Photoelectric effect , agricultural engineering, agriculture, bsc agriculture, soil and water conservation engineering,

1. SOLAR PHOTOVOLTAIC SYSTEM
• Solar photovoltaic conversion is the direct conversion of sunlight into
electricity without going through any thermal process. Energy conversion
device for photovoltaic conversion is called a photovoltaic cell or solar cell.
• The word ‘photovoltaic’ consists of the two words, photo and Volta. Photo
stands for light (Greek phõs, photós: light) and Volta (Count Volta, 1745–
1827, Italian physicist) is the unit of the electrical voltage. In other words,
photovoltaic means the direct conversion of sunlight to electricity. The
common abbreviation for photovoltaic is PV.
• Photovoltaic devices are in solid state; therefore they are strong, simple in
design and require very little maintenance. The biggest advantage of solar
photovoltaic device is that they can be constructed as stand-alone system
to give outputs from micro watts to mega watts. That is why, they have
been used as the power source for calculators, watches, water pumping,
remote buildings, communications, satellites, space vehicles and even
mega watt scale power plants.

2. History of Solar Photovoltaic System
• The photovoltaic effect was first observed in electrolytic cells by a French
scientist Becquerel in 1839 who found that more current can be generated
if more light is allowed to fall in the cell. He also discovered that the
increase in current is dependant on the wavelength of light.
• Adam and Day first observed the same effect in solids in 1877 while
working with selenium.
• In 1877, Heinrich Hertz discovered that ultra violet light altered the lowest
voltage capable of causing a spark to jump between two metal electrodes.
• In 1905, the photovoltaic principle was explained by Albert Einstein. He
explained that light behaves like a particle rather than a wave. The energy
of each light particle, called photon, depends on its frequency only and is
equal to the product of Planck’s constant (h) and frequency of light (f).
• An electron in an atom of some materials is able to capture a photon and
obtains energy necessary to escape if energy of photon exceeds the
binding energy of electron in the atom. Under certain situations, these
freed electrons can be made to flow in an external circuit and hence
produce electricity.
• In 1954, researchers at RCA and Bell Laboratories, USA reported achieving
efficiencies of about 6 percent by using devices made of p and n type
semiconductors.
• Photovoltaic cell most commonly made of silicon, a material called
semiconductor, has now been widely used for generating DC electricity.

3. Some Information about Solar Cell
• Current generation in a solar cell is normally 300 Amperes per square
meter area of cell or 30 mA per square centi meter area of cell in a full
sunny day
• Voltage generation per solar cell is normally from 0.4 – 0.5 Volt
• A silicon solar cell of size 10 cm x 10 cm produces a voltage of 0.5 V and
power output of 1 watt at a solar radiation intensity of 1000 watt/m2
• Total cost of the photovoltaic system is around Rs. 100 per solar watt
• A house normally needs 1000 watts (1 kW)
• Cost of installation of the system is Rs. 1.00 lakhs
• Life time of a solar system is around 25 years.
• The size of a solar cell is normally 10 cm x 10 cm
• A commercial solar module contains nearly 36 cells. Each module may
have 3 to 5 columns of cells in series in such a way that it supplies the
desired output to charge a 12 V battery.
• The term ‘Peak Watt’ or Watt Peak’ (wp) is used for power produced by a
photovoltaic device around noon on a clear day with beam radiation
falling normally on the device and operating at a cell temperature of 25-28
degree Centigrade with solar radiation of 1000 watt/m2. It is the higher
output than that usually achieved in the field condition.
• The present annual world power production from photovoltaic system is
about 10 Mwp while in India about 2 Mwp.

4. Applications of Solar Photovoltaic Systems
1. Solar street lighting system
2. Home lighting systems
3. Water pumping systems (for micro irrigation
and drinking water supply)
4. Space vehicles and satellites
5. Community radio and television sets
6. Battery charging
7. Weather monitoring
8. Power source for navigational lights
9. Power source for telecommunication
equipments
10. Power source for railway signaling
equipments.

5. The advantages of solar photovoltaic system
1. Absence of moving parts.
2. Direct conversion of light to electricity at room
temperature.
3. Can function unattended for long time.
4. Low maintenance cost.
5. No environmental pollution.
6. Very long life.
7. Highly reliable.
8. Solar energy is free and no fuel required.
9. Can be started easily as no starting time is involved.
10. Easy to fabricate.
11. These have high power-to-weight ratio, therefore very
useful for space application.
12. Decentralized or dispersed power generation at the
point of power consumption can save power
transmission and distribution costs.
13. These can be used with or without sun tracking.

6. Limitations of solar photovoltaic system
• Manufacture of silicon crystals is labour
and energy intensive.
• Low efficiency.
• The insolation is unreliable and therefore
storage batteries are needed.
• Solar power plants require very large
land areas.
• Electrical generation cost is very high.
• The energy spent in the manufacture of
solar cells is very high.
• High initial cost

7. Insulator, Semi conductor and
Conductor
• On the basis of band energy (the difference in energy of
an electron in the valence band and conduction band),
the materials can be classified as insulator, semi-
conductor and conductor.
• In the energy band model, electrons fill the bands one
after another starting with the first, lowest energy band.
• The highest fully occupied band is called the valence
band (VB). The next highest band, which can be
partially occupied or totally empty, is called the
conduction band (CB).
• The space between the valence band and conduction
band contains forbidden energy states and is therefore
called the forbidden band (FB). The energy gap between
the bands is called the band gap Eg.
CONTD.

9. • Electrons in the outermost band of an atom
determine how an atom will react or join with a
neighboring atom, the outermost band is called the
valence band. Some electrons in the valence band
may be so energetic that they may jump into a still
higher band and are so far removed from the
nucleus that a small amount of impressed force
would cause them to move away from the atom.
Such electrons are responsible for the conduction of
electricity and this remote band is called a
conduction band.
• Materials whose valence bands are full have very
high band gap (more than 3 eV). Such materials are
insulators. Materials on the other hand that have
relatively empty valence band and may have some
electrons in the conduction band are good
conductors. Metals fall in this category. Materials
with valence band partly filled have intermediate
band gaps (less than 3 eV). Such materials are called
semi conductor.

11. Why some semiconductors are photo sensitive
(The photo effect)
• Light, with its photon energy, can provide the energy to lift an electron to a
higher orbit.
• The photon energy is given by:E = hc/λ where h = Planck’s constant (6.63 x
10-34 joule-second); c = speed of light (3 x 108 m/sec). Putting the values and
1 eV = 1.60 x 10-19 Joule; λ = 1.24/Energy of photon; where λ is in microns
(10-6 meter) and energy of photon is in eV (electron volt).
• If energy of photon is equal to the binding energy or forbidden energy gap
(Eg) between valence band and conduction band, the electron after
absorption of photon becomes excited and jumps to the conduction band
and becomes free electrons for assisting in generating electricity.
• λc = 1.24/ Eg; where λc is the critical or cut-off wavelength of light whose
energy becomes equal to band energy.If λ> λc ; then the energy of photon is
less than Eg for which the electron in the valence band does not get
sufficient energy to jump into the conduction band. Hence the above
relationship is very important to differentiate the material to be photo
sensitive to sunlight based on their forbidden energy gap.

12. Why silicon and germanium are photo sensitive to
sunlight
• The band gap (Eg) for silicon and germanium is 1.1 eV
and 0.72 eV respectively. Putting the values in the
relationship λc = 1.24/ Eg; λ= 1.12 microns for silicon
(which is within the spectral region of sunlight)
• λ= 1.72 microns for germanium (which is also within the
spectral region of sunlight)
• λ= 0.2 microns for carbon having band gap of 6 eV (which
is not within the spectral region of sunlight)
• For a conductor band gap energy is very very less and
Eg≈0. In this case λ > 10 microns which is in the infrared
radiation range but not available in the sunlight.
• From the analysis, it is clear that only semiconductors
like silicon and germanium are sensitive to sunlight but
not metal (conductor) or insulator. Some candidate
materials for photovoltaic cell in the band gap range of 1
to 2 eV are SiC (band gap of 2.00 eV), CdSe (band gap of
1.74 eV), GaAs (band gap of 1.40 eV) etc.

13. Some elements in 3rd, 4th and 5th groups of
Periodic Table
III rd IVth Vth
Boron Carbon (insulator) Nitrogen
Aluminum Silicon(Semiconductor) Phosphorus
Galium Germanium(Semiconductor) Arsenic
Group
Elements
Indium Tin (Metal) Antimony
•Silicon and Germanium are tetravalent i.e., there are four valence electrons
in their outermost shell. At about 0 K, both behave as insulator, no free
electrons available in the conduction band. At about 300 K (room
temperature), some electrons may acquire sufficient thermal energy to break
the covalent bond and jump valence band to the conduction band. Some
free electrons available in the conduction band for conduction at room
temperature.
Electronic configuration of
Silicon atom

14. Intrinsic and Extrinsic
semiconductor
• A pure semiconductor is called intrinsic
semiconductor. Here no free electrons are available
since all the covalent bonds are complete and
conduction band is empty or unfilled. A pure
semiconductor therefore behaves as an insulator.
• The semiconductor when added or doped with
impurities is called extrinsic semiconductor. The
process of adding impurity (extremely in small
amounts about 1 part in 108) to a semiconductor to
make it extrinsic semiconductor is called Doping. The
doped semiconductor attains current conducting
properties. If to an intrinsic semiconductor, there is
added a small percentage of trivalent or pentavalent
atoms, a doped, impure or extrinsic semiconductor is
formed.

15. Donor atom and N-type semiconductor
• If the dopants (like Phosphorus, Arsenic or Antimony) having five
valence electrons are added to Si or Ge, they donate one extra
electron (negative charge) per atom and therefore referred to as
donor atom and semiconductor will become N-type semiconductor.

16. Acceptor atom and P-type semiconductor
• If the dopants (like Boron, Gallium or Indium) having three valence
electrons are added to Si or Ge, only three of the covalent bond can be
filled and vacancy that exists in the fourth bond constituting a hole. Such
impurities create holes (vacancy of electron or positive charge) which
can accept valence electron from the semiconductor and are called
acceptor atoms. The semiconductor thus formed is called P-type
semiconductor.

17. PN JUNCTION
• If one side of a single crystal of semiconductor is doped with acceptor impurity
atoms and the other side of the same crystal is doped with donor impurity atoms, a
PN Junction is formed. The area where the P-type and N-type regions meet is called
a PN Junction and the resulting device is a diode. The PN Junction is not produced
by simply connecting the P-type and N-type material by welding or other similar
process but through sophisticated chemical technique.
• In the PN Junction, the donor ion is represented by a plus sign because after this,
impurity atom donates an electron, it becomes positive ion. The acceptor ion is
indicated by a minus sign because after this, atom accepts an electron from the
neighboring atom, it becomes negative ion. Ions are immobile in nature but free
charges are mobile in nature.
P layer N layer

18. Formation of Electric Field in PN Junction

20. Flow of Electric Current to Load through External Circuit

21. Construction and Working of a Solar Cell

22. Array
Charge Controller: It is a device to protect the battery from over charging and over
discharging. If over charged electrolyte will be lost, internal heating will occur; voltage
will rise and reduce battery life. Over discharging also damage the battery.

23. Home Electrification

24. Current-Voltage Characteristics of a Solar cell
• The behaviour of a solar cell can be characterized by using three
parameters i.e., the short circuit current (Isc), the open circuit voltage (Voc)
and fill factor.
• Open Circuit Voltage: When the external resistance ‘R’ is very high (mega-
ohms range or infinity), the condition is called ‘Open Circuit’. Under this
condition, there is very less or no current in the circuit. Open circuit
current is zero. The open circuit voltage (Voc) of a solar cell is about 0.5 V
D.C.
• Short Circuit Current: If resistance ‘R’ is reduced gradually and from high
value to low value, the terminal voltage of cell falls and current increases.
This is similar to a short circuit between positive and negative terminal in
which the terminal voltage is zero and current is maximum. This current is
called short circuit current (Isc).
• Fill Factor (FF): The fill factor is the ratio of maximum power a solar cell
can produce (VmIm) to the theoretical limit (Voc Isc) if both voltage and
current are simultaneously at the maximum. It indicates how well a
junction is made in the cell and how low the series resistance has been
made. Solar cell designers strive to increase the ‘FF’ values to minimize
internal losses. ‘FF’ for a good silicon cell is about 0.8.
• Maximum Efficiency (ηmax): It is the defined as the ratio of maximum electric
power output to the incident solar radiation in a solar cell.
• Mathematically, ηmax = (VmIm)/ (Is As)
• Where Is = Incident solar flux and As = Area of cell.

26. Factors affecting the output of a solar cell
• Sun light (Irradiance): Solar cell output depends on the level of light
or solar radiation flux falling on the solar cell surface.
• Temperature of solar cell: Module temperature affects the output
voltage inversely. Higher module temperature reduces the voltage
by 0.04 to 0.1 volts for every one degree Celsius rise in temperature.
Air should be allowed to circulate behind the back of each module
so that its temperature does not rise causing the increase of its
output.

27. Causes for low efficiency of a solar cell
• Solar cell does not operate at the theoretical maximum
efficiency because of several limitations. The efficiency
of a solar cell varies from 12-15 % only. The following
factors limit the efficiency of a solar cell and mentioned
below.
1. Reflection losses at the top surface of the solar cell.
2. Shading due to charge collection grid at the top
surface
3. Incomplete absorption of photon energy due to
limited cell thickness
4. Incomplete use of photon energy in excess of
forbidden energy
5. Collection losses
6. Voltage factor loss
7. Curve of fill factor loss
8. Series and shunt resistance loss

28. Percentage Loss of Efficiency in
a Solar Cell
Sl.No. Factors responsible for loss of efficiency Percentage of loss
1 No photon absorption (photon energy less
than forbidden energy)
23
2 Excess photon energy (photon energy more
than forbidden energy)
33
3 Surface reflection 0.5
4 Voltage factor 18
5 Fill factor 5
6 Shading due to charge collection grid 0.05
7 Collection losses 5
8 Series resistance 0.5
TOTAL LOSS 85.05

29. Applications of Solar
Photovoltaic Conversion
• Solar Lantern
• Solar Street Light
• Solar Fencing
• Solar Pumping System

30. SOLAR PV SYSTEM DESIGN
• EXAMPLE
The base condition of operating two CFLs (18 watt each) and two fans (60 watt each) for 6 hours per day is considered which will
enable to light two rooms as well as two fans which are enough for a drawing room. A PV system design would require information
about what is total load, how many hours one want to run the appliances, which PV module and battery is available for use, what
would be the total cost, how much solar radiation is available, etc.
A solar PV system design can be done in four steps:
Load estimation
Estimation of number of PV panels
Estimation of battery bank
Cost estimation
Steps to design a solar PV
Step 1: Find out the total energy requirement of the system load (total load).
Total load connected to PV panel system
= No. of Units X rating of equipment
= 2 X 18 + 2 X 60 = 156 watts
Total watt-hours rating
= Connected load load ( watts) X operating hours
= 156 X 6 = 936 watt-hours
Step 2 : Find out the number of PV panel required
Actual power output of a PV panel
= Peak power rating X operating factor
= 40 X 0.75 = 30 watt
The power available for end use is less (due to lower combined efficiency of the system)
= Actual power output of a panel X combined efficiency
= 30 X 0.81 =24.3 watts (VA)
= 24.3 watts
Energy produced by one 40 Wp panel in a day
= Actual power output X 8 hours/day (peak equivalent)
= 24.3 X 8 = 194.4 watt- hour
Number of solar panels required to satisfy given estimated daily load( from Step 1)
=Total watt-hour rating (daily load)/ Daily energy produced by a panel
= 936/194.4 = 4.81 = 5 (round figure)

31. Step 3: Find out the battery requirement
Total amp-hour required (total charge to be stored), (battery size should be higher than the actual useful energy due to less
combined efficiency of the system)
=Total watt – hour rating/(Inverter efficiency X Depth of discharge X Battery voltage)
= 936/0.90 X 0.80 X 12 = 108.33
Number of batteries required
=Total amp-hour rating/ Battery rating under use
= 108.33/120= 0.9 =1 (round figure)
Step 4: Find out inverter size
Inverter rating (watts or VA)
Total connected load to PV panel system=156 watts
=156 VA
Inverters are available with the rating of 100, 200,500 VA,etc.
Therefore, the choice of the inverter should be 200 VA.
Cost Estimation of a PV System
Cost of arrays = No. of PV modules X Cost/Module
= 5 X 2800(for a 40Wp panel @ Rs70/Wp)
= Rs 14000
(b) Cost of batteries = No. of Batteries X Cost/Battery
= 1 X 7500
= Rs 7500
(c) Cost of Inverter = No. of Inverters X Cost/Inverter
= 1 X 5000
= Rs 5000
Total cost of system = A + B + C
= 14000 + 7500 + 5000
= Rs 26500
Additional cost of wiring may be taken as 5% of the total system (Rs. 1325/-)
Total Cost = Rs. 27,825/-

32. Water Pumping
Design of a PV system for pumping 25000 litres of water everyday from a depth of about 10 metre is considered.
The data required for calculation and the steps of calculation are:
Amount of water to be pumped per day= 25000 litre=25 m3
Total vertical lift= 12 metres (5m-elevation,5 m-standing water level, 2m-drawdown)
Water density= 1000 kg/m3
Acceleration due to gravity, g= 9.8 m/s2
Solar PV module used= 75 wp
Operating factor= 0.75 (PV panel mostly does not operate at peak rated power)
Pump efficiency= 30% or 0.30
Mismatch factor= 0.85
Calculations for PV water pumping system
Step 1: Determination total daily water requirement
Daily water requirement = 25 m3/day
Step 2: Determination total dynamic head
Total vertical lift= 12 m
Frictional losses= 5% of the total vertical lift
= 12 X 0.05 = 0.6 metre
Total dynamic head (TDH) = 12 + 0.6 =12.6 m
Step 3: Determine the hydraulic energy required per day
Hydraulic energy required to raise water level
= Mass X g X TDH
= density X volume X g X DH
= (1000 kg/m3) X (25 m3/day) X (9.8 m/s2) X 12.6
= (multiply by 1/3600 to convert second in hours)
= 857.5 watt-hour/day

33. Step 4: Determine the number of PV panels and pump size
Total wattage of PV panel
= Total hydraulic energy
No. of hours of peak sunshine/day
= 857.5/6 = 142.9 watt
Considering system losses
=Total PV panel wattage/Pump efficiency X Mismatch factor
= 142.9/0.3 x 0.85 = 560 watt
Considering operating factor for PV panel
= Total PV panel wattage after losses/Operating factor
= 560/0.75 = 747.3 watt
Number of 75 Wp solar PV panels required
= 747.3/75 = 9.96 =10 (round figure)
Power rating of the motor
= 747.3/746 = 1 HP water
In this way, a solar PV water pumping system can be designed. The above design has been done
assuming the use of a DC motor. A system, can also be designed for an AC motor but one must
consider inverter and its efficiency in the calculations. Also, the cost of the solar PV irrigation
system can be estimated by considering the individual component cost, e.g. cost of solar panel,
cost of motor and cost of pump and wiring cost.

34. Numerical-3
Design of a PV system for pumping 25000 litres of water every day from a depth of about 10 metre is considered.
The data required for calculation and the steps of calculation are:
•Amount of water to be pumped per day= 25000 litre=25 m3
•Total vertical lift= 12 metres (5m-elevation,5 m-standing water level, 2m-drawdown)
•Water density= 1000 kg/m3
•Acceleration due to gravity, g= 9.8 m/s2
•Solar PV module used= 75 wp
•Operating factor= 0.75 (PV panel mostly does not operate at peak rated power)
•Pump efficiency= 30% or 0.30 (can be taken between 0.25 and 0.4).
Mismatch factor= 0.85 (PV panel does not operate at maximum powe
Calculations for PV water pumping system
Step 1: Determination total daily water requirement
Daily water requirement = 25 m3/day
Step 2: Determination total dynamic head
Total vertical lift= 12 m
Frictional losses= 5% of the total vertical lift
= 12 X 0.05 = 0.6 metre
Total dynamic head (TDH) = 12 + 0.6 =12.6 m
Step 3: Determine the hydraulic energy required per day
Hydraulic energy required to raise water level
= Mass X g X TDH
= density X volume X g X TDH
= (1000 kg/m3) X (25 m3/day) X (9.8 m/s2) X 12.6 m
= (multiply by 1/3600 to convert second in hours)
= 857.5 watt-hour/day
Potential energy of the water is raised due to pumping, which must be supplied to the pump.

35. Step 4: Determine solar radiation data
Solar radiation data in terms of equivalent peak sunshine radiation (1000 W/m2) varies between about 4 and 7 hours.
For exact hours meteorological data should be used.
= 6 hours/day (peak of 1000W/m2 equivalent), actual day length is longer (this is equivalent of solar radiation of 180000 watt-hours/month
at a given location)
Step 5: Determine the number of PV panels and pump size
Total wattage of PV panel
= (Total hydraulic energy) / (No. of hours of peak sunshine/day) = 857.5/6 = 142.9 watt
Considering system losses =Total PV panel wattage/Pump efficiency X Mismatch factor
= 142.9/(0.3 x 0.85) = 560 watt
Considering operating factor for PV panel
= Total PV panel wattage after losses/Operating factor
= 560/0.75 = 747.3 watt
Number of 75 Wp solar PV panels required
= 747.3/75 = 9.96 =10 (round figure)
Power rating of the motor
= 747.3/746 = 1 HP water
In this way, a solar PV water pumping system can be designed. The above design has been done assuming the use
of a DC motor. A system can also be designed for an AC motor but one must consider inverter and its efficiency in the calculations.
Also, the cost of the solar PV irrigation system can be estimated by considering the individual component cost, e.g. cost of solar panel,
cost of motor and cost of pump and wiring cost.

36. Numerical-4 Calculate the no module (each module of 40 W output) required for supplying power
to operate a pump 60% efficiency if 60 m3 of water to be lifted at a height of 5 m in a period of 4 hours.
time
vgh

     W
hour
hour
m
s
m
m
m
Kg
16
.
204
sec/
3600
4
5
/
8
.
9
60
/
1000 2
3
3


W
W 360
340
6
.
0
16
.
204


9
40
360


Solution: The potential energy is to be given to a mass of water (work) W=PE = mgh
Mass = Density x Volume, so W =ρvgh
Power =
=
Pump efficiency = 60%
Power =
Modules

37. Solar Lantern
Applications and uses
Emergency and/or house lighting, table lamp, camping, patrolling (streets, farms),
Hawker / Vendor Stalls, non-electrified remote places: Adult education, mass
communication. Easy and convenient alternative to kerosene / petromax / gas.
Benefits
It is easy to install, no electrical connection is required and no electricity charges.
Lantern is made of three main components - the solar PV panel, the storage battery
and the lamp. The lamp, battery and electronics all placed in a suitable housing
made of metal, plastic or fiber glass.
A single charge can operate the lamp for about 4-5 hours. The lantern is basically a
portable lighting device suitable for either indoor or outdoor lighting,

38. Solar Street Lighting System
1. SPV Module
2. Battery Box
3. Lamp with charge controller
4. Lamp Post
The solar street light system comprise of
a) 74 Wp Solar PV Module
b) 12 V, 75 Ah Tubular plate battery with
battery box
c) Charge Controller cum inverter (20-35 kHz)
d) 11 Watt CFL Lamp with fixtures
e) 4 metre mild steel lamp post above ground
level with weather proof paint and mounting
hardware.

39. Solar Fencing
• The electric fencing system works by taking power from solar
energy. There is a battery bank provided due to which the system
runs uninterruptedly during nights and cloudy days.
High Security Fence
Security Fence
Animal Fence
Agriculture Fence
The impulse carries 10 mA of current and delivers
a shock lasting for a fraction of a second. The
batteries can be recharged using readymade solar
fence chargers. Battery operated solar fences
may cost from INR45,000-50,000 per acre (4000
m2). Cheaper versions costing as low as
INR10,000-25,000 per acre have been developed
using locally made materials in some places in
India.
•It gives a short, sharp but safe shock to the intruder.
•High voltage and very low current generation and Perimeter
protection

41. The basic building blocks of solar fence
• Energizer 2. Earthing (Grounding System)
and 3. Fence system
Features of solar fencing system
a) Easy Construction.
b) Power fence can be erected to target species only.
c) Low maintenance.
d) Long lasting because of minimal physical pressure.
e) All domestic and wild animals can be controlled economically.
f) Makes strip grazing and back fencing easy.
g) Encourages additional subdivision, giving increased production.
h) Modification of system to control a variety of animals is very easy.
i) Aesthetically pleasing.
j) Discourages trespassers and predators.
k) Not harmful. It gives a short, sharp but safe shock to the intruder.
l) Perimeter protection

42. Solar Pumping System
Advantages of solar pump sets
a) No fuel cost-uses abundantly available
free sun light
b) No conventional grid electricity required
c) Long operating life
d) Highly reliable and durable- free
performance
e) Easy to operate and maintain
f) Eco-friendly
g) Saving of conventional diesel fuel
The solar water pumping system is a stand-alone system operating on power
generated using solar PV (photovoltaic) system. The power generated by solar
cells is used for operating DC surface centrifugal mono-block pump set for
lifting water from bore / open well or water reservoir for minor irrigation and
drinking water purpose.

43.  The system is provided with 1800 W solar PV panel (24 nos. X 75 Wp)
and 2 HP centrifugal DC mono-block / AC submersible with
inverter. The average water delivery of 2 HP solar pump will be around
1.38 to 1.40 lakh litre per day, for a suction head of 6 metres and
dynamic head of 10 metres. The size of suction & delivery lines is 2.5
inches (62.5 mm).

45. SOLAR PHOTOVOLTAIC POWER PLANT

46. WHAT IS A ROOFTOP SOLAR POWER PLANT
• A roof top solar power plant is an array of solar photovoltaic
modules consisting of small solar cells that convert sunlight into
electricity which can be consumed during the day or stored in
batteries for the night.
• Since the power generated is in DC mode, it requires an inverter to
get AC power to suit the consumption requirements and connect it
to the main user load
• Depending upon the orientation of the roof top, about 120-150
square foot shadow free roof space is required for each kW of solar
power plant.
• Each kW capacity of solar power plant provides 4-5 units (1 unit = 1
kWh) of power on a clear sunny day.
• Life of the system is about 25 years and requires very less
maintenance
• It is a passive power generator with no moving parts. Since sun
light is the only fuel it uses, care should be taken such that
adequate sunlight falls on modules

47. WHY ROOF TOP SOLAR PHOTOVOLTAIC SYSTEM
• It reduces dependence of land space
• Unused space of roof top of the house be utilized
• Better availability of sunlight in roof top compared to land space on
ground
• Reduces the dependence of grid power
• Long term reliable power source
• Transmission and distribution losses are minimized as power is
consumed at the point of generation
• Avoids the use of diesel generator during power cut-off
• Small scale set-up in rural areas for water pumping of drinking
water and watering for kitchen gardening
• Most suitable for commercial establishment
• Government subsidy (30 % of total cost) is available
• Government initiatives for popularization through Jawaharlal Nehru
National Solar Mission
• Capacity may vary from 0.5 kW to 2 kW at individual level

48. Growth of Solar Capacity
(MW)

50. ROOF TOP PV POTENTIALS OF INDIA
According 2011 Census India is having
 330 million houses.
 166 million electrified houses.
 76 million houses uses kerosene for lighting.
 1.08 million houses are using solar for lighting.
 140 million houses with proper roof (Concrete or Asbestos
/ metal sheet).
 130 million houses are having > 2 rooms.
 Average house can accommodate 1-3 kW of solar PV
system.
 The large commercial roofs can accommodate larger
capacities.
 As a conservative estimate, about 25000 MW capacity can
be accommodated on roofs of buildings having > 2 rooms
alone if we consider 20% roofs.

51. COST ESTIMATE OF SMALL SCALE ROOF
TOP SOLAR PV SYSTEM
Capacity
of PV
solar
plant (kW)
Requirement of
space (sq. ft.)
Average
output/day
(units)
Approx.
cost of
system
(Rs.
Lakh)
Subsidy
(Rs. Lakh)
Cost to
user
(Rs.
Lakh)
Life of
system
(years)
Total
income
during life
span
(lakhs)
Total
expenditure
on
maintenance(
Rs.)
Pay back
periods
(years)
(house
hold load
and
water
pumping
)
0.5 60-75 1.75 0.75 0.225 0.525 25 1.3 1500 4 to 5
1 120-150 3.5 1.5 0.45 1.05 25 2.6 3000 4 to 5
1.5 180-200 5.25 2.25 0.675 1.575 25 3.9 4500 4 to 5
2 240-300 7 3 0.9 2.1 25 5.2 6000 4 to 5

52. BENEFITS AND PAY BACK OF 0.5 kW CAPACITY ROOF
TOP SOLAR PV SYSTEM WITH SUPPLYING HOUSE
LOADS AND WATERING FOR KITCHEN GARDENING
Cost Estimate for 0.5 kW Capacity Solar PV
System
• Solar PV Module of 500 watt @ Rs. 50 per wp = Rs. 25,000
• Inverter = Rs. 10,000
• Battery = Rs. 20,000
• Accessories = Rs. 5, 000
TOTAL = Rs. 60,000
Availing 30 percent Govt. subsidy (-Rs. 18,000) Net Cost = Rs. 42,000
• Water pump (0.5 hp) = Rs. 5,000
• Tube well = Rs. 20,000
• Overhead water tank = Rs. 10,000
• Drip irrigation set up (1/5th acre)= Rs. 8,000

53. BENEFIT-COST ESTIMATION (1/5TH ACRE KITCHEN
GARDENING WITH DRIP IRRIGATION SYSTEM)
• 0.5 kW = 500 watt x 5 sunny hours/day x 25 sunny days/month x 12
= 750 kWh/year = 750 units of electricity x Rs 5/unit = Rs. 3750/year
• Cost of cultivation of vegetable in 1/5th acre land = Rs. 5000
• Yield of vegetable from 1/5th acre land = 6 quintals
• Cost of vegetable @Rs. 20/kg = Rs. 12,000
• Net gain = Rs. 12000-5000 = Rs. 7,000/season
• Considering two seasons cultivation, net gain = Rs. 14,000/year
• Total income from roof top PV system with 750 units of electricity
= Rs. 14,000 + Rs. 3750 = 17,750
• Yearly expenditure on maintenance = Rs. 1500
• Net annual income = Rs. 17, 750 – Rs. 1500 = Rs. 16, 250
• Pay back period (year) = (Total expenditure) / (Net annual income)
= 85,000/16250 = 5.2 = 5 years
• After 5 years, the system is practically free for use with income of
about Rs. 1500/month

54. ENVIRONMENTAL BENEFIT FROM ADOPTION
OF ROOF TOP SOLAR PHOTOVOLTAIC SYSTEM
• From 1 kW solar PV system, 120 units of electricity will
be generated in a month and about 1400 units of
electricity in a year
• The average carbon dioxide emission for electricity
generation from coal based thermal power plant is
approximately 0.98kg of CO2 per kWh at the source. If
the transmission and distribution losses for Indian
condition are taken as 40% and poor inefficient electric
equipment losses are around 20%, then figure 0.98 can
be taken as1.58 kg/kWh
• Atmospheric carbon dioxide load can be reduced by 2.2
tons/year
• Considering 20 % of roofs of 130 million houses in
India having more than 2 rooms, annual CO2 load to
atmosphere can be reduced by about 60 million tones
• This would ultimately help in mitigating greenhouse
gases emission and climate change problems