Implementation of mppt algorithm on pv panel using pic16 f877 controller

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 06 | June-2015, Available @ http://www.ijret.org 60
IMPLEMENTATION OF MPPT ALGORITHM ON PV PANEL USING
PIC16F877 CONTROLLER
Shreyash Sharma1
, Maharshi Tikiwala2
, Ronak Dadhaniya3
1
IV year student, Department of Electrical Engineering, Chhotubhai Gopalbhai Patel Institute of Technology,
Gujarat, India
2
Gujarat, India
3
Gujarat, India
Abstract
This paper presents the design and practical implementation of a Boost-type power converter for Photovoltaic (PV) system for
energy storage application based on Perturb and Observe Maximum Power Point Tracking (MPPT) algorithm. A Boost
converter is used to regulate battery charging. The major drawbacks faced by the tracking algorithm in the conventional method
of tracking is overcome by the strategic utilization of a properly controlled and programmed design of Peripheral Interface
Controller which helps in achieving optimized output results of MPPT algorithm.. The system is controlled by a Peripheral
Interface Controller (PIC) 16F877 controller by sensing the solar panel voltage and generating the Pulse Width Modulation
(PWM) signal to control duty cycle of the boost converter. This type of microcontroller was chosen is best suited as it has the
necessary features for the proposed design such as built-in Analog-to-Digital Converter (ADC), PWM outputs, low power
consumption and low cost. Hardware results demonstrate the effectiveness and validity of the proposed system in order to attain
satisfactory results from the method. This paper mainly focuses on the effective utilization of PIC controller in the implementation
of the MPPT algorithm and its constructional features which help gain the appropriate and accurate results.
Keywords: Photovoltaic system, Analog-to-Digital Converter, Peripheral Interface Controller, Maximum Power Point
Tracking, Pulse Width Modulation, Boost-type power converter, Duty Cycle.
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1. INTRODUCTION
The major purpose of writing this paper is to obtain the
maximum power point of the connected PV panel with the
help of MPPT algorithm (Perturb & Observe method)
during the fluctuating conditions of solar temperature and
solar insolation. Perplexed conditions of solar insolation
make it difficult to obtain the perfect maximum power point
without the use of MPPT tracking device. In order to obtain
the accurate and optimum results of maximum power point
of the solar PV cell, the utilization of PIC controller
(PIC16F877) is made due to its simple constructional
features and easy installation with the other components of
the MPPT. Thus even with the use of Perturb and
Observation technique of MPPT we can obtain steady and
efficient results about maximum power point on the P-V
curve of the solar panel (6W). PIC controller due to its
operational properties helps obstructing the distorting nature
of perturb and observe algorithm and gives a pure and
precise result of maximum power points even in solar
fluctuating conditions. The basic aim is to charge the battery
of 12V and to utilize the battery’s energy to light a load,
now if this battery is connected to the solar cell through a
switch, then the power received by the battery will be a
multiple of peak current and battery voltage. Thus the power
received by the battery will be only 60-70% of the total
value and the rest 30% will remain un-utilized and in order
to fix this problem Pulse Width Modulation is used so that
no portion of energy remains un-used or un-utilized. The
surplus energy obtained as a result of PWM will be stored in
the controller and whenever the need arises, this energy will
be supplied to the load (Sonali Surawdhaniwar, 2012).
1.1 Basic Block Diagram of PV Cell
The main foundation of any solar panel starts from the
forming of a single solar cell, which are taken in appropriate
quantity and are connected in series-parallel fashion to form
the solar panel of rated values of voltage and current
(Solanki, 2014).
Before going into an in-depth analysis of the solar panel and
the actual MPPT structure and its operation, it is very much
important to know about the internal components of the
solar cell, in order to obtain a basic understanding for the
working of MPPT algorithm in the PIC controller in the
proposed system.
The basic definition is given as “Solar cell is a basic
fundamental element of a solar panel which performs the
function of converting solar energy into useful electrical
energy at standard values of solar insolation and
temperature” (Walker, 2006).

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The general block diagram of a solar PV cell includes the
following things (Solanki, 2014):
1.) Current Source.
2.) Shunt Resistance.
3.) Series Resistance.
4.) A Diode.
Fig-1: Equivalent diagram of solar PV cell
The above equivalent circuit diagram of solar PV cell
signifies that solar cell is a current generating device with a
diode connected in anti-parallel direction in order to resist
the back-flowing currents and provides protection to the
solar cell. Whereas the series resistance provides evidence
of contact resistance i.e. between metal contacts and Silicon
material, and shunt resistance provides the resistance due to
the power loss caused due to manufacturing defects in a PV
cell (Harjai, Bhardwaj, & Sandhibirgha, 2008).
The voltage that we get across the PV cell is known as the
PV cell voltage and that will increase with the increase of
cells connected in series, whereas the current can be
maximized by connecting PV cells in parallel fashion. By
this series-parallel combination we can obtain a solar panel
on which we track the maximum power point and utilize its
energy for power generation and other purposes (J.Surya
Kumari, 2012). The basic building block of any solar panel
depends on the series-parallel configuration of the individual
solar cells which decides its current, voltage, and power
ratings.
1.2 MPPT Structure and Working
Fig- 2: Basic Block Diagram of MPPT
The above block diagram shows the basic connection
diagram when the solar panels are connected to the MPPT
circuitry. Here after the voltage and current generated by the
solar panels are sensed by the appropriate sensors connected
in shunt to the panel and is fed to the microcontroller (here
PIC controller) in which the Perturb and Observe algorithm
sequence is embedded as a program. This controller verifies
whether the input voltage and current values are matching
with the reference values set by the user and according to
these values sends pulse signals to the PWM (Pulse Width
Modulator). PWM on receiving these signals provides
accurate triggering pulses for the power switch (MOSFET)
which in turn performs the operation of boosting the
voltage. Finally the output voltage is supplied to the load
connected in series with the converter.
1.3 Actual MPPT Block Diagram
It is quite obvious to predict that there are minor differences
between the theoretical and the actual or real time block
diagram of MPPT. These differences vary from application-
to-application and the type of features adopted with it. The
actual project block diagram in our case is shown below
which includes all the components as discussed in the
previous topics.
Fig- 3: Actual Block Diagram of MPPT
Here in this present diagram, solar panel is considered as a
battery, also there are two voltage regulators connected to
which a 5V supply is provided, so that the voltage level is
maintained and a proper voltage is given to the PIC
controller for its functioning. A 2*16 LCD is provided
across the microcontroller which provides with the real-time
data of the tracking voltage and current of the solar panel.
There are 3-4 LEDs used in the circuit to let know the user
about the proper functioning of MPPT device and if some
violation is found then the LED instantaneously lights ON
showing that some serious problem has occurred in the
circuit. There is a quartz crystal attached with the
microcontroller to generate 20MHz frequency for the
operational purpose of PIC controller. The batteries are

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connected in the circuit for the major purpose of taking the
boost voltage from the converter and get charged, acting as a
load in our case. This diagram gives the basic outline about
the modeling of project.
The model presented above is for the special application of
MPPT that operates in an autonomous mode with the PIC
controller connected in the circuit. Here it is possible to
connect a load with the battery, which can supply the power
stored in it to the load when required. Any type of lighting
load or a small rated motor can be connected here for
satisfying the load applications in the present MPPT system.
2. PV ARRAY CHARACTERISTICS
There are basically different types of characteristics
obtained from the PV module, which actually determines the
various aspects such as maximum power point, maximum
voltage, temperature relation with current-voltage, etc.
which gives us the correct idea about the information
obtained from the photovoltaic characteristics. Here we have
obtained the Power v/s Voltage, Power v/s Current and
Voltage v/s Current characteristics for the solar panel of 6
watts rating (11.5 volts, 0.61 ampere).
Fig -4: Power v/s Voltage Characteristics
The characteristic shown above is the power versus voltage
curve for a 6 watt panel at different sun values of
1000W/m2
, 800W/m2
and 600W/m2
. The above curve shows
that the panel operates efficiently and reaches the peak point
of 6W at a voltage of 10.46volts. If voltage is further
increased the n power will significantly drop down to lower
values. Same can be applied for sun values of 800W/m2
and
600W/m2
.
These characteristics are important from the point of view
that it helps us in determining the maximum power point
range of any given solar panel.
Fig -5: Current v/s Voltage Characteristics
The above characteristics show the current versus voltage
relationship of a 6 watt solar panel.
The different values of solar insolation help us to determine
the values of voltage when the current is varied. It can be
perfectly said from the graph that at the current value of
0.61 Amp we get a perfect value of voltage of 11.5 volts
according to the specifications given for the solar panel.
After reaching a certain value, the voltage starts to decrease
and reaches to a zero value for the value of sun =1000W/m2
.
These are similarly obtained for other values of sun of
800W/m2
and 600W/m2
.
2.1 Boost Converter: In-Depth Analysis
The major use of DC-DC boost-converter in MPPT is that it
improvises the voltage profile of the main system that comes
through the solar panel after passing through the MPPT
controller, so that an output voltage which is greater in value
as compared to the input solar panel voltage can be obtained
(Sonali Surawdhaniwar, 2012). Due to its effective duty
cycle ratio and efficient working when connected in series
with the solar panel, it is majorly utilized in this circuit.
Boost converter like buck converter works in two modes,
which defines the actual working that takes place in the
boost converter circuitry. In our boost converter application,
we have implemented MOSFET as our power switch in the
circuit due to its efficient power and voltage characteristics.
The switching time required for MOSFET is sufficient for
the operation of boost converter.
The two modes of boost-converter operation are defined as
below:

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2.1.1 Mode 1 Operation of Boost Converter
Fig- 5: Mode 1 Operation of boost converter
Fig.6 illustrates the circuit action during the initial high
period of the high frequency square wave applied to the
MOSFET gate at start up (Harjai, Bhardwaj, &
Sandhibirgha, 2008). During this time MOSFET conducts,
placing a short circuit from the right hand side of L1 to the
negative input supply terminal. Therefore a current flows
between the positive and negative supply terminals through
L1, which stores energy in its magnetic field. There is
virtually no current flowing in the remainder of the circuit as
the combination of D1, C1 and the load represent much
higher impedance than the path directly through the heavily
conducting MOSFET.
The other mode of boost converter is further explained in
further topic.
2.1.2 Mode 2 Operation of Boost Converter
Fig- 6: Mode 2 operation of boost converter
Fig. 7 shows the current path during the low period of the
switching square wave cycle. As the MOSFET is rapidly
turned off the sudden drop in current causes L1 to produce a
back e.m.f. in opposite polarity to the voltage across L1
during the on period, to keep current flowing (Harjai,
Bhardwaj, & Sandhibirgha, 2008). This results in two
voltages, the supply voltage VIN and the back e.m.f. (VL)
across L1 in series with each other. This higher voltage (VIN
+VL), now that there is no current path through the
MOSFET, forward biases D1. The resulting current through
D1 charges up C1 to VIN +VL minus the small forward
voltage drop across D1, and also supplies the load.
2.2 Brief Details about PIC16F877A Controller
The current recent trends in microcontroller are the usage of
more advanced microcontrollers in major applications. The
mostly utilized controller in majority of the applications is
the PIC controller, due to its advanced modeling and easy
installation. The PIC16F877A features 256 bytes of
EEPROM data memory, self -programming, an ICD, 2
Comparators, 8 channels of 10-bit Analog-to-Digital (A/D)
converter, 2 capture/compare/PWM functions, the
synchronous serial port can be configured as either 3-wire
Serial Peripheral Interface or the 2-wire Inter-Integrated
Circuit bus and a Universal Asynchronous Receiver
Transmitter (USART).
In this paper a brief introduction about PIC controller is
provided to get information about its implementation in the
main circuit. Only the major features which are mainly
required and utilized are described here. All of these
features make it ideal for more advanced level A/D
applications in automotive, industrial, appliances and
consumer applications.
PIC controller is utilized in our application so as to obtain
smooth results of maximum power from perturb and observe
technique algorithm.
Fig- 8: Pin diagram of PIC16F877 controller
Fig.8 given above gives us the basic idea about the PIC
controller circuit which contains 40pins to which various
input and output ports can be connected. This
microcontroller is used in the implementation of perturb and
observe algorithm in order to attain stable maximum power
point of the solar panel in a short time duration. PIC
controller because of its multi-operational parameters and
easy implementation in the circuit improves the fluctuating
nature of power v/s voltage curve of the 6W solar panel.

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2.3 Flowchart for Perturb AND Observe Technique
in Application with PIC Controller
Fig- 9: Flowchart for PWM generation (J.Surya Kumari,
2012)
The diagram above signifies the actual structure of
algorithm which is used for PWM generation in Perturb &
Observe algorithm. This algorithm program will first
configure all the accessories connected with it i.e. LCDs and
LEDs. Afterwards will introduce all the variables that are
necessary for the algorithm to run and then after a 1minute
delay will measure the panel voltage and panel current. If
the panel voltage that is accessed by the controller is greater
than 10.5V (set value) then the controller will decrement the
pulses given to the PWM and if the value is less than the
pre-set value then it will monitor the next condition. If the
panel voltage is checked in the next iteration is less than
10V then the controller gives signals to increment the PWM
and so PWM generation takes place. If the voltage is lower
than 10V then the algorithm starts again its monitoring from
the start by measuring the panel voltage and current. Here
the range of 10V to 10.5V in the algorithm is taken as per
the requirement of application. Any random value can be
taken and can be set as a pre-set value which becomes the
decisive function for the controller whether to generate
PWM or not. If the values are set at any other voltage values
say 15V to 15.5V then also the controller will generate
PWM only that this time it will generate pulses of different
magnitude as compared to the previous one. In this way it is
found that setting the values for PWM generation is quite
flexible in the operating ranges of the load in case of Perturb
& Observe technique of MPPT.
3. HARDWARE IMPLEMENTATION OF MPPT
ALGORITHM
Before performing the hardware implementation of MPPT
on a practical basis, there is a need to design the whole
hardware structure according to the practical design of
MPPT which is provided in the diagram given below:
Fig- 10: Circuit Diagram of MPPT Implementation

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By observing the circuit diagram we can say that the power
supply is derived from 12V DC battery in per unit. 3 pin
regulator gives 5V DC fixed voltage. The circuit works on
5V DC supply. The microcontroller works on 5V DC and its
crystal frequency is 20 MHz which is clock for our
microcontroller. We have used PIC16F877 as
microcontroller and so it has got 33 input/output pins, 8K
flash memory, 256 ram and 256 EEPROM and it has got
10bit built-in ADC (Analog-to-Digital Converter).We
measure the panel voltage from AD input connected on pin
2 of microcontroller. PWM output is of 100microseconds
(10kc)is given on pin 21 which drives bc547 which drives
MOSFET (IRFZ44), diode (5408) is used as a free-wheeling
diode in the circuit. 470 microfarad capacitors are used as
filters diode (4007) is used for blocking reverse current flow
that comes from the battery.
A 0.5ohm current sensing resistance is used for sensing
current and this operation of current sensing is done on pin
number 9 of the microcontroller. In our case the reference
voltage is 5V DC on pin number 5 of the microcontroller. If
the measured value of the panel voltage is greater than
10.5V DC then the microcontroller will increase the PWM
and if the measured value of the panel voltage is less than
10V DC then the microcontroller will decrease the PWM. In
this format almost all the time the maximum power range of
the solar panel is maintained. The connections for LCD is
done on the PORT B of the microcontroller and also the
LCD that is connected as an external accessory displays
panel voltage and panel current at all times.
Fig- 7: Hardware implementation of MPPT(with panel)
The images shown below are of the hardware
implementation of MPPT with solar panel connected as an
input to the hardware circuit. There is a battery of 12V (two
batteries of 6V in series) connected to the on-board MPPT
circuit implementation which is the load in our application.
The main working parameters in our application are the
temperature of 30̊ C with solar insolation of 1000W/m2
.
The image above is showing the solar panel as the input
given to the controlling circuit (including PIC controller,
PWM, boost converter, resistors and capacitors, LCDs and
LEDs, with timing circuit) and the control circuit after
generating maximum power by running the algorithm gives
the voltage supply to the battery which charges the battery
(here battery should be considered as load application). The
panel used here is of 20 W and the battery connected across
the controller output is of 12V (two 6V batteries) connected
in series with each other.
Fig- 8: Hardware Implementation of MPPT(without panel)
The upper two diagrams depicts the values of voltage (in
volts) and current (in milli-amperes). The LCD display of
2*16 shows the output values of voltage and current from
which we can evaluate the values of maximum power. The
value of voltage here fluctuates between 11.6V to 12V,
whereas the current varies in the ranges of 560mA to
600mA.
Whereas the lower two diagrams, depicts the tracking of
power at variable time interval with the values of voltage
varying in between 11.2V to 11.5V and the current ranging
from 560mA to 600mA; this signifies that the controller
after reaching the maximum power point, oscillates between
certain pre-determined values of voltage on the P-V curve of
the solar panel.
The value of maximum power is obtained after the
controller performs numerous oscillations around the peak
point.

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Fig- 13: Different values of voltage and current while
tracking the maximum power.
Fig- 14: Value of maximum power achieved after the
oscillations performed by the controller
The diagram shown above signifies that the maximum
power point tracking conditions that are required for our
conditions are fully satisfied and thus it is verified that with
the help of perturb and observe technique we can obtain the
required value of maximum power of the panel.
4. CONCLUSION
From the above performance of Perturb and Observe
algorithm it is clear that the MPPT power obtained after the
boost converter varies the voltage level, will result in the
power nearly as same as the power which is obtained from
the PV panel. This means that by controlling the PWM of
the boost converter, we have obtained the maximum power.
By using the PIC controller, the maximum power is
delivered by the panel and 12V battery is charged
respectively and results are obtained smoothly and
accurately.
REFERENCES
[1]. Geoff Walker, “Evaluating MPPT Converter
Topologies Using A MATLAB PV Model” , University of
Queensland, Australia, 2002.
[2]. ArjavHarjai, AbhishekBiswajit, and
MryutunjaySandhibirgha, “Evaluation of Maximum Power
Point Tracking Methods In Solar Photovoltaic Array,”
Project Report, National Institute of Rourkela, Orissa, 2008.
[3]. A. Dolara, R. Faranda, S. Leva. “Energy Comparison of
Seven MPPT Techniques for PV Systems”. Electromagnetic
Analysis & Applications, 2009, 3: pp-152-162.
[4]. BiswajitSethy, “Application Of Sliding Mode
Technology In PV Maximum Power Point Tracking Systems
“PhD Thesis Report, National Institute of Rourkela, Orissa,
2010.
[5]. SonaliSurawdhaniwar, RiteshDiwan. An Improved
Approach of Perturb and Observe Method Over Other
Maximum Power Point Tracking Methods. International
Journal of Recent Technology and Engineering (IJRTE)

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ISSN: 2277-3878, Volume-1, Issue-3, August 2012.pp- 137-
144.
[6]. S.ZahraMirbagheri, SaadMekhilef, S. Mohsen
Mirhassani. MPPT with Inc. Cond method using
conventional interleaved boost converter. Mediterranean
Green Energy Forum 2013 (MGEF-13).Energy Procedia 42
( 2013 ) pp 24 – 32.
[7]. Shridhar Sholapur, R.Mohan, T. R. Narsimhegowda.
Boost Converter Topology for PV System with Perturb And
Observe MPPT Algorithm. IOSR Journal of Electrical and
Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-
1676,p-ISSN: 2320-3331, Volume 9, Issue 4 Ver. II (Jul –
Aug. 2014), pp- 50-56.
[8]. Chetan Sinh Solanki, “Introduction to Photovoltaic
Array”, Eastern Economy Edition, Chapter 4-8, 2014.
BIOGRAPHIES
Shreyash Sharma, IV year, Department of
Electrical Engineering, Chhotubhai
Gopalbhai Patel Institute of Technology,
Bardoli (Gujarat)
Email- shrey4sk@gmail.com
Maharshi Tikiwala, IV year, Department of
Bardoli (Gujarat)
Email-maharshi.tkwala@gmail.com
Ronak Dadhaniya, IV year, Department of
Bardoli (Gujarat)
Email- ronak.cd.ec@gmail.com

Implementation of mppt algorithm on pv panel using pic16 f877 controller

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