown in
Table 6 decreases from 2 10-6
A to 2 10-1
A.
From the figures, we notice that as the value of Is increases, the MPP, FF,
PCE and the open circuit voltage decreases, and the short circuit current doesn't
change.

17. a) b)
Fig. 8. b) Current-Voltage characteristic of a PV cell under varied Is;
b) Power-Voltage characteristic of a PV cell under varied Is
6. Conclusion
In this research, A Photovoltaic model is easy to be used MatLab/Simulink to
study the effect of different parameters on the performance of PV module including
solar irradiance, temperature, shunt and series resistances, ideal factor and
saturation current. The simulation used one diode model and parameters are taken
from Si PV cell manufactured by Siemens Corp. The results show that when the
irradiance increases the MPP, Vpv, Ipv, Voc, Isc and PCE increases but FF
decreases. The temperatures of the PV array increases that means MPP decreases,
the short circuit current increases slightly and the open circuit voltage decreases.
Also, we notice that shunt resistance must be larger to increase output power, Fill
Factor and PCE. Thus, small values of Rsh cause PV module current to fall more
steeply indicating higher power loss and low Fill Factor & PCE.
While small values of RS cause PV module current and voltage to higher
power and higher Fill Factor & PCE. Thus, to maximize the output power of the
module, the series resistance must be low. Moreover, MPP increase as Ideal factor
increases and saturation current increases. The results can be used as a guide for
the solar system users.
References:
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powereurope.org. Solar Power Europe (SPE), formerly known as EPIA –
European Photovoltaic Industry Association. Archived from the original on 9 June
2015. Retrieved 9 June 2015.

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