SOLAR ENERGY - FARM POWER REPORT AE 215

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DEPARTMENT OF ENGINEERING SCIENCES AND TECHNOLOGY
Bsc. Irrigation and Water Resources Engineering
GROUP 02-Assignment
AE 215: SOURCES OF FARM POWER
SOLAR ENERGY
SOKOINE UNIVERSITY OF
AGRICULTURE
INSTRUCTOR: Dr. PROCHES HIERONIMO
DATE OF SUBMISSION: 15th
may 2018
2018

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LIST OF MEMBERS
S/N NAME OF A STUDENT REG. NUMBER SIGNATURE
1. DOTO,MUSA GESE IWR/D/2016/0011
2. MBEPERA PIRIMINI REMIGIUS IWR/D/2016/0034
3. SELEMANI, SHANI JUMANNE IWR/D/2016/0071
4. MABELE ZACHARIA IWR/D/2016/0028
5. BARNABAS EDWARD IWR/D/2016/0006
6. KAYUMBO CHARLES J IWR/D/2016/0018
7. DAMIANO FADHIL P IWR/D/2016/0069
8. MRISHO,MSHAMU M IWR/D/2016/0036
9. KOYI PERIS J IWR/D/2016/0021
10. LODARU , SHEDRACK B IWR/D/2016/0025
11. MABULA , NDAHYA IWR/D/2016/0029
12. ABEL MASUMBUKO IWR/D/2016/0001
13. NYALUTOGO BENJAMINI E IWR/D/2016/0047
14. PAUL SILAS M IWR/D/2016/0050
15. UFINYU FREDRICK M IWR/D/2016/0057
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TABLE OF CONTENTS
1. INTRODUCTION …………………………………………………….. 2
2. APPLICATIONS……………………………………..………………... 4
3. FACTORS AFFECTING SOLAR POWER SYSTEM ……………. 9
4. SOLAR COLLECTORS ………………………………………….. ....11
5. PHOTOVOLTAIC CELL …………………………………………… 20
6. SOLAR ENERGY COMPONENTS SYSTEM …………………….. 24
7. SOLAR ENERGY IN TANZANIA…………………………………...28
8. GENERAL VIEW…………………………………………………….. 31
REFERENCE …………………………………………………………32
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1. INTRODUCTION
1.1 What is solar energy?
The sun has been used for drying clothes and growing food for thousands of years, but
only recently has the sun been used for solar power. Concerns over pollution,
environmental degradation, and resource depletion have led to an increasing awareness
of the importance of developing solar energy. Just the tiny fraction of the sun's energy
that hits the Earth (around a hundredth of a millionth of a percent) is enough to meet all
our power needs many times over. In fact, every minute, enough energy arrives at the
Earth to meet our demands for a whole year - if only we could harness it properly.
Solar energy is quite simply the energy produced directly by the sun and collected
elsewhere, normally the Earth. The sun creates its energy through a thermonuclear
process that converts about 650,000,000 tons of hydrogen to helium every second. The
process creates heat and electromagnetic radiation. The heat remains in the sun and is
instrumental in maintaining the thermonuclear reaction. The electromagnetic radiation
(including visible light, infra-red light, and ultra-violet radiation) streams out into
space in all directions. Only a very small fraction of the total radiation produced
reaches the Earth. The radiation that does reach the Earth is the indirect source of
nearly every type of energy used today. The exceptions are geothermal energy, and
nuclear fission and fusion. Even fossil fuels owe their origins to the sun; they were
once living plants and animals whose life was dependent upon the sun.
1.2 History of solar power (nature and its origin).
With the recent rise in energy costs many people have been looking to alternative
sources of energy. One of the greatest energy sources (our sun) is readily available for
the taking. We just need to be able to harness it‟s power. For those interested, below is
a brief history of how solar power came to be. The history of photovoltaic energy (aka.
solar cells) started way back in 1876. William Grylls Adams along with a student of
his, Richard Day, discovered that when selenium was exposed to light, it produced
electricity. An electricity expert, Werner von Siemens, stated that the discovery was
“scientifically of the most far-reaching importance”. The selenium cells were not
efficient, but it was proved that light, without heat or moving parts, could be converted
into electricity. In 1953, Calvin Fuller, Gerald Pearson, and Daryl Chapin,

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discovered the silicon solar cell. This cell actually produced enough electricity and was
efficient enough to run small electrical devices. The New York Times stated that this
discovery was “the beginning of a new era, leading eventually to the realization of
harnessing the almost limitless energy of the sun for the uses of civilization.” The year
is 1956, and the first solar cells are available commercially. The cost however is far
from the reach of everyday people. At $300 for a 1 watt solar cell, the expense was far
beyond anyone‟s means. 1956 started showing us the first solar cells used in toys and
radios. These novelty items were the first item to have solar cells available to
consumers. In the late 1950‟s and early 1960‟s satellites in the USA‟s and Soviet‟s
space program were powered by solar cells and in the late 1960‟s solar power was
basically the standard for powering space bound satellites. In the early 1970‟s a way to
lower to cost of solar cells was discovered. This brought the price down from $100 per
watt to around $20 per watt. This research was spearheaded by Exxon. Most off-shore
oil rigs used the solar cells to power the warning lights on the top of the rigs. The
period from the 1970‟s to the 1990‟s saw quite a change in the usage of solar cells.
They began showing up on railroad crossings, in remote places to power homes,
Australia used solar cells in their microwave towers to expand their telecommunication
capabilities. Even desert regions saw solar power bring water to the soil where line fed
power was not an option. Today we see solar cells in a wide variety of places. You
may see solar powered cars. There is even a solar powered aircraft that has flown
higher than any other aircraft with the exception of the Blackbird. With the cost of
solar cells well within everyone‟s budget, solar power has never looked so tempting.
Recently new technology has given us screen printed solar cells, and a solar fabric that
can be used to side a house, even solar shingles that install on our roofs. International
markets have opened up and solar panel manufacturers are now playing a key role in
the solar power industry.

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2. APPLICATIONS OF SOLAR ENERGY
Some of the major applications of solar energy are as follows:
1. Solar water heating
2. Solar heating of buildings
3. Solar distillation
4. Solar pumping
5. Solar drying of agricultural and animal products
6. Solar furnaces
7. Solar cooking
8. Solar electric power generation
9. Solar thermal power production
10.Solar green houses
SOLAR WATER HEATING
A solar water heating unit comprises a blackened flat plate metal collector with an
associated metal tubing facing the general direction of the sun. The plate collector
has a transparent glass cover above and a layer of thermal insulation beneath it.
The metal tubing of the collector is connected by a pipe to an insulated tank that
stores hot water during cloudy days. The collector absorbs solar radiations and
transfers the heat to the water circulating through the tubing either by gravity or by
a pump. This hot water is supplied to the storage tank via the associated metal
tubing. This system of water heating is commonly used in hotels, guest houses,
tourist bungalows, hospitals, canteens as well as domestic and industrial units.
SOLAR HEATING OF BUILDINGS
Solar energy can be used for space heating of buildings in many ways namely:
1 Collecting the solar radiation by some element of the building itself i.e. solar
energy is admitted directly into the building through large South-facing
windows.
2 Using separate solar collectors which may heat either water or air or storage
devices which can accumulate the collected solar energy for use at night and
during inclement days. When the building requires heat then from these
collectors or storage devices, the heat is transferred by conventional
equipment such as fan, ducts, air out lets, radiators and hot air registers, to
warm up the living spaces of a building.

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SOLAR-DISTILLATION
In semi arid and or coastal areas there is scarcity of potable water. The abundant
sunlight in these areas can be used for converting saline water into potable distilled
water by the method of solar distillation. In this method, solar radiation is admitted
through a transparent air tight glass cover into a shallow blackened basin
containing saline water. Solar radiation passes through the covers and is absorbed
and converted into heat in the blackened surface causing the water to evaporate
from the brine (impure saline water). The vapors produced get condensed to form
purified water in the cool interior of the roof. The condensed water flows down the
sloping roof and is collected in the troughs placed at the bottom and from there into
a water storage tank to supply potable distilled water in areas of scarcity, in
colleges, school science laboratories, defense labs, petrol pumps, hospitals and
pharmaceutical industries. Per liter distilled water cost obtained by this system is
cheaper than distilled water obtained by other electrical energy-based processes.
SOLAR-PUMPING
In solar pumping, the power generated by solar-energy is utilized for pumping
water for irrigation purposes. The requirement for water pumping is greatest in the
hot summer months which coincide with the increased solar radiations during this
period and so this method is most appropriate for irrigation purpose. During
periods of inclement weather when solar radiations are low then the requirement
for water pump ing is also relatively less as the transpiration losses from the crops
are also low.
SOLAR FURNACES
In a Solar furnace, high temperature is obtained by concentrating the solar
radiations onto a specimen using a number of heliostats (turn-able mirrors)
arranged on a sloping surface. The solar furnace is used for studying the proper ties
of ceramics at extremely high temperatures above the range measurable in
laboratories with flames and electric currents. Heating can be accomplished
without any contamination and temperature can be easily controlled by changing
the position of the material in focus. This is especially useful for metallurgical and
chemical operations. Various property measurements are possible on an open
specimen. An important future application of solar furnaces is the production of
nitric acid and fertilizers from air.

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SOLAR DRYING OF AGRICULTURAL AND ANIMAL PRODUCTS
This is a traditional method of utilizing solar energy for drying of agricultural and
animal products. Agricultural products are dried in a simple cabinet dryer which
consists of a box insulated at the base, painted black on the inner side and covered
with an inclined transparent sheet of glass. At the base and top of the sides
ventilation holes are provided to facilitate the flow of air over the drying material
which is placed on perforated trays inside the cabinet. These perforated trays or
racks are carefully designed to provide controlled exposure to solar radiations.
Solar drying, especially of fruits improves fruit quality as the sugar concentration
increases on drying. Normally soft fruits are particularly vulnerable to insect attack
as the sugar content increases on drying but in a fruit dryer considerable time is
saved by quicker drying - minimizing gap the chances of insect attack. The present
practice of drying chilies by spreading them on the floor not only requires a lot of
open space and manual labour for material handling but it becomes difficult to
maintain its quality and taste unless drying is done in a controlled atmosphere.
Moreover, the products being sun dried very often get spoiled due to sudden rains,
dust storms or by birds. Besides, reports reveal that it is not possible to attain very
low moisture content in the sun-dried chilies. As a result, the chilies become prone
to attack by fungi and bacteria. In sun-drying sometimes, the produce is over dried
and its quality is lost. Solar energy operated dryer helps to overcome most of these
disadvantages. Other agricultural products commonly solar-dried are potato-chips,
berseem, grains of maize and paddy, ginger, peas, pepper, cashew-nuts, timber and
veneer drying and tobacco curing. Spray drying of milk and fish drying are
examples of solar dried animal products.
SOLAR COOKING
A variety of fuel like coal, kerosene, cooking gas, firewood, dung cakes and
agricultural wastes are used for cooking purposes. Due to the energy crisis, supply
of these fuels are either deteriorating (wood, coal, kerosene, cooking gas) or are
too precious to be wasted for cooking purposes (cow dung can be better used as
manure for improving soil fertility). This necessitated the use of solar energy for
cooking purposes and the development of solar cookers. A simple solar cooker is
the flat plate box type solar cooker. It consists of a well-insulated metal or wooden
box which is blackened from the inner side. The solar radiations entering the box
are of short wavelength. As higher wave length radiations are unable to pass

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through the glass covers, the re-radiation from the blackened interior to outside the
box through the two glass covers is minimized, thereby minimizing the heat loss.
The heat loss due to convection is minimized by making the box airtight. This is
achieved by providing a rubber strip between the upper lid and the box for
minimizing the heat loss due to conduction, the space between the blackened tray
and outer cover of the box is filled with an insulting material like glass wool, saw-
dust, paddy husk. When placed in sunlight, the solar rays penetrate the glass covers
and are absorbed by the blackened surface thereby resulting in an increase in
temperature inside the box. Cooking pots blackened from outside are placed in the
solar box. The uncooked food gets cooked with the heat energy produced due to
increased temperature of the solar box. Collector area of such a solar cooker can be
increased by providing a plane reflector mirror. When this reflector is adjusted to
reflect the sun rays into the box, then a 15°C to 25°C rise in temperature is
achieved inside the cooker box. The solar cooker requires neither fuel nor attention
while cooking food and there is no pollution, no charring or overflowing of food
and the most important advantage is that nutritional value of the cooked food is
very high as the vitamins and natural tastes of the food are not destroyed.
Maintenance cost of the solar cooker is negligible. The main disadvantage of the
solar cooker is that the food cannot be cooked at night, during cloudy days or at
short notice. Cooking takes comparatively more time and Chapattis cannot be
cooked in a solar cooker.
SOLAR ELECTRIC POWER GENERATION
Electric energy or electricity can be produced directly from solar energy by means
of photovoltaic cells. The photovoltaic cell is an energy conversion device which
is used to convert photons of sunlight directly into electricity. It is made of semi-
conductors which absorb the photons received from the sun, creating free electrons
with high energies. These high energy free electrons are induced by an electric
field, to flow out of the semiconductor to do useful work. This electric field in
photovoltaic cells is usually provided by a p-n junction of materials which have
different electri cal properties. There are different fabrication techniques to enable
these cells to achieve maximum efficiency. These cells are arranged in parallel or
series combination to form cell modules. Some of the special features of these
modules are high reliability, no expenditure on fuel, minimum cost of
maintenance, long life, portability, modularity, pollution free working etc.
Photovoltaic cells have been used to operate irrigation pumps, rail road crossing
warnings, navigational signals, highway emergency call systems, automatic
meteorological stations etc. in areas where it is difficult to lay power lines. They
are also used for weather monitoring and as portable power sources for televisions,

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calculators, watches, computer card readers, battery charging and in satellites etc.
Besides these, photovoltaic cells are used for the energisation of pump sets for
irrigation, drinking water supply and for providing electricity in rural areas i.e.
street lights.
SOLAR THERMAL POWER PRODUCTION
Solar thermal power production means the conversion of solar energy into
electricity through thermal energy. In this procedure, solar energy is first utilized to
heat up a working fluid, gas, water or any other volatile liquid. This heat energy is
then converted into mechanical energy m a turbine. Finally a conventional
generator coupled to a converts this mechanical energy into electrical energy.
Production of Power through Solar Ponds:
A solar pond is a natural or artificial body of water utilized for collecting and
absorbing solar radiation and storing it as heat. It is very shallow (5-10 cm
deep) and has a radiation absorbing (black plastic) bottom. It has a curved
fibre glass cover over it to permit the entry of solar radiation but reduces
losses by radiation and convection (air movement). Loss of heat to the
ground is minimized by providing a bed of insulating material under the
pond. Solar ponds utilize water for collecting and storing the solar energy
which is used for many applications such as space heating, industrial process
heating and to generate electricity by driving a turbine powered by
evaporating an organic fluid with a low boiling point.
SOLAR GREEN HOUSES
A green house is a structure covered with transparent material (glass or plastic) that
acts as a solar collector and utilizes solar radiant energy to grow plants. It has
heating, cooling and ventilating devices for controlling the temperature inside the
green house. Solar radiations can pass through the green house glazing but the
thermal radiations emitted by the objects within the green house cannot escape
through the glazed surface. As a result, the radiations get trapped within the green
house and result in an increase in temperature. As the green house structure has a
closed boundary, the air inside the green house gets enriched with CO as there is
no mixing of the greenhouse air with the ambient air. Further, there is reduced
moisture loss due to restricted transpiration. All these features help to sustain plant
growth throughout the day as well as during the night and all year round.

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3. FACTORS AFFECTING SOLAR POWER SYSTEM
1. TEMPERATURE
The solar cells perform better in cold rather than in hot climate and as things
stand panels are rated at 25o
c which can be significantly different from the
real outdoor situation. For each degree rise in temperature above 25o
c the
panel output decays about 0.25% for amorphous cells and about 0.4%-0.5%
for crystalline cells. Thus in hot summer day‟s panel temperature can easily
reach 700
c or more. What it means is that the panels will put up to 25% less
power compared to what they are rated for at 25o
c.
2. CABLE THICKNESS
We generally have electrical appliances working at 220V which is
significantly higher compared with the usual PV system DC voltages of
12V, 24V or 48V. For the same wattage much higher currents area involved
in the PV systems. This brings into picture resistance losses in wiring.
Let us see how it can be significant. 20 meter is the length of a cable
between the panel and the charge controller. A typical cable with 1.5sq mm
cross section has a resistance of about 0.012 ohms per meter of a wire
length. So a 20 meter long wire will offer resistance of 20 x 0.012=0.24
ohms.
3. SHADING
Ideally solar panels should be located such that there will never be shadows
on them because a shadow on even a small part of the panel can have a
surprisingly large effect on the output. The cell within a panel are normally
all wired in series and the shaded cells affect the current flow of the whole
panel. But there can be situations where it cannot be avoided, and thus the
effects of partial shading should be considered while planning. If the
affected panel is wired in series (in a string) with other panels will be
affected by the partial shading of one panel. In such situation is to avoid
wiring panels in series if possible.

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4. BATTERY EFFICIENCY
Whenever backup is required batteries are needed for charge storage. Lead
acid batteries are most commonly used. All batteries are most commonly
used. All batteries discharged less than what go into them; the efficiency
depends on the battery design and quality of construction; some are certainly
more efficient than others. The energy put in a battery during charging Ein
can be given as EIN = ICVC ∆TC where IC is the constant charge at voltage
VC for time duration ∆TC .
5. INVERTER EFFICIENCY
When the solar PV system is catering to the needs of the AC loads an
inverter is needed. As things stand, in real world nothing is 100% efficient.
Although inverters come with wide ranging efficiencies but typically
affordable solar inverters are between 80% to 90% efficient.
6. CHARGE CONTROLLERAND SOLAR CELL’
S CHARACTERISTICS
An inherent characteristic of solar silicon cells is that the current produced
by a particular light level is virtually constant up to a certain voltage (about
0.5V for silicon) and then drops off abruptly. What it means is that mainly
the voltage varies with light intensity. A solar panel with nominal voltage of
12 volts would normally have 36cells, resulting in a constant current up to
about 18 volts. Above this voltage, current drops off rapidly, resulting in
maximum power output being produced at around 18 volts. When the panel
is connected to the battery through a simple charge regulator, its voltage will
be pulled down to near that of the battery. This lead to lower watt power
(watt = Amp x Volt) output from the panel. Thus, the panel will be able to
produce its maximum power when the battery voltage is near its maximum
(fully charged). So it helps to design a system in such as way that the
batteries normally don‟t remain less than full charged for long. In times of
rainy or heavy clouded days a situation may occur when the batteries remain
in the state of less than full charge. This would further pull down the panel
voltage; thus degrading the output further.

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4. SOLAR COLLECTORS
Solar collector
Is a mechanical device which captures the radiant solar energy and converts it to
useful thermal energy. Solar collectors transform solar radiation into heat and
transfer that heat to a medium (water, solar fluid, or air). Then solar heat can be
used for heating water, to heating or cooling systems, or for heating swimming
pools. Solar cooling technologies (chemical, electrical and thermal processes)
demand high temperatures and not all the type of solar collectors are capable of
producing them. The collectors needed are based on technologies, which can
supply hot water at relatively high temperature (90-1500
C).
Conditions of active solar thermal collectors
Low density per unit area (1kW/m2
– 0.1kW/m2
)
Collected by covering large area
Solar energy as heat
Transfer to heat transport fluid
Thermal storage tank/boiler/heat exchanger
 Are Both beam and diffused radiation
 Insulated so as to reduce heating or cooling loss
TYPES OF SOLAR COLLECTORS
(i) Flate-plate collector
(ii) Evacuated or (vacuum) tube collector
(iii) Concentrating collector
(iv) Pool collector
(v) Tank-type collector
FLAT-PLATE COLLECTOR
Flat-plate collectors are the most widely used kind of collectors in the world for
domestic water-heating systems and solar space heating/cooling. The first accurate
model of flat plate solar collectors was developed by Hottel and Whillier in the
1950's. These collectors are used typically for temperature requirements up to 750
C
but high efficiency collectors can used up to temperature of 1000
C.

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Components and mode of working of Flat-plate collector
A typical flat-plate collector consists of an absorber, transparent cover
sheets, and an insulated box. “The absorber is usually a sheet of high-
thermal conductivity metal such as copper or aluminum, with tubes either
integral or attached. Its surface is coated to maximize radiant energy
absorption and to minimize radiant emission. The insulated box reduces
heat loss from the back or the sides of the collector. The cover sheets, called
glazing, allow sunlight to pass through the absorber but also insulate the
space above the absorber to prevent cool air to flow into this space.

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Flat-plate collectors are classified into 2 basic types namely
liquid type
Air type
Both Flat-plate collector types are planed on the top of building or the
structures and also are durable and effective.

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EVACUETED OR (VACUUM) TUBE COLLECOR
Evacuated (or Vacuum) Tubes are solar panel built to reduce convective and
heat conduction loss (vacuum is a heat insulator). Different construction
types are available
Heat pipes or direct flow
All glass tubes
With or without concentrator
It use when it necessary high temperature of fluid

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Components and mode of working of Glass evacuated tubes
Glass evacuated tubes are the key component of the Evacuated Tube Heat
Pipe solar collectors. Each evacuated tube consists of two glass tubes. The
outer tube is made of extremely strong transparent borosilicate glass that is
able to resist impact from hail up to 25mm in diameter. The inner tube is
also made of borosilicate glass, but coated with a special selective coating,
which features excellent solar heat absorption and minimal heat reflection
properties.
The manifold is heavily insulated with a 2" thickness of pre-formed rock
wool to keep the heat in. Unlike flat plates, these headers are so well
insulated that they should not require antifreeze in normal operation- the
temperature of the header is unlikely to fall below 10°C even in very cold
weather. The air is evacuated from the space between the two glass tubes to
form a vacuum, which eliminates conductive and convective heat loss. The
vacuum tube solar panel has been around for several years and has proved to
be both reliable and dependable. The double wall glass tubes (made from
strong borosilicate glass i.e. Pyrex) have a space in the center which contains
the heat pipe.
The sun's radiation is absorbed by the selective coating on the inner glass
surface, but is prevented from re-radiating out by the silver-coated innermost
lining which has been optimized for infrared radiation This acts similarly as
an one-way mirror. This is very efficient. 93% of the sun light's energy
hitting the tube's surface, is absorbed, whereas only 7% is lost through
reflection and re-emission. The presence of the vacuum wall prevents any
losses by conduction or convection - just like a thermos flask. Because of

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this, the system will work even in very low temperatures, unlike traditional
flat plate collectors.The heat transferred to the tip of the heat pipe is in turn
transferred to a copper manifold in which water circulates to heat the
domestic hot water tank. If a tube is placed in direct sunlight on a summer
day, the tip temperature can reach 250°C - so the system easily heats
domestic hot water cylinders to 60°C even in cooler weather.
CONCENTRATING COLLECTORS
A concentrating collector utilizes a reflective parabolic-shaped surface to reflect
and concentrate the sun‟s energy to a focal point or focal line where the absorber is
located. Solar collector use radiation concentration when wont fluid temperature
more than 100°C radiation concentration can be static or dynamic. This collector
use stationary radiation concentration;
It‟s usually used to heat liquid (water or water with antifreeze or diathermic fluid).
It can be used for domestic hot water preparation and can be used in Solar cooling.
In this panel there is a reduction of convective losses.

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Cylindrical parabolic concentrator
Parabolic dish
Modified flat plate
Fixed mirror solar concentrator
Hemispherical bowl
Compound parabolic concentrating mirror collector
Linear Fresnel lens collector
Circular Fresnel lens collector
Central tower receiver
Cylindrical Parabolic Concentrator
CONCENTRATING TYPE
FOCUS TYPE POINT FOCUS NON-FOCUS

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Parabolic Dish Collector
Central Tower Receiver Fixed Mirror Solar Concentrator
TANK TYPE COLLECTOR
The hot water storage tank is the heat absorber. The tank or tanks are
mounted in insulation box with glazing on one side and are painted black or
coated with a selective surface. The sun shine through the glazing and heats
the black tank, warning the water in side the tank .Usually tanks are made of
steel and the tubes made of copper.

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POOL COLLECTOR
This is a very active heating system applied in heating swimming pools.
They are unglazed and made of special copolymer plastics. These collectors
can not withstand the freezing conditions. Approximate maximum operating
temperature of this collector is 100
C – 200
C above ambience.
NOTE: Properties of Non-concentrating and concentrating collectors
Non-concentrating collectors Concentrating collectors
1. Absorb radiation received on
surface
 Converging solar radiation
from large area to small area
2. Both beam &diffused radiation  Beam radiation utilized
3. No optical concentration method  Optical methods( reflection,
refraction)
4. No need of solar tracking  Solar tracking required
5. Simple and compact construction  Diffused radiation cannot be
concentrated
6. Fixed on rigid platform-
maintanance free
 High temp attained
7. High temp cannot be achieved  Flexible construction

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5. PHOTO VOLTAIC CELLS (PV CELLS)
Meaning and general concept
A photovoltaic cell is a specialized semiconductor diode that converts visible light
into direct current (DC). Some PV cells can convert infrared (IR) or ultraviolent
(UV) radiation into DC electricity. Photovoltaic cells are an integral part of solar
electric energy system, which are becoming increasingly important as alternatives
source of utility power
The first PV cells were made of silicon combined or doped with other element to
be the behavior of electrons or holes (electrons absence of atoms) .Other materials
such as copper indium dieseline (CIS) cadmium telluride (CdTe) and gallium
arsenide (GaAs) have been developed for use of PV cells. There are two basic
semiconductor materials called positive or (P-type) and negative or (N-type).
In a PV cell, flat pieces of these materials are placed together, and the physical
boundary between them is called P-N junction. The device is constructed in such a
way that there the junction can be exposed to visible light, IR or UV.when such
radiation strikes the P-N junction, a voltage difference is produced between P-type
and N-type material. Electrode connected to the semiconductor layers allow
current to be drawn from visible.

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Components of solar system energy for system for lighting and other
domestics use
1. Panels: PV panels are the single biggest expense of a PV system. Their
placement and mounting affect your system performance more than any
other facet of the job.
2. Mounting equipment: Mounting your PV panels is of critical importance.
First, you need to mount the panels where they‟ll get maximum sunshine
over the course of a year. But the more difficult problem is to mount them
with enough integrity that they‟ll stay put for 25 years or more.
3. DC-to-AC inverters: Inverters take the low-voltage, high-current signals
from the PV panels and convert them into 120VAC (or 240 VAC), which is
directly compatible with grid power. From a reliability standpoint, they are
generally the weak link in any PV system, so quality is a must.
4. Tracking mounts: Tracking mounts mechanically move the PV panels over
the course of a day so that they directly face the sun at all times. Dual axis
trackers change both azimuth and elevation, while single axis trackers only
match the azimuth.
5. Disconnect switches: Disconnect switches are of critical importance, and
they need to be mounted within easy reach. Every member of your family
should know exactly how to turn the PV system off for safety reasons. If any
abnormal behavior occurs in your home‟s electrical system, shut off the
solar system first.
6. Wiring and fuse box connections: Wiring, conduit, and connections to
your household main fuse box are minor hardware expenses, but they
comprise a big chunk of the labor when you‟re installing a PV system.
7. Utility power meters: Conventional power meters are capable of spinning
backward, but utility companies usually change to a special digital meter
when you connect to the grid because most solar customers go to the
demands (time-of-use) rate structure, which requires more intelligent
Processing than a mechanical device is capable of recommended.

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RANTINGS OF DIFFERENT COMPONENTS BASED ON THE FARM
DEMANDS
1. MONO SOLAR PANEL(5W-360W)
Positive power tolerance 0 to 5W for each solar panel Good performance and
durable solar panel with 3.2mm thick tempered glass, for production of our
modules ww only use high quality mono crystalline sold cell.
APPLICATIONS
For charging 12V batteries, for example in vehicles and boats, boats, motorhome,
caravan, camping, narrow boat, yatch etc .

23
2. MONO CRYSTALLINE SOLAR PANEL
Features:
1. Excellent module efficiency up to 19.58%
2. Reducing power loss caused by covering ( dirty effect)
3. Excellent low- light
4. Heavy snow load up to 5400 pa
5. Salt mist, ammonia and blowing sand resistance, apply to seaside farm and
desert environment.
3. FLEXIBLE SOLAR PANEL(20W- 160W)
This solar panel series 20W to 160W mainly provide free power for charging 12V
batteries, semi- flexible solar panel are widely used in many agricultural fields.
This flexible solar panel light weight and thin contain no glass or aluminum, can be
easy installation on curved solid surfaces, with high efficiency up to 23.70%
APPLICATIONS
widely used in real estate, lawn vehicles, yatchs, light roofs, golf carts etc .
4. LIGHT SOLAR PANEL(50W-100W)
These light weight solar panels utilize an advanced material property to reduce the
reflection. This makes the solar panel module perfect for applications where glare
become a critical safety issues like military bases, airports and highways.

24
6. SOLAR ENERGY COMPONENTS SYSTEM
Repair and maintenance of solar energy system components.
Solar systems use a simple, manageable technology that home owners and
businesses can use to contribute to CO2 reduction. The fact that there is great
interest in solar energy can be seen in the steadily growing number of solar
installation companies. Their staff must have technical knowledge if the solar
power systems are to function reliably. Large energy parks are normally equipped
with a comprehensive monitoring system. In addition, these parks employ
specialists of operations management. The situation is different for the countless
small systems installed on the roofs of private houses and the medium-sized
commercial systems on the roofs of businesses and warehouses. Technical
amateurs are responsible for a number of these systems. Businesses at least have
electro-technical personnel on their facility management staff that can operate and
maintain their own systems. Concluding a maintenance contract is another
common practice. However, after start-up, there is usually no professional to look
after solar systems. But if the owner notices a drop in power generation and repairs
are therefore to be carried out, or if renovation is undertaken near the system, those
performing the work should be conscious of the fact that they are dealing with an
electrical system with high voltages and currents.
COMPONENTS OF SOLAR ENERGY SYSTEM
SOLAR PANELS – In most home DIY installations these panels will be built by
you from individual parts. You can order discount photovoltaic cells online, and
assemble these into complete 80W,100W, or 120W Solar Panels. But if you do not
have the time or skills to build a solar panel from scratch, there are plenty of
commercially available panels to choose from. Once built,individual panels are
wired together to make larger solar arrays.
SOLAR ARRAY DISCONNECT – This is basically just an electrical switch but
is an important part of the system. It allows you to disconnect and cut-off the DC
power output from your solar panels and array should any repairs be required or if
there is a problem with the solar system. This disconnect switch needs to be strong
enough to handle the full power output from the panels on a bright sunny day.

25
SOLAR PANEL BATTERIES- For storing energy, the type of battery needed for
a pv system is called a deep cycle battery. A deep cycle battery is quite different to
your average automobile battery, which is not durable enough for use in pv system.
Deep cycle batteries last five to ten years and recover around 80% of the energy
they take in. Batteries should be kept in a space that is ventilated away from living
areas and electronics but easily accessible for maintenance
BATTERY CHARGE CONTROLLER – Most home solar systems are built
with a battery backup included for when the sun does not shine such as on dull
days or at night. The battery charge controller ensures that a consistent amount of
electrical power is sent to the batteries so that they are not over charged, and to
ensure that the backup batteries do not discharge back through the system at night.
In many ways this component is similar to your automotive battery charger so will
not be too expensive.
SOLAR POWER CONVERTER – Your solar panels generate DC power, and
your home runs on mains AC power, the solar power converter converts the solar
energy from the panels into usable energy in the home by providing the DC to AC
conversion using electronic switching techniques. In practical terms, the converter
allows us to run electric drills, computers, vacuum cleaners, mains lighting, and
most other mains electrical appliances that can be plugged into the wall sockets of
your solar panels. There are many square wave, sine wave modified wave
converters on the market but a good quality 1200W converter likely won‟t cost you
more than $100(≈ 126,200Tsh).
BACKUP POWER – This for when the sun does not shine and the batteries are
empty. Most systems will include some sort of backup power. In a standalone
installation this would generally be a diesel generator. In a grid-tied system the
utility grid itself would provide the backup power through the converter. But a
backup power source can also be a wind turbine or a water wheel as part of a small
scale hydro system. So whether you build your own solar panels from scratch or
buy pre-made commercial panels, using solar energy to power your home can be
easier than you think. With a grid connected system you can even sell excess
electricity you do not use back to the utility company who have been selling it to
you for all these years giving you an additional income.

26
MAINTAINANCE
Panel Cleaning
It is important over the lifespan of an array to maintain optimal energy output. In
order to accomplish this, panel cleaning will be necessary. Cleaning early in the
morning when the mirrors are wet from dew is probably the best time to clean the
panels because dust can easily be rinsed without coating removal or damage. The
best technique today in the strategy of high-pressure sprays is a spray with
commercial anionic detergents. Effective cleaning solutions employ chemicals
which reduce surface tension, lower the cost, are capable of being handled and
mixed by automated equipment, and are non-toxic, safe, and biodegradable.
Detergent based solutions are normally able to restore the surface to 98% of its
original reflectance. High-pressure sprays proved to be a very effective method for
cleaning large scale arrays. A Benchmark of 3-gallon per minute spray (with
detergents) recovered up to 90% of reflectance. If you are hiring a professional
cleaning service to clean your panels, confirm that they are using the best methods,
and that you are getting what you paid
When to clean
Because it is variable how often one should clean, an algorithm should be used to
determine when cleaning should be done to be as cost effective as possible. This
means cleaning when the cost of energy lost exceeds that of cleaning. In order to
calculate this, first one must adjust the actual energy production. This means taking
the ratio of the actual solar irradiation your PV system receives to the expected
solar irradiation. Once the actual energy production has been calculated, one must
compare the result to the expected projection (adjusted for natural degradation).
When the cost of energy lost exceeds the cost of cleaning the panels should be
cleaned. This is a simple formula to follow, but requires an accurate monitoring
system to utilize. This is because every day of the year has a different projection
for energy production: The incidence angle changes and solar irradiation varies by
day. For short sample records, the result is small enough that it is negligible, but
comparing month to month produces better results. However, it is hard to do this
comparison without accurate month to month data, which means drawing on data

27
from an installation in operation for more than a year, or using a very accurate
prediction tool. In order to determine when to clean, the cost of cleaning has to be
acquired. This can be difficult because cleaning companies require a visual
inspection to get an accurate prediction on the cleaning cost.
Warranties
It is important to take advantage of warranties to reduce costs. At the time of
installation the buyer receives information regarding everything from operation
procedures, inverter information, module information, combiner information,
racking information, monitoring system, electrical balance of systems, as-
built/plans, and maintenance options. Amongst this information are the product
warranties for each aspect of the PV system. It is important to utilize this
information so that warranties can be enforced. Being able to prove that something
has failed under warranty is key to reducing the lifetime costs of an installation.
When trying to enforce a warranty, consult the installer of the array first, before the
manufacturer. It is often in the best interest of the installer to help you to maintain
their reputation. It is difficult to contact the manufacturer directly, and an attorney
may need to be involved in order to make sure manufacturers uphold their
warranties
SOLAR PANEL REPAIR
Our solar panel repair service includes the following
1. Replacement and testing of inverters
2. Replacement or repair of panel mounting hardware
3. Analysis and detection of inverter faults
4. Replace and testing of panels
5. Analysis and repair of electrical malfunction and ground faults
Summary
Inverters automatically react to the absence of the network and shut down. Why
should solar modules not do the same thing and thereby make the entire system
safe? Such switching apparatus would autonomously ensure a safe environment,
allow planned shut-downs for maintenance, and even facilitate initial system
installation because high voltages would only be activated when the system has
been completely assembled.

28
7. SOLAR ENERGY IN TANZANIA
The Tanzanian solar energy sector has been fast growing in recent years and
solar products are now a common sight in shops and markets throughout the
country. Several factors have contributed to this growth. On the supply side,
ever increasing work on research and development have greatly reduced the
prices of solar-PV products worldwide. The prominence of China in producing
solar panels at mass scale has reduced prices even further. On the demand side,
frequent power outages and a high cost for connection to the grid have made
Tanzanians consider alternatives to TANESCO (Tanzania Electric Supply
Company), like solar energy. With only 4% of rural households having access
to electricity, there seems to be specific potential for solar solutions in these
areas. Past awareness raising campaigns by government and NGOs (like
Sida/MEM and UNDP/GEF Mwanza) has helped raise knowledge and
understanding of solar products among consumers. The decision by the
Government of Tanzania to drop VAT and duties on all solar products has made
the solar market very interesting to entrepreneurs and many organizations and
commercial institutions dealing in solar products have started their activities in
recent years. Located in the „solar belt‟, most parts of Tanzania have abundant
solar resources throughout the whole year with the low point occurring in July.
The lowest annual average is 15 MJ or 4.2 kWh/m2
/day and the highest is 24
MJ or 6.7kWh/m2
/day. With such high levels of solar energy resources,
Tanzania is naturally suitable for application of solar energy as a viable
alternative source for modern energy services supply for rural electrification
and in general.
Different types of solar technologies exist, with different market dynamics and
technological solutions for each one of them:
1. Off-Grid Solar Lighting or Pico-Solar Products (1-10W): small, affordable
and easy to use - often hand held – products that provide basic lighting and
phone charging services to off-grid households
2. Solar Home Systems (SHS, 10-200W): a system that includes a solar panel,
battery and invertor that can provide a household with electricity for several
devices like light bulbs, TV and a small refrigerator. These systems can also
be used for institutions like schools and hospitals.
3. Mini-Grids for rural electrification: system with several large solar panels,
that provides electricity to a number of households in a rural community.
Solar for power generation: large solar systems set up to contribute
electricity to the national grid.

29
In recent years, many small scale solar lighting products have entered the
Tanzanian market. These off-grid lighting products or systems that are stand-alone,
rechargeable and can be installed, assembled and used easily without requiring
assistance from a technician have come to be known as „pico-solar‟ products. They
range from solar lanterns to small solar home systems (SMS), from 5 up to 100
euros in price and typically consist of a small solar panel, a rechargeable battery
and an LED bulb. Entry level pico-solar products can only be used for lighting, but
the more advanced systems also offer phone charging services. Because of the
affordability and ease of use of these products, they are very well suited for rural
off-grid households and can serve as an ideal replacement for kerosene lamps that
are currently being used for lighting in most Tanzanian rural households. The solar
lights can also give school children the chance to study in the evening.
Some general observations about the off-grid solar lighting sector in Tanzania.
There is high willingness to acquire solar lighting products among rural
Tanzanian household, especially when the device can also be used for phone
charging.
General awareness about the products varies between different parts of the
country, depending on awareness raising campaigns about solar PV that
have been undertaken previously.
VAT and duty exemptions are in place for all solar products in Tanzania,
making it a viable and attractive market for suppliers and retailers.
Main concern is the huge influx of poor quality or fake solar products to the
local markets throughout the country.
Distribution of fairly priced, high quality solar lighting products to off-grid
communities is lacking.
After sales services and warranty systems are often not in place or
impossible to access for off-grid households.
Energy utility by TANESCO does not see solar energy as a main priority for
electricity generation for the national net. In the latest Power System Master Plan
(2012) the following section is contributed to solar PV: ‘Contemporary solar PV
technology is done at small scale level. Application of solar power technology in
Tanzania at large scale is not well established. However, in this update solar
power was considered, with a potential to undertake pilot project before engaging
many players.’

30
STATUS OF APPLICATION OF SOLAR ENERGY IN TANZANIA
According to TANZANIA FACT SHEET under Federation of Universities of
applied science (FUAS) in the article “TANZANIA & RENEWABLE ENERGY
Country at-a-glance” described the Renewable Energy Policy .
The National Energy Policy (2003) focuses on market mechanisms and means to
reach the objective, and achieve an efficient energy sector with a balance between
national and commercial interests. The overall aim of the policy is to:
have affordable and reliable energy supplies in the whole country
reform the market for energy services to facilitate investment - Tanzania
approved feed-in Tariffs for renewables in 2009
enhance the development and utilization of indigenous and renewable
energy sources and technologies
adequately take into account environmental considerations for all energy
activities
increase energy efficiency and conservation in all sectors
increase energy education and build gender-balanced capacity in energy
planning, implementation and monitoring The 2009 Electricity Act opened
the Tanzanian electricity sector for private companies and ended 40 year
monopoly held by TANESCO in the national power sector. Independent
power producers (IPP) penetration so far has been limited, but is steadily
increasing. The Rural Energy Act of 2005 established the Rural Energy
Board, Fund and Agency responsible for promotion of improved access to
modern energy in rural areas.
Finally concluded that .The Potential for solar PV technology is GOOD with an
average daily solar insolation of 4.6 kW h/m².

31
8. GENERAL OVERVIEW DISCUSSION ON SOLAR ENERGY
Solar energy is a renewable energy, therefore have the following advantages
1. Once solar panels are installed, they produce energy without generating
waste or pollution. They operate with little maintenance or intervention.
2. Solar electric generation is economically competitive where grid connection
or fuel transport is difficult, costly or impossible. For example: satellites,
island communities, remote locations and ocean vessels.
3. Once the initial capital cost of building a solar power plant has been met,
operating costs are low when compared to other existing power
technologies.
The use of solar energy have also some limitations:
1. Solar energy systems do not work at night.
2. Solar cells are currently costly and require a large initial capital investment.
3. For larger applications, many photovoltaic cells are needed, corresponding
to high investment costs and large land Requirements.
4. The cost effectiveness of a solar energy system is dependent upon the
location and climate.

32
REFERENCES
Energypedia , Tanzania Energy situation, retrieved on 15th
may 2018.
https://energypedia.info/wiki/Tanzania_Energy_Situation#Solar_Energy
Lighting Africa, 2013. http://lightingafrica.org/where-we-work/tanzania/
SNV Tanzania (Netherlands Development Organisation), off-grid electricity.
retrieved on 15th
may 2018
http://www.snv.org/sector/energy/product/grid-electricity
TANESCO , Rular energy act 2005.
http://www.tanesco.co.tz/index.php/media1/downloads/acts/54-rural-energy-act-
2005
USEA , current status of energy sector in Tanzania. Preceeding cooference 25th
february – 2nd march 2013 https://www.usea.org/sites/default/files/event-
/Tanzania%20Power%20Sector.pdf

SOLAR ENERGY - FARM POWER REPORT AE 215

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SOLAR ENERGY - FARM POWER REPORT AE 215