1. Implementation of Solar Inverter for On Grid System
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Energy comes in different forms. Light is a form of energy. So is heat. So is
electricity. Often, one form of energy can be turned into another. This fact is very
important because it explains how we get electricity, which we use in so many ways.
Electricity is used to light streets and buildings, to run computers and TVs, and to run
many other machines and appliances at home, at school, and at work. One way to get
electricity is to burn a fuel like oil or coal. This makes heat. The heat then makes
water boil and turn into steam. The steam runs a machine called a turbine that
produces electricity. Often, this electricity then goes into a public power system that
sends it out, through wires, to homes, schools, and businesses over a wide area. This
method for making electricity is popular. But it has some problems. Our planet has
only a limited supply of oil and coal. They are not renewable fuels. Once they are
used, they are gone forever. Also, they give off gases when they are burned. These
gases may make the air dirty, or polluted, and some of them may change the Earth’s
Another way to make electricity uses sunlight. Sunshine is free and never gets
used up also, there is a lot of it. The sunlight that hits the Earth in an hour has more
energy than the people of the world use in a year. A little device called a solar cell can
make electricity right from sunlight (“solar” means having to do with the Sun). A
solar cell doesn’t give off any gases. It doesn’t even make any noise. Solar inverter is
a critical component in a solar energy system. It converts DC power output into AC
current that can be fed into the grid and directly influences the efficiency and
reliability of a solar energy system. On most occasions, 220VAC and 110VAC need
for power supply. Because the direct output of solar energy is usually 12VDC,
24VDC, or 48VDC, it is necessary to use DC-AC inverter in order to be able to
supply power to 220VAC electronic devices.
Inverters are generally rated by the amount of AC power they can supply
continuously. In general, manufacturers provide 5 second and 1/2 hour surge figures
which give an indication of how much power is supplied by the inverter. Solar
inverters require a high efficiency rating. For use of solar cells remains relatively
costly, it is paramount to adopt high efficiency inverter to optimize the performance
of solar energy system.
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High reliability helps keep maintenance cost low. Since most solar power
stations are built in rural areas without any monitoring manpower, it requires that
inverters have competent circuit structure, strict selection of components and
protective functions such as internal short circuit protection, overheating protection
and overcharge protection. Wider tolerance to DC input current plays an important
role since the terminal voltage varies depending on the load and sunlight. Though
energy storage batteries are significant in providing consistent power supply, variation
in voltage increases as the battery’s remaining capacity and internal resistance
condition changes, especially when the battery is ageing, widening its terminal
voltage variation range. In mid-to-large capacity solar energy systems, inverters,
power output should be in the form of sine waves which attain less distortion in
energy transmission. Many solar energy power stations are equipped with gadgets that
require higher quality of the electricity grid, which, when connected to the solar
systems, requires sine waves to avoid electric harmonic pollution from the public
power supply network.
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In the research paper “A New Design of Grid Tie Inverter for a Grid
Interactive Solar Photovoltaic Power Generation” author M. Ghoul state that
Photovoltaic systems that convert Solar energy into Electrical Energy are divided into
two main categories: stand-alone (or) off line and grid connected. The first one is
commonly used in rural areas and more often as a back-up system for situations when
the grid isn’t available due to a natural disaster or human caused disruption. Even if
they are capable of providing AC power for immediate appliance usage, most of the
time these systems make use of energy storage devices such as large capacity
batteries, where the energy stored during the day will then be used when sunlight is
not available. On the other hand, grid-connected systems are installed in areas where
the grid is present and robust, and able to accept energy feeding from the above
described photovoltaic systems. Operating a Renewable System in Parallel with an
Electric Grid requires Special Inverters. This Paper Presents the New Design,
Development & Performance Analysis of a Grid Connected PV Inverter. The
experimental results prove that the proposed system can reduce the Energy
Consumption drastically and give a reliable support to the Grid .
In the research paper of “Implementation of PV Fed Hybrid Multilevel
Inverter using MPPT” by author D. Manoj Nethala state that versatile stand-alone
photovoltaic (PV) systems still demand on at least one battery inverter with improved
characteristics of robustness and efficiency, which can be achieved using multilevel
topologies. A compilation of the most common topologies of multilevel converters is
presented, and it shows which ones are best suitable among the NPC/ Cascaded H-
Bridge to implement inverters for standalone applications in the range of a few
kilowatts. The harmonic content of the output signals of the both the inverters are
In the research paper of “Performance Of The Grid Connected Photovoltaic
System” by author Neeraj and Dwarka Prasad represents the Eco friendly power
generation obtained by sunlight energy through photovoltaic cells. The experimental
model where the energy is fed by traditional means to a 3- phase load has been used.
Efforts have been made to replace the source for load on one of the three phases by a
photovoltaic source. This is going to space the source from feeding 200 KW every
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day. A synchronizer has been developed to enable the parallel operation of
photovoltaic cells with the existing A/C power source. This ensures equal voltages
and equal frequencies of both the sources before putting loads.
In research paper of “Simulation and Design of Low Cost Single Phase
Inverter” presented by Nishita Kapadia and Amit Patel represent that how solar
energy is converted into electrical energy in a cost effective manner. The main
components of this solar system are solar cell, DC to DC boost converters, inverter.
Sine wave push pull inverter topology is used for inverter. In this topology only two
MOSFETs are used and isolation requirement between control circuit and power
circuit is also less which helps to decrease the cost of solar inverter. In this paper
design of components for the booster and inverter are done .
In a research article of the “Simulation and Analysis of a New Grid Connected
Solar Inverter” by author Mohammad Ahmad, B. H. Khan represents that proposes
and analyzes the performance of a new grid connected inverter topology with Solar
PV (SPV) as a dc source. The simulation is done in SIMULINK/ MATLAB Software.
The RMS inverter output voltage is kept slightly higher than the RMS grid voltage
and the power transfer to the grid is controlled by controlling the phase lag angle of
grid with respect to the inverter. It is shown that when the phase lag angle of the grid
is changed, the THD in output current, RMS current, active power and reactive power
changes while RMS voltage and output voltage THD remains approximately the same
In the research paper of “On Grid/Grid Tie Solution” presented by J.H.R.E
slin state that a solar grid tied inverter converts DC outputs of PV modules, AC power
suitable for transmission on the power grid, or use it for your own consumptions
often deploying reactive power to meet new grid codes. It must always optimize the
power output via maximum power point tracking and additionally monitoring both the
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3.1 Types of Solar system
3.1.1 Grid Connected Solar System
A grid-connected photovoltaic power system or grid-connected PV power
system is an electricity generating solar PV power system that is connected to
the utility grid. A grid-connected PV system consists of solar panels, one or
several inverters, a power conditioning unit and grid connection equipment. They
range from small residential and commercial rooftop systems to large utility-
scale solar power stations. Unlike stand-alone power systems, a grid-connected
system rarely includes an integrated battery solution, as they are still very expensive.
When conditions are right, the grid-connected PV system supplies the excess power,
beyond consumption by the connected load, to the utility grid .
Fig 3.1: On Grid System
Residential grid-connected rooftop systems which have a capacity more than
10 kilowatts can meet the load of most consumers. They can feed excess power to the
grid where it is consumed by other users. The feedback is done through a meter to
monitor power transferred. Photovoltaic wattage may be less than average
consumption, in which case the consumer will continue to purchase grid energy, but a
lesser amount than previously. If photovoltaic wattage substantially exceeds average
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consumption, the energy produced by the panels will be much in excess of the
demand. In this case, the excess power can yield revenue by selling it to the grid.
Depending on their agreement with their local grid energy company, the consumer
only needs to pay the cost of electricity consumed less the value of electricity
generated. This will be a negative number if more electricity is generated than
consumed. Additionally, in some cases, cash incentives are paid from the grid
operator to the consumer. Connection of the photovoltaic power system can be done
only through an interconnection agreement between the consumer and the utility
Systems such as Net Metering and Feed-in Tariff which are offered by some
system, operators can offset a customer’s electricity usage costs. In some
locations, though grid technologies cannot cope with distributed generation
feeding into the grid, so the export of surplus electricity is not possible and that
surplus is earthed.
Grid-connected PV systems are comparatively easier to install as they do not
require a battery system.
Grid interconnection of photovoltaic (PV) power generation systems has the
advantage of effective utilization of generating power because there are no storage
A photovoltaic power system is carbon negative over its lifespan, as any energy
produced over and above that to build the panel initially offsets the need for
burning fossil fuels. Even though the sun doesn't always shine, any installation
gives a reasonably predictable average reduction in carbon consumption.
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3.1.4 Stand Alone System :
A free standing or Stand Alone PV System is made up of a number of individual
photovoltaic modules (or panels) usually about 12 volts with power outputs of
between 50 and 100+ watts each. These PV modules are then combined into a single
array to give the desired power output. A simple stand alone PV system is an
automatic solar system that produces electrical power to charge banks of batteries
during the day for use at night when the suns energy is unavailable. A stand alone
small scale PV system employs rechargeable batteries to store the electrical energy
supplied by a PV panel or array. Stand alone PV systems are ideal for remote rural
areas and applications where other power sources are either impractical or are
unavailable to provide power for lighting, appliances and other uses. In these cases, it
is more cost effective to install a single stand alone PV system than pay the costs of
having the local electricity company extend their power lines and cables directly to
A stand alone photovoltaic (PV) system is an electrical system, consisting of an
array of one or more PV modules, conductors, electrical components, and one or more
loads. But a small-scale PV system does not have to be attached to a roof top or
building structures for domestic applications, they can be used for camper vans, RV’s,
boats, tents, camping and any other remote location. Many companies now offer
portable solar kits that allow you to provide your own reliable and free solar
electricity anywhere you go even in hard to reach locations .
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Fig 3.2: Stand Alone System
While a major component and the cost of a standalone PV system is the solar array,
several other components are typically needed. These include:
Batteries: Batteries are an important element in any stand alone PV system,
but can be optional depending upon the design. Batteries are used to store
the solar-produced electricity for night time or emergency use during the
day. Depending upon the solar array configuration, battery banks can be of
12V, 24V or 48V and many hundreds of amperes in total.
Charge Controller: A charge controller regulates and controls the output
from the solar array to prevent the batteries from being over charged (or over
discharged) by dissipating the excess power into a load resistance. Charge
controllers within a standalone PV system are optional but it is a good idea
to have one for safety reasons.
Fuses and Isolation Switches: These allow PV installations to be protected
from accidental shorting of wires allowing power from the PV modules and
system to be turned “OFF” when not required saving energy and improving
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Inverter: The inverter can be another optional unit in a stand alone system.
Inverters are used to convert the 12V, 24V or 48 Volts direct current (DC)
power from the solar array and batteries into an alternating current (AC)
electricity and power of either 120 VAC or 240 VAC for use in the home to
power AC mains appliances such as TV’s, washing machines, freezers, etc.
Wiring: The final component required in and PV solar system is the
electrical wiring. The cables need to be correctly rated for the voltage and
power requirements. The thin telephone wire will not work.
The above two methods, explains about solar inverter project. Out of these
two methods, we use here the solar inverter for on a grid system. Because
this system generates energy and directly use into household or other
application without storing in the battery. Due to this technique the cost
saving is more and there is negligible maintenance required and lots of
advantages as explained in the project.
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4.2 Block Diagramand Circuit Diagram
4.1 Project Bolck Diagram
The above fig shows the block diagram of this project, where we used a
battery for backup purpose. The description of each block and working of this project
is given below.
When light energy strikes the solar cell, electrons are knocked loose from the
atoms in the semiconductor material. If electrical conductors are attached to the
positive and negative sides, forming an electrical circuit, the electrons can be captured
in the form of an electric current that is, electricity. The output of solar panel is
directly given to the bridge which rectifies it and then it is provided to the 7805
regulator. The regulator has gives 5v dc output which is given to the PIC
microcontroller. This PIC is mainly used for generating a pulse, the output of PIC is
taken from pin 15 and 16 then it is given to the transistor, which amplifies the output
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and then it directly fed to the IR2110 MOSFET driver which is used to drive
MOSFET TLP250. The MOSFET performs switching operation during switching
operation there is a voltage drop takes place which gives us 12v DC, which mean
when one MOSFET is ON, other if OFF, so we get an alternate current and then the
output is fed to the center tapped transformer whose center tapped terminal is directly
given to the panel. The other terminal is connected with a MOSFET.
Fig 4.2: Circuit Diagram
The transformer directly convert the 12v DC to 220v AC supply. This supply
is then driven the load. In our project, our main aim is to use grid tie system which
means ON Grid system having a solar panel mounted on roofs of homes. Supposed
we are generating 5 units out of which we just required 3 units so remaining 2 units
will be fed to the utility grid and in the night time as we are not able to use our system
to generate energy in such condition the units which we were fed to utility grid can be
used as a backup. While performing this operation an Electronic energy meter is used
between consumer end and utility grid this meter directly measures the amount of
units, so we can easily define the number of units used by us and fed to the utility
grid. In this way we are ultimately saving cost and energy.
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4.3 Hardware Requirement:
Photo Voltaic Cell
MOSFET Driver IR2110
Center Tapped Transformer
4.4 Photo Voltaic Cell
Photo-voltaic is the direct conversion of light into electricity at the atomic
level. Some materials exhibit a property known as the photoelectric effect that causes
them to absorb photons of light and release electrons. When these free electrons are
captured an electric current results that can be used as electricity .
Fig. 4.3: Photovoltaic Cell
The fig 4.3 illustrates the operation of a basic photovoltaic cell, also called a
solar cell. Solar cells are made of the same kinds of semiconductor materials, such as
silicon, used in the microelectronics industry. For solar cells, thin semiconductor,
positive on one side and negative on the other. When light energy strikes the solar
cell, electrons are knocked loose from the atoms in the semiconductor material. If
electrical conductors are attached to the positive and negative sides, forming an
electrical circuit, the electrons can be captured in the form of an electric current that
is, electricity. This electricity can then be used to supply a load, such as a light or a
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tool. A number of solar cells electrically connected to each other and mounted on a
support structure or frame is called a photovoltaic module. Modules are designed to
supply electricity at a certain voltage, such as a common 12 volt system. The current
produced is directly dependent on how much light strikes the module.
Fig 4.4: Solar Cell Structure
Multiple modules can be wired together to form an array. In general the larger
the area of a module or array, the more electricity that will be produced. Photovoltaic
modules and arrays produce direct-current (dc) electricity. They can be connected in
both series and parallel electrical arrangements to produce any required voltage and
Today's most common PV devices use a single junction, or interface, to create
an electric field within a semiconductor such as a PV cell. In a single-junction PV
cell, only photons whose energy is equal to or greater than the band gap of the cell
material can free an electron for an electric circuit. In other words, the photovoltaic
response of single junction cells is limited to the portion of the sun's spectrum whose
energy is above the band gap of the absorbing material, and lower-energy photons are
not used. One way to get around this limitation is to use two (or more) different cells,
with more than one band gap, and more than one junction, to generate a voltage.
These are referred to as "multifunction" cells (also called "cascade" or "tandem"
cells). Multi junction devices can achieve higher total conversion efficiency because
they can convert more of the energy spectrum of light to electricity .
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As shown in fig 4.4, a multifunction device is a stack of individual single-
junction cells in descending order of the band gap. The top cell captures the high-
energy photons and passes the rest of the photons on to be absorbed by the lower-
band-gap cells. The Solar cell is the basic unit of solar energy generation system
where electrical energy is extracted directly from light energy without any
intermediate process. The working of a solar cell solely depends upon its photovoltaic
effect, hence a solar cell also known as photovoltaic cells. A solar cell is basically a
semiconductor device. The solar cell produces electricity while light strikes on it and
the voltage or potential difference, established across the terminals of the cell is fixed
to 0.5 volt and it is nearly independent of intensity of incident light whereas the
current capacity of the cell is nearly proportional to the intensity of incident light as
well as the area that exposed to the light. Each of the solar cells has one positive and
one negative terminal like all other types of battery cells. Typically a solar or
photovoltaic cell has negative front contact and positive back contact a semiconductor
PN junction is in the middle of these two contacts surface. The rate of production of
current in a solar cell also depends upon the intensity of light and the angle at which
the light falls on the cell.
As the current production also depends upon the surface area of the cell
exposed to light, it is better to express maximum current density instead maximum
current. Maximum current density or short circuit current density rating is nothing but
the ratio of maximum or short circuit current to the exposed surface area of the cell.
Where, Isc is short circuit current, Jsc maximum current density and A is the area of
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4.4.1 Efficiency of Solar Cell
It is defined as the ratio of maximum electrical power output to the radiated
power input to the cell and it is expressed in percentage. It is considered that the
radiated power of the earth is about 1000 watts/square meter, hence if the exposed
surface area of the cell is a total radiated power on the cell it will be 1000 watts.
Conventional solar cells are made of Silicon (Si) single crystal and have an efficiency
of around 22-24%, while polycrystalline Silicon (Si) cells have an efficiency of 18%.
The efficiency of the solar cell depends on the band gap of the material.
Efficiency of solar panel = (Maximum electrical power output/ Radiation
Power input to the cell)
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4.5 MOSFET Driver IR2110
In many applications, floating circuit is required to drive the high side
MOSFET. In H bridge used in pure sine wave inverter design 2 MOSFET are used as
high side MOSFET and 2 MOSFET are used as low side MOSFET. International
rectifiers IR2110 MOSFET driver can be used as high side and a low side MOSFET
driver. It has a floating circuit to handle to bootstrap operation. IR2210 can withstand
voltage up to 500v (offset voltage). Its output pins can provide peak current up to 2
ampere. It can also be used to as IGBT driver. The IR2210 floating circuit can drive
high side MOSFET up to 500 volt .
Fig 4.5: Typical connection of IR2110
Pin 1 is the output of the low side MOSFET drive
Pin2 is a return path for low side. It is at same potential as ground VSS pin
13. Because when input to low side at pin 12 Lin is high, LO output will be
equal to the value of the Vcc voltage at pin 3 with respect to Vss and COM
pin. When the input to lower side at pin 12 Lin is low, LO output will be
equal to the value of VSS and its means zero.
VDD pin 9 is a logic supply pin. Its value should be should be between 5
volts. But if you used voltage less than 4 volts it many not give you required
HIN Pin 10 is an input signal for high side MOSFET driver output. It may be
from a microcontroller or any other device. But the input signal logic level
should be between 4-5 volt.
LIN pin 12 is the input signal for low side MOSFET driver output. It may be
from a microcontroller or any other device. But the input signal logic level
should also be between 4-5 volt.
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SD pin 11 is used a shutdown pin. You can use it for protection circuit. For
example, in over voltage or over current protection circuit, if any of these
values become greater than the specified value, you can give 5 volt signal to
shut down IR2210 driver to stop driving MOSFETS. In return, your circuit
will stop working.
VB pin 6 is used as a high side floating supply or floating circuit to provide
floating voltage to a high side MOSFET
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4.6 Centre Tapped Transformer
A Transformer is an electrical static machine that takes electricity of one
voltage and changes it into another voltage. In AC circuits, AC voltage, current and
waveform can be transformed with the help of Transformers. Transformer plays an
important role in electronic equipment. AC and DC voltage in Power supply
equipment are almost achieved by transformer’s transformation and rectification. A
Transformer takes in electricity at a higher voltage and lets it run through lots of coils
wound around an iron core. “. A single-phase Transformer can operate to either
increase or decrease the voltage applied to the primary winding. Because the current
is alternating, the magnetism in the core is also alternating. Also around the core is an
output wire with fewer coils. The magnetism changing back and forth makes a current
in the wire. Having fewer coils means less voltage. When it is used to “decrease” the
voltage on the secondary winding with respect to the primary it is called a Step-down
Transformer. When a Transformer is used to “increase” the voltage on its secondary
winding with respect to the primary, it is called a Step-up Transformer.
When an additional wire is connected across exact the middle point of the
secondary winding of the transformer then it is called as Centre tapped transformer.
The wire is adjusted such that it falls exact in the middle point of the secondary
winding and thus at zero volts, forming the neutral point of the winding. This is called
centre tapped and this thing allows the transformer to provide the two separate output
voltage which are equal in magnitude, but opposite in polarity to each other.
Fig 4.6: Centre tapped transformer
It can be seen from fig that this type of configuration gives us two passes
through the two parts of the secondary coil, and a total of three wires, in which the
middle one the center tapped wire is neutral one. So this center tapped configuration
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is also known as two phase three wire transformer systems. In this way half the
voltage appears across the half of the phase, that is from line 1 to neutral and the other
half of the voltage appears across the next phase, that is from neutral to line 2. If the
load is connected directly between line 1 and line 2, then we get a total voltage that is
the sum of the two voltages. This way we can get more ampere of current at the same
The working principle of Transformer is very simple. It depends
upon Faraday’s law of electromagnetic induction. Actually, mutual induction between
two or more winding is responsible for transformation action in an Electrical
Transformer. According to Faraday’s law of electromagnetic induction “Rate of
change of flux linkage with respect to time is directly proportional to the induced
EMF in a conductor or coil“. When one winding which is supplied by an alternating
electrical source as shown in figure 4.7. The alternating current through the winding
produces a continually changing flux or alternating flux that surrounds the winding. If
any other winding is brought nearer to the previous one, obviously some portion of
this flux will link with the second. As this flux is continually changing in its
amplitude and direction, there must be a change in flux linkage in the second winding
or coil. According to Faraday’s law, there must be an EMF induced in the second. If
the circuit of the latter winding is closed, there must be an electric current flowing
Fig 4.7: Working of center tapped transformer
The winding which takes electrical power from the source, is generally known
as Primary winding of Transformer as shown in figure 4.7. The winding which gives
the desired output voltage due to mutual induction in the transformer, is commonly
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known as Secondary winding of a Transformer. The difference in voltage between the
Primary and the Secondary windings is achieved by changing the number of coil turns
in the Primary winding compared to the number of coil turns on the Secondary
winding. As the Transformer is a linear device, a ratio is done between the number of
turns of the primary coil divided by the number of turns of the secondary coil. This
ratio, called the ratio of transformation, more commonly known as a Transformers
“turns ratio”. This turn’s ratio value dictates the operation of the Transformer and the
corresponding voltage available on the secondary winding. If the Transformer’s ratio
is 10:1, then if there are 2200 volts on the Primary winding there will be 220 volts on
the Secondary winding. Then we can see that if the ratio between the numbers of turns
changes the resulting voltages must also change by the same ratio.
In this project the rating of the transformer is 12/230v and current is 0.86A.
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The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistor
is a semiconductor device which is widely used for switching and amplifying
electronic signals in the electronic devices. The MOSFET is a core of integrated
circuit and it can be designed and fabricated on a single chip because of these very
small sizes. The MOSFET is a four terminal device with source(S), gate (G), drain
(D) and body (B) terminals. The body of the MOSFET is frequently connected to the
source terminal so making it a three terminal device like a field effect transistor. The
MOSFET is very far the most common transistor and can be used in both analog and
digital circuits. The MOSFET works by electronically varying the width of a channel
along which charge carriers flow (electrons or holes). The charge carriers enter the
channel at the source and exit via the drain. The width of the channel is controlled by
the voltage on an electrode is called gate which is located between the source and
drain. It is insulated from the channel near an extremely thin layer of metal oxide. The
MOS capacity present in the device is the main part .
Fig 4.8: Construction of MOSFET
The aim of the MOSTFET is to be able to control the voltage and current flow
between the source and drain. It works almost as a switch. The working of MOSFET
depends upon the MOS capacitor. The MOS capacitor is the main part of the
MOSFET. The semiconductor surface at the below oxide layer which is located
between the source and drain terminals. It can be inverted from p-type to n-type by
applying positive or negative gate voltages respectively. When we apply the positive
gate voltage the holes present under the oxide layer with a repulsive force and holes
are pushed downward with the substrate. The deflection region populated by the
bound negative charges which are associated with the acceptor atoms. The electrons
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reach channel is formed. The positive voltage also attracts electrons from the n+
source and drain regions into the channel. Now, if a voltage is applied between the
drain and source, the current flows freely between the source and drain and the gate
voltage controls the electrons in the channel. Instead of positive voltage if we apply
negative voltage, a whole channel will be formed under the oxide layer .
Fig 4.9: Working of MOSFET
4.7.2 N- Channel MOSFET:
The N-Channel MOSFET has a N- channel region between source and drain It
is a four terminal device such as gate, drain, source, body. This type of MOSFET the
drain and source is heavily doped n+ region and the substrate or body is P- type. The
current flows due to the negatively charged electrons. When we apply the positive
gate voltage the holes present under the oxide layer pushed downward into the
substrate with a repulsive force. The deflection region is populated by the bound
negative charges which are associated with the acceptor atoms. The electrons reach
channel is formed. The positive voltage also attracts electrons from the n+ source and
drain regions into the channel. Now, if a voltage is applied between the drain and
sources the current flows freely between the source and drain and the gate voltage
controls the electrons in the channel. Instead of positive voltage if we apply negative
voltage a whole channel will be formed under the oxide layer .
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Table 4.2: Rating of MOSFET
TYPE VDSS RDS ID
STP55NF06L 60V < 0.018 55
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The PIC16F877A is one of the most renowned microcontroller in the industry.
This controller is very convenient to use, the coding or programming of this controller
is also easier. One of the main advantages is that it can be write-erase as many times
as possible because it uses FLASH memory technology. It has a total number of 40
pins and there are 33 pins for input and output. PIC16F877A is used in many PIC
microcontroller projects. PIC16F877A also have much application in digital
electronics circuits .
Fig 4.10: Pin diagram of PIC16F877A
The first pin is the master clear pin of this IC. It resets the microcontroller and
is active low, meaning that it should constantly be given a voltage of 5V and if 0 V
are given then the controller is reset. Resetting the controller will bring it back to the
first line of the program that has been burned into the IC.
2. PIN 2: RA0/AN0
PORT A consists of 6 pins, from pin 2 to pin 7, all of these are bidirectional
input/output pins. Pin 2 is the first pin of this port. This pin can also be used as an
analog pin AN0. It is built in analog to digital converter.
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3. PIN 3: RA1/AN1
This can be the analog input 1.
4. PIN 4: RA2/AN2/Vref-
It can also act as the analog input2. Or negative analog reference voltage can
be given to it.
5. PIN 5: RA3/AN3/Vref+
It can act as the analog input 3. Or can act as the analog positive reference
6. PIN 6: RA0/T0CKI
To timer0 this pin can act as the clock input pin, the type of output is open
7. PIN 7: RA5/SS/AN4
This can be the analog input 4. There is synchronous serial port in the
controller also and this pin can be used as the slave select for that port.
8. PIN 8: RE0/RD/AN5
PORT E starts from pin 8 to pin 10 and this is also a bidirectional input output
port. It can be the analog input 5 or for parallel slave port it can act as a ‘read control’
pin which will be active low.
9. PIN 9: RE1/WR/AN6
It can be the analog input 6. And for the parallel slave port it can act as the
‘write control’ which will be active low.
10. PIN 10: RE2/CS/A7
It can be the analog input 7, or for the parallel slave port it can act as the
‘control select’ which will also be active low just like read and write control pins.
11. PIN 11 and 32: VDD
These two pins are the positive supply for the input/output and logic pins.
Both of them should be connected to 5V.
12. PIN 12 and 31: VSS
These pins are the ground reference for input/output and logic pins. They
should be connected to 0 potential.
13. PIN 13: OSC1/CLKIN
This is the oscillator input or the external clock input pin.
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14. PIN 14: OSC2/CLKOUT
This is the oscillator output pin. A crystal resonator is connected
between pin 13 and 14 to provide an external clock to the microcontroller. ¼
of the frequency of OSC1 is outputted by OSC2 in case of RC mode. This
indicates the instruction cycle rate.
Fig 4.11: Crystal Osicalltor
15. PIN 15: RC0/T1OCO/T1CKI
PORT C consists of 8 pins. It is also a bidirectional input, output port. Of
them, pin 15 is the first. It can be the clock input of timer 1 or the oscillator output of
16. PIN 16: RC1/T1OSI/CCP2
It can be the oscillator input of timer 1 or the capture 2 inputs/compare 2
output/ PWM 2 output.
17. PIN 17: RC2/CCP1
It can be the capture 1 input/ compare 1 output/ PWM 1 output.
18. PIN 18: RC3/SCK/SCL
It can be the output for SPI or I2C modes and can be the input/output for
synchronous serial clock.
19. PIN 23: RC4/SDI/SDA
It can be the SPI data in pin. Or in I2C mode it can be data input/output pin.
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20. PIN 24: RC5/SDO
It can be the data out of SPI in the SPI mode.
21. PIN 25: RC6/TX/CK
It can be the synchronous clock or USART Asynchronous transmit pin.
22. PIN 26: RC7/RX/DT
It can be the synchronous data pin or the USART receive pin.
23. PIN 19,20,21,22,27,28,29,30:
All of these pins belong to PORTD which is again a bidirectional input and
output port. When the microprocessor bus is to be interfaced, it can act as the parallel
24. PIN 33-40: PORT B
All these pins belong to PORTB. Out of which RB0 can be used as the
external interrupt pin and RB6 and RB7 can be used as in-circuit debugger pins.
The available features are summarized in Table 4.2. Block diagrams of the
PIC16F873A/876A and PIC16F874A/877A devices are provided in the table, respectively.
The pin outs for these device families are listed above.
Table 4.3: PIC16F877A device features
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High-Performance RISC CPU:
•Only 35 single-word instructions to learn
•All single-cycle instructions except for program branches, which are two-cycle
•Operating speed: DC – 20 MHz clock input DC – 200 ns instruction cycle
•Up to 8K x 14 words of Flash Program Memory,
Up to 368 x 8 bytes of Data Memory (RAM),
Up to 256 x 8 bytes of EEPROM Data Memory
•Pin-out compatible to other 28-pin or 40/44-pin
•Timer0: 8-bit timer/counter with 8-bit pre-scalar
•Timer1: 16-bit timer/counter with pre-scalar, can be incremented during Sleep via
•Timer2: 8-bit timer/counter with 8-bit period register, pre-scalar and post-scalar
•Two Capture, Compare, PWM modules
-Capture is 16-bit, the max resolution is 12.5 ns
-Compare is 16-bit, the max resolution is 200 ns
-PWM max resolution is 10-bit
•10-bit, up to 8-channel Analog-to-Digital Converter (A/D)
•Brownout Reset (BOR)
•Analog Comparator module with:
-Two analog comparators
-Programmable on-chip voltage reference (VREF) module
-Programmable input multiplexing from device inputs and internal voltage reference.
•Low-power, high-speed Flash/EEPROM technology
•Fully static design
•Wide operating voltage range (2.0V to 5.5V)
•Commercial and Industrial temperature ranges
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4.9 LM 7805 Regulator
The LM7805 series of three terminal regulators are available with several
fixed output voltages making them useful in a wide range of applications. One of
these is local on card regulation, eliminating the distribution problems associated with
single point regulation. The LM7805 series is available in an aluminum TO-3 package
which will allow over 1.0A load current if adequate heat sinking is provided. Current
limiting is included to limit the peak output current to a safe value. Safe area
protection for the output transistor is provided to limit internal power dissipation. If
internal power dissipation becomes too high for the heat sinking provided, the thermal
shutdown circuit takes over preventing the IC from overheating. Considerable effort
was expanded to make the LM7805 series of regulators easy to use and minimize the
number of external components. It is not necessary to bypass the output, although this
does improve transient response. Input bypassing is needed only if the regulator is
located far from the filter capacitor of the power supply. For output voltage other than
5V, 12V and 15V the LM117 series provides an output voltage range from 1.2V to
Output current in excess of 1A Internal thermal overload protection
No external components required
Output transistor safe area protection
Internal short circuit current limit
Available in the aluminum TO-3 package
Fig 4.12: LM7805 Regulator
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4.10 PWM Technique
Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is a
modulation technique used to encode a message into a pulsing signal. Although this
modulation technique can be used to encode information for transmission, its main
use is to allow the control of the power supplied to electrical devices, especially to
inertial loads such as motors. In addition, PWM is one of the two principal algorithms
used in photovoltaic solar battery chargers, the other being maximum power point
tracking. The average value of the voltage (and current) fed to the load is controlled
by turning the switch between supply and load on and off at a fast rate .
The PWM switching frequency has to be much higher than what would affect
the load (the device that uses the power), which is to say that the resultant waveform
perceived by the load must be as smooth as possible. The rate (or frequency) at which
the power supply must switch can vary greatly depending on load and application, for
example Switching has to be done several times a minute in an electric stove; 120 Hz
in a lamp dimmer; between a few kilohertz (kHz), to tens of kHz for a motor drive;
and well into the tens or hundreds of kHz in audio amplifiers and computer power
Fig 4.13: Output of PWM
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The term duty cycle describes the proportion of 'on' time to the regular interval
or 'period' of time; a low duty cycle corresponds to low power, because the power is
off for most of the time. Duty cycle is expressed in percent, 100% being fully on. The
main advantage of PWM is that power loss in the switching devices is very low.
When a switch is off there is practically no current, and when it is on and power is
being transferred to the load, there is almost no voltage drop across the switch. Power
loss, being the product of voltage and current, is thus in both cases close to zero .
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4.11.1 Electrical Load Detail:
1 No’s of 100W Computer use for 8 Hours/Day
2 No’s of 60W Fan use for 8 Hours/Day
1 No’s of 100W CFL Light use for 8 Hours/Day
4.11.2 Solar System Detail:
Solar System Voltage (As per Battery Bank) = 48V DC
Loose Wiring Connection Factor = 20%
Daily Sunshine Hour in Summer = 6 Hours/Day
Daily Sunshine Hour in Winter = 4.5 Hours/Day
Daily Sunshine Hour in Monsoon = 4 Hours/Day
4.11.3 Inverter Detail:
Future Load Expansion Factor = 10%
Inverter Efficiency = 80%
Inverter Power Factor =0.8
Step-1: Calculate Electrical Usages per Day
Power Consumption for Computer = No x Watt x Use Hours/Day
Power Consumption for Computer = 1x100x8 =800 Watt Hr/Day
Power Consumption for Fan = No x Watt x Use Hours/Day
Power Consumption for Fan = 2x60x8 = 960 Watt Hr/Day
Power Consumption for CFL Light = No x Watt x Use Hours/Day
Power Consumption for CFL Light = 1x100x8 = 800 Watt Hr/Day
Total Electrical Load = 800+960+800 =2560 Watt Hr/Day
Step-2: Calculate Solar Panel Size
Average Sunshine Hours = Daily Sunshine Hour in Summer+ Winter+ Monsoon
Average Sunshine Hours = 6+4.5+4 / 3 =8 Hours
Total Electrical Load =2560 Watt Hr/Day
Required Size of Solar Panel = (Electrical Load / Avg. Sunshine) X Correction
Required Size of Solar Panel =(2560 / 4.8) x 1.2 = 635.6 Watt
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Required Size of Solar Panel = 635.6 Watt
Step-3: Calculate No of Solar Panel / Array of Solar Panel
If we Use 250 Watt, 24V Solar Panel in Series-Parallel Type Connection
In Series-Parallel Connection Both Capacity (watt) and Volt are increases
No of String of Solar Panel (Watt) = Size of Solar Panel / Capacity of Each Panel
No of String of Solar Panel ( Watt) = 635.6 / 250 = 2.5 No’s Say 3 No’s
No of Solar Panel in Each String= Solar System Volt / Each Solar Panel Volt
No of Solar Panel in Each String= 48/24 =2 No’s
Total No of Solar Panel = No of String of Solar Panel x No of Solar Panel in Each
Total No of Solar Panel = 3×2 =6 No’s
Total No of Solar Panel =6 No’s
Step-4: Calculate Electrical Load:
Load for Computer = No x Watt
Load for Computer = 1×100 =100 Watt
Load for Fan = No x Watt
Load for Fan = 2×60 = 120 Watt
Load for CFL Light = No x Watt
Load for CFL Light = 1×100 = 100 Watt
Total Electrical Load = 100+120+100 =320 Watt
Step-5: Calculate Size of Inverter:
Total Electrical Load in Watt = 320 Watt
Total Electrical Load in VA= Watt /P.F
Total Electrical Load in VA =320/0.8 = 400VA
Size of Inverter =Total Load x Correction Factor / Efficiency
Size of Inverter = 320 x 1.2 / 80% =440 Watt
Size of Inverter =400 x 1.2 / 80% =600 VA
Size of Inverter = 440 Watt or 600 VA
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Required Size of Solar Panel = 635.6 Watt
Size of Each Solar Panel = 250 Watt. 12 V
No of String of Solar Panel = 3 No’s
No of Solar Panel in Each String = 2 No’s
Total No of Solar Panel =6 No’s
Total Size of Solar Panel = 750 Watt
Size of Inverter = 440 watt or 600 VA
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4.12 PCB Design
Printed circuit board is a piece of art. The performance of an electronic circuit
depends upon the layout and design of the PCB. The PCB design of the circuit
operation should be very precise to work it properly. The soldered point should be
small enough so that any stray between these points should not exist. Also high
package density of components can produce stray which should be avoided by proper
circuit designing and components should be spread in such a way that two-component
produce minimum stay. Also the track of the PCB, soldering points and components
mounting should be very correct and that will be of great help to success the project.
Making such precise PCB is easy. For preparing the PCB layout, we used the
PCB layout, manufacturing by the Vega company with a help of computerized
equipment. We can not use ready made PCB for our project. To make the PCB with a
professional touch, the general method that should be carried out is as follows.
4.12.1 Layout Planning:
The layout of the PCB has to incorporate all information on the board, before
one can proceed further for the artwork preparation. This planning procedure depends
on many factors.
4.12.2 Layout Scale:
Depending upon the accuracy required artwork produced should be at 1:1 or
2:1 scale. Accordingly the size of the artwork will be equal to four times or sixteen
times of that actual PCB. The layout is best prepared on the same scale as artwork.
4.12.3 Layout Sketch:
The end product of the layout design is the pencil sketched component and
conductor driving, which is called layout sketch. It contains all relevant information
for preparation of artwork.
Besides the components outlines, components holes and interconnection line
(patterns) the layout should also include the information on.
Diameter of component hole, IC transistor pads.
The minimum spacing between the conductive lines that must produce.
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4.13 Project Setup
Fig 4.14: Project Setup
Fig 4.15: Solar Panel
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ADVANTAGES & DISADVANYAGES
Direct conversion of light to electricity:- It requires a simple solar panel
which converts light energy directly into electricity.
Absence of moving parts:- There is no any moving part required for this
system as all the equipments used are static. So it reduced the maintenance.
Maintenance cost:- It required low maintenance cost as they are operating on
solar radiations and required no moving parts
Pollution free:- As the system operates on solar radiations only, it does not
It is highly reliable:- Due to the absence of moving parts it is highly reliable
and life span of such system is near about 20-25 years.
A grid connected photovoltaic power system will reduce the power bill as it is
possible to sell surplus electricity produced to the local electricity supplier.
Grid connected PV system is comparatively easy to install as they do not
require a battery system.
Grid interconnection of photovoltaic (PV) power generation system has the
advantages of effective utilization of generating power because there are no
storage losses involved.
A photovoltaic power system is carbon negative over its lifespan, as any
energy produced over and above that to build the panel initially offsets the
need for burning fossil fuels. Even though the sun doesn’t always shine, any
installation gives a reasonably predictable average reduction in carbon
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Whole system depends upon solar radiation: - The major disadvantages of
this project is that lack of solar radiation available. When there is sufficient
amount of solar radiation available, then only this system works otherwise we
have to use battery as a backup.
The initial cost is high: - This system required high initial cost as per our
household requirement. Once this system is installed it serves as a long time
near about 25-30 years.
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In this project the generated energy is primarily used for household purposes
by converting it into AC. If the energy generation is more than our requirement, then
it will be provided to the utility grid, but this happens only if the generating voltage
exceeds 10% of supply voltage. These unit use as a backup supply for the system
when there is no generation of solar energy.
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From this project we observed that this solar inverter is producing electricity
free of cost by using solar energy, so its eco- friendly and pollution free and can be
used for domestic appliances as well as for industrial purpose on three phases. PV is a
technology that does not build from the old technology base, but rather replaces that
base from the bottom up. PV allows people the opportunity to ignore traditional
electric power supply structures and meet their own power needs locally. In rural
regions of the world today where there are no power companies offering electricity
PV is often the technology of the choice.
The unique aspect of an on grid system that we are using in this project is that,
if your system is generating more power than you are using, the excess will flow back
into the grid, turning your meter backwards. In this way the extra amount of power
which are given to the utility grid, we can use it whenever required. In our project we
can use only the energy which is required to drive electrical appliances remaining
energy we are giving it to utility grid means we are saving money.
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The future is bright for continued PV technology dissemination in the world.
PV technology fills a significant need in supplying electricity, creating local jobs and
promoting economic development in rural areas, while also having the positive
benefits of avoiding the external environmental costs associated with traditional
electricity generating technologies. People who choose to pursue a renewable and
sustainable energy future now are the ones showing the way for the future. There is
also saving in cost in use of utility supply. For the record, of the energy which is
going to utility side, we use net meter. Also, we can use MPPT for maximizing the
power under any extracting condition.
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