Engineering, Technology & Applied Science Research Vol. 7, No. 6, 2017, 2109-2112 2109  
 

www.etasr.com Hota et al. : A Standalone PV System with a Hybrid P&O MPPT Optimization Technique 

 

A Standalone PV System with a Hybrid P&O MPPT 
Optimization Technique 

 

Shubhakam Hota 
Department of Electrical 

Engineering, Centre for Advanced 
Post Graduate Studies, Biju Patnaik 

University of Technology, 
Odisha, India 

shubhakam143@gmail.com 

Manoj Kumar Sahu 
Department of Electrical  

Engineering, Centre for Advanced 
Post Graduate Studies, Biju Patnaik 

University of Technology, 
Odisha, India, 

manojsahu.bls@gmail.com 

J. M. Rao Malla 
Department of Electrical  

Engineering, Centre for Advanced 
Post Graduate Studies, Biju Patnaik 

University of Technology, 
Odisha, India, 

mallajagan@gmail.com 
 

 

Abstract—In this paper a maximum power point tracking 
(MPPT) design for a photovoltaic (PV) system using a hybrid 
optimization technique is proposed. For maximum power 
transfer, maximum harvestable power from a PV cell in a 
dynamically changing surrounding should be known. The 
proposed technique is compared with the conventional Perturb 
and Observe (P&O) technique. A comparative analysis of power-
voltage and current-voltage characteristics of a PV cell with and 
without the MPPT module when connected to the grid was 
performed in SIMULINK, to demonstrate the increment in the 
efficiency of the PV module after using the MPPT module. 

Keywords-maximum power point tracking; mppt; photo voltaic; 
perturb and observe; p&o; optimizaton 

I. INTRODUCTION 
A solar photo voltaic (PV) cell converts solar energy 

directly into electrical energy. The solar cell is fabricated with 
the use of semiconductor devices that produce voltage from 
solar irradiance. The efficiency of a solar cell is small as it 
converts 30%-40% of solar irradiance into electrical energy but 
the nature of the application provides obvious advantages. To 
overcome the efficiency problem, the Maximum Power Point 
Tracking (MPPT) technique is used, which increases the 
efficiency about 20% - 30%. A MPPT system is defined as an 
electronics device which guides the PV cell in a manner that all 
the power produced by the PV cell will be delivered to the 
load. Generally MPPT is used to transfer maximum power 
either with higher voltage & lower current or with lower 
voltage & higher current and MPPT is installed between the 
PV cell and the load. An appropriate MPPT algorithm is 
required to reach the MPP, as the MPP varies with the solar 
irradiance and cell temperature. MPPT algorithm gives the 
point where the actual power output of the PV cell reaches to 
its maximum value when the source impedance is equal to the 
load impedance. A boost converter is employed to the PV 
system which increases the output voltage. The boost converter 
matches the impedance by changing its duty cycle. A boost 
converter is connected between the PV cell and the load [1-2]. 
There are a number of MPPT techniques used for maximum 

power point tracking [3-4]. This paper considers the P&O 
(perturb and observe) algorithm and provides comparison with 
and without MPPT that demonstrates the improvement in 
efficiency. The block diagram of the proposed model is shown 
in Figure 1. It consists of a PV cell, the MPPT, the boost 
converter and the load. First the voltage and current are fed to 
the MPPT controller, and then the MPPT generates the 
required gate pulse to the boost converter, so as to maintain the 
output voltage across the load irrespective of temperature and 
solar irradiance. 

 
Fig. 1.  Block diagram of the P&O method. 

II. CHARACTERSTICS OF A PV SYSTEM 

A. Basic Characteristics of a PV Cell 
A solar cell is based on the photoelectric effect i.e., the 

ability of a matter to emit electrons when light falls on it. A 
solar PV cell is a PN junction diode. When the photo current 
(Iph) falls on the solar cell, the valance band electron (free 
electron) in the N-type semiconductor get energized and moves 
to the P-side to fill up the holes. So the holes moves opposite to 
the electron and treated as direction of current. If there is no 
load i.e. Rse=0, then a short circuit condition occurs that means 
the short circuit current Iph=Isc=Imax. So that net current Iph = 0. 
If a load is connected, then a voltage produces across the load 
i.e. (Vrse), which is the diode voltage and this voltage(Vrse), 
forwards bias the PN diode. So a diode current (Id) flows 
opposite to the photon current (Iph). So the net current is given 
as I=Iph=Id (always Id<Iph). If Rse=0, then Iph=0, and at this 
condition, the diode voltage is given as VD=Vmax=Voc. 



Engineering, Technology & Applied Science Research Vol. 7, No. 6, 2017, 2109-2112 2110  
 

www.etasr.com Hota et al. : A Standalone PV System with a Hybrid P&O MPPT Optimization Technique 

 

B. Equivalent Circuit of a PV Cell 
Photo voltaic cells have non-linear characteristics as the 

output power changes directly with the temperature of the PV 
cell and solar irradiance [6]. The equivalent circuit of a PV cell 
is a single diode model. Here Gallium arsenide is taken as the 
semiconductor material, which have the band gap energy=1.12. 
The equivalent circuit of a PV cell is shown in Figure 2. 

 
Fig. 2.  Equivalent circuit of a PV cell. 

The equivalent circuit consists of a diode, the photo current, 
the shunt field resistance and the series diode resistance. The 
net current is given as: 

shdph IIII      (1) 

The photo current is given as: 

  refopscroph TTKIII  1    (2) 
where, Iro=references irradiations=1000, Isc=short circuit 
current=3.8 amp, K1= current coefficient=22.2·10

-3, 
Top=operating temperature=25+273.15

oC, Tref=reference 
temperature=25+273.15oC.  

Diode current can be written as: 

exp 1 exp 1D Dd s s
opT

V V
I I I

kTV
q




  
                 
  

  

 























 1exp

op

D
s

kT

qV
I


 

 





















 
 1exp

op

se
s

kT

IRVq
I


 

 
e x p 1s es

T

q V I R
I

V
  

    
   

 

 
















 
 1

...
exp

ST

se
Psd

NCV

IRV
NII


 

So, 

exp 1
. .

se

S S
d s P

T

IRV
N N

I I N
V C

   
   

      
      

 (3) 

where: η=ideality factor=1.36, k=Boltzmann’s constant, 
q=charge in electron, C=number of cells=36, NS=NP=1, 
number of series and parallel paths.  

Reverse saturation current is given as 

3

1 1
* * exp *

gOP
S rs

ref OP ref

qET
I I

T T T k
 

      
     

      
(4) 

Where, reverse saturation current at operating temperature 
is given as 

1exp 









OP

OC

I

rs

kCT

qV
I SC



   (5) 

where: VOC=open circuit voltage=21.1 V and ISC=short circuit 
current=3.8 A. 

Now the shunt field current is given as 

sh

IRV
sh

R
I se

     (6) 

where V the output voltage, Rse the series field resistance, Rsh 
the shunt field resistance. Now putting the values of (2), (3) 
and (6) in (1), the net current of the PV cell can be obtained. 
Figures 3 and 4 show the I-V and P-V curve of PV cell with the 
temperature variation and change in solar irradiance.  

 

 
Fig. 3.  I-V curve of a PV cell without MPPT. 

 
Fig. 4.  P-V curve of PV cell without MPPT.  



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III. CHARACTERISTICS OF A BOOST CONVERTER 
A boost converter has an important role for MPPT. It 

maintains the output voltage of PV cell by changing its duty 
cycle [3, 7]. So voltage at which maximum power obtained is 
determined. The duty cycle of the boost converter is given as 

T

t
D ON  and the output voltage is given as 

D

V
V inout 


1

. 

If D=0 then Vout=Vin and if D=1 then Vout=  . So the value 
of duty cycle varies from 0 to 1. By adjusting the duty cycle, 
the output voltage as well as the output power can be adjusted. 
Figure 5 shows the basic boost converter circuit. The circuit 
contains an inductor, a capacitor, a diode, a switch (MOSFET/ 
IGBT) and the load. When the switch is ON, the 
MOSFET/IGBT is short circuited and the entire current goes 
through the path as shown in Figure 6. At this time the inductor 
is charging and the diode act as reverse biased, so the output 
circuit cut from the input circuit. When the switch is OFF, the 
MOSFET/IGBT is open circuited and the diode D1 is forward 
biased. Now the inductor discharges and the capacitor stores 
the charge. So a higher voltage (VIN+VL), minus a small 
voltage drop across the diode, appears across the load. After the 
initial start-up when the switch is OFF, capacitor discharges 
each time and the current across the load maintains as the same 
current. So the output voltage across the load is almost 
maintaining the steady voltage. Figure 7 shows the current path 
when the switch is OFF. 

 

 
Fig. 5.  Basic Boost Converter Circuit. 

 

 
Fig. 6.  Boost Converter Operation at Switch ON. 

 

 
Fig. 7.  Boost Converter Operation at Switch OFF. 

IV. P&O AND ITS APPLICATION IN MPPT DESIGN 
Due to the simple structure and convenience of the P&O 

method, it is generally used to track the maximum power [8-9]. 

It finds the maximum power point of PV cell by iteratively 
comparing and observing the generated power of the PV cell. 
In this algorithm, the maximum power point is obtained by 
changing the terminal voltage and output power of the PV 
cells. The terminal voltage and output power can change by 
adjusting the load. By comparing and observing the previous 
and current value of voltage and power, we can conclude on the 
maximum power point (Figure 8). 

 

 
Fig. 8.  The flow diagram of the P&O method. 

One disadvantage is that oscillation occurs near the 
maximum operating point [10]. The magnitude of oscillation 
determined from variation of the output voltage. From the 
Figure 9, starting point is point A, and a +ΔV voltage 
perturbation moves the operating point A to B, causing a power 
drop with steady weather condition. According to the P&O 
method the voltage will change -ΔV in the opposite direction to 
maintain the output power. If the sun irradiance increases, 
power curve moves from P1 to P2 and operating point moves 
from A to C. 

 

 
Fig. 9.  Separation diagram of MPP for P&O. 

V. SIMULATION RESULT 
In this paper, soft switching boost converter for PV system 

interface has been implemented to reduce ripples at input 



Engineering, Technology & Applied Science Research Vol. 7, No. 6, 2017, 2109-2112 2112  
 

www.etasr.com Hota et al. : A Standalone PV System with a Hybrid P&O MPPT Optimization Technique 

 

current and switching losses in the converter. Figure 10 
represents power vs voltage characteristics. As shown with an 
open circuit voltage of 1000 V and short circuit current of 47 A 
maximum power that can be tracked is 30 kW. From the I-V 
characteristic (Figure 11), it is clear that with an increase in 
voltage, initially current decreases gradually but there is a 
drastic decrease in current just after maximum power point.  
Results are shown in Table I. 

 

 
Fig. 10.  PV curve of P&O MPPT. 

 
Fig. 11.  I-V curve of P&O MPPT. 

TABLE I.  PERFOMANCE COMPARISON OF THE PROPOSED P&O MPPT 
METHOD FOR 1S1P CONFIGURATION 

Shading 
Pattern 

Maximum 
Power 

From PV 
Module 

(kW) 

Tracking 
Techniques 

Maximum 
Power 
(kW) 

Tracking 
Efficiency 

1S1P 32 
Without 
MPPT 

14 43.75 

1S1P 32 P&O 30 93.75 

VI. CONCLUSION 
The classical MPPT tracking method has been simulated 

showing the increased tracking ability of a stand-alone PV 
system with the P&O MPPT technique. The PV simulation 
system used in this paper is simulated in 
MATLAB/SIMULINK. The model of PV modules used in the 

simulation is established according to the electrical 
specifications of industrial PV modules. After accomplishing 
the model of PV modules, the models of DC-DC boost 
converter and MPPT systems are combined with it to complete 
the PV simulation system with the MPPT function. The 
accuracy and execution efficiency for the MPPT algorithm can 
then be simulated under different weather conditions. Under 
normal environmental condition maximum achievable power is 
30 kW. 

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