Solar Energy

The Ultimate
Renewable Energy Resource
PRESENTED BY:-
Dr. Rajendra Singh Thakur 1

RENEWABLE ENERGY SOURCES
• The renewable energy resources, namely-
1. Solar
2. Hydro
3. Wind
4. Biomass
5. Ocean (including tidal and wave)
6. Geothermal

SOLAR ENERGY
• The sun is a source of enormous energy.
• It is a fusion reactor,
• Distance of about 150x106 km from the Earth,
• It’s probable age is 4x109 years and it is expected to radiate energy for
another 4 billion years.
• The energy from the sun in the form of radiations is called “SOLAR
ENERGY”.
• It is believed that with just 0.1% of the 75,000 trillion kWH of solar energy
that reaches the earth, the planet requirements can be fulfilled.

The energy received from the Sun in various forms is
called Solar Energy.

Solar energy technologies
• Solar energy technologies comprises of two categories-
1. Thermal conversion: take place through direct heating
• Ocean waves and currents
• Wind
2. Photo conversion:
• Photosynthesis,
• Photochemistry
• Photo electro chemistry
• Photo galvanism and
• Photo voltaic

Solar radiation is collected and converted by natural collectors such as-
• The atmosphere
• The ocean and
• Plant life
As well as by manmade collectors of many kinds.
• Sun
• Solar Radiation through
• Heat- Solar thermal heating & cooling, Process heat biomass
• Electricity - Photo voltaic, Solar thermal, OTEC, Wind mills
• Mechanical Energy - Windmills
• Chemical/Fuel- Biochemical conversion

•Contribution at present 69.9% needs are fulfilled by
coal, petroleum and natural gas.
•That is non renewable sources & limited.
• Sufficient petroleum fuels are not available today.
•Hydro energy is available 26%.
•Nuclear energy is 2.6% and
•Non conventional energy sources are 1.5%

Theoretical, technical potential and
current uses of renewable energy
RENEWABLE
ENERGY
SOURCES
CURRENT USE
(EJ)
TECHNICAL
POTENTIAL (EJ)
THEORETICAL,
POTENTIAL (EJ)
Hydro power 9 50 147
Biomass energy 50 276 2900
Wind energy 0.12 640 6000
Solar energy 0.1 1575 3900000
Ocean energy NA NA 7400
Total Energy 60 1800 4000000

(1) Solar Water Heating
(2) Solar Space Heating
(3) Air Conditioning
(4) Solar Refrigeration
(5) Solar Drying
(6) Solar Cooking
(7) Solar Greenhouse
(8) Solar Furnaces
(9) Solar Desalination
(10) Solar Production
(11) Solar Electricity- Thermal
(12) Solar Electricity- Photovoltaic

(1) Solar Water Heating
First, Endothermic process
• Solar radiation through the glass cover, is absorbed by collector plate and the wall along the finned tube
is passed to the heat absorption of water.
• As the water continues to move up and stored in the tank top, while constantly replenished through the
circulation pipe.
• Flat plate solar collector of the core performance of the main factors, one structural design, the second is
the surface absorption coating.
• Well-designed collector’s efficiency to be 93%. Collector fin efficiency and the board core structure,
surface treatment and the overall structure of the collector.
• The overall structure of the collector can be used to describe the overall heat transfer coefficient, and its
influence and its geometric dimensions (fin thickness, material) are the same.
Second, Circulation line
• Solar water heaters usually work the way the natural cycle, no external power, well-designed system, as
long as there is more than 5 ~ 6 ℃ temperature can cycle very well.
• In general, the hydraulic radius of the branch should be 10mm or more.
Third, The process of using top-water type
• Solar Water Heater way into water into water type and top-water type.
• Domestic solar water heater designed to the top of the water mode, the structure inside the water tank.
• Designed using the pipe can be converted into the best type of connection drowning in the water deficiency
or water stress during emergency use.

(2) Solar Space Heating
• Solar space heating of building can be provided passively through architectural design
of premise.
• Simplest, this involves only orientation of building and providing large south windows.
• More radical possibilities include provision of entire wall can be double-glass windows
or heavy dark –colored south facing wall.
• The system components in a space heating application are the same for water heating
with the addition of radiators for space heating or under floor heating coils or even
forced air systems.
• A radiator system will generally work in a very similar manor to the hot water
application,
• The main difference is the inclusion of a boiler, heated water from the collector is
passed through the heat exchanger or drain back tank and is then passed to a boiler
with is used to supplement the water hearing requirements before passing into the
radiators to be used for space heating.

(3) Air Conditioning
• Solar AC, providing a heating and cooling system that requires
no electricity to drive the air conditioning cycle.
• The parabolic trough thermal solar system provides the
required energy to operate the air conditioning unit.
• The air cooled chiller is itself a cleaner and more efficient
system than standard air conditioning units.
• This electricity is also provided from Solar Energy with a
small PV collector.

• The diagram above
shows sunlight striking
the parabolic solar
energy collector
located on the roof of
a home.
• The collector heats up
the transfer fluid,
which is held in a
special storage tank.
• This heat is then used
to power the
absorption cycle air
conditioning unit. Dr. Rajendra Singh Thakur 20

(4) Solar Refrigeration
• Energy supply to a refrigeration and air- conditioning system plays a significant role in
the world.
• Required food preservation or storage of medical and biological material.
• Demand of cooling is generally high when solar intensity is high.
• Solar energy can be converted to heat and electricity, and all heat, mechanical work
and electricity can drive cooling machines.
• Records show that the idea of solar refrigeration dates back more than 100 years, but it
was not until the energy crisis in the 1970s that close attention was paid to solar
refrigeration.
• The efficiency of the system depends on the solar energy conversion equipment and
the refrigeration subsystem.
• The technical consequences of the solar cooling technology from energy source to
service for both solar thermal-driven systems and photovoltaic-driven systems are
presented in the following picture.

(5) Solar Drying
• The solar dryer is a relatively simple concept. Solar energy used for Agriculture and Animal products
methods utilizing direct traditional and widespread.
• Agriculture products like-
 Drying of Copra,
 Drying of Grain,
 Drying of Hay,
 Drying of Fruits and
 Drying of Vegetables
 Drying of Herbal Products
 Drying of Other Agro Products
 Drying of Chemical Solid Waste
 Process Heating
• The basic principles employed in a solar dryer are:
• Converting light to heat: Any black on the inside of a solar dryer will improve the effectiveness of
turning light into heat.
• Trapping heat: Isolating the air inside the dryer from the air outside the dryer makes an important
difference.
• Moving the heat to the food. Both the natural convection dryer and the forced convection dryer
use the convection of the heated air to move the heat to the food.

• Simple combinative dryer consisting –
 Box insulated at Base,
 Painted black on inner side
 Covered with glass
 To facility flow of over drying material ventilation hole
at base and top side
 Drying material place on carefully design perforated
trays/racks inside combination.
 Adoption of improve process control has resulted
product quality.
 Large portion of world supply of dried fruits and
vegetables continue to prepared by sun drying.
 No doubt chipper and simplest to dry crops in regions
having abundant sunshine, low relative humidity, little
or low rainfall.
 Ex. Spray drying of Milk and fish drying of solar dried
animal products. Dr. Rajendra Singh Thakur 26

(6) Solar Cooking
• The box cooker is a simple type of solar cooker and a typical solar cooker is well insulated
shallow rectangular, square, metal box.
• At may be 3 to 5 feet (1 to 1.5 meters) across.
• At its most basic, the box cooker consists of an open-topped box that's black on the inside,
and a piece of glass or transparent plastic that sits on top.
• It often also has several reflectors (flat, metallic or mirrored surfaces) positioned outside
the box to collect and direct additional sunlight onto the glass.
• To cook, you leave this box in the sun with a pot of food inside, the pot sitting on top of the
black bottom of the box.
• When sunlight enters the box through the glass top, the light waves strike the bottom,
making it scorching hot.
• Dark colours are better at absorbing heat, that's why the inside is black.
• The molecules that make up the box get excited and generate more heat.
• The box traps the heat, and the oven gets hotter and hotter .
• The effect is the same as what goes on in a standard oven: The food cooks.
• Box cookers can reach up to 300 degrees F (150 °C).
• That's hot enough to safely cook meat.

Merits limitations
• Requires nighters fuel nor attention
• No pollution, no charging or
overflowing of food.
• Nutritional value very high, vitamins
and proteins.
• Maintenance cost negligible.
Can’ t use at night & cloudy days.
Taking more time.
Chapatti/roti can’t cock.

(7) Solar Greenhouse
• We are all familiar with the conventional greenhouse; a building or structure
with glass or plastic windows used to facilitate the growing of plants.
• Solar greenhouses differ from conventional greenhouses by their ability to
store solar energy for times when there is little or no sunlight.
• This is done in a variety of ways depending on the function of the greenhouse.
• Our interest is in ‘passive’ solar greenhouses and particularly, pit
greenhouses.
• These buildings harvest, store and deliver energy without the use of external
energy, hence their low cost.

The Basics of Passive Solar Design
– The plastic or glass glazing is the key to what is often called the “greenhouse effect.”
– The basic idea of the solar greenhouse is that the radiation heat generated by the plants is
absorbed by other objects in the greenhouse for storage.
– Solar radiation enters the greenhouse through the glazing in the form of light and is
absorbed by the plants and other surfaces.
– The light is then changed to thermal energy, or heat. The light is of course essential for
photosynthesis and plant growth but the real key to an effective solar greenhouse is
management of the heat.
– Properly designed greenhouses will store enough heat to sustain the plants through colder
temperatures. The task, then, is in keeping the heat in the greenhouse.
– This natural exchange of heat is the beauty of a passive system.

(8) Solar Furnaces
• Furnaces initially used wood or coal as conventional fuel.
• The need for the fuel is always increase.
• Because of that, people have to use the other naturally occurring resources, which are in surplus, like the solar energy.
• The basic principle of these devices is concentrating the sun rays onto the desired point to generate very high
temperatures.
• The concentration of sun rays is achieved by using convex lens. Then, the heat that generated can be converted to any
form of energy.
• Basically this system requires the mirror to have curvature to refract the rays to the desired point.
• A higher temperatures can be produced by positioning the mirror that will reflect the ray completely.
• With the number of mirrors and the angle of the position, the amount of heat generated can be controlled.
• For generating extremely high temp. (up to 3500°C) under very clean conditions to melt refractory materials.
• Solar furnaces high temp. obtained by concentrating solar radiation on to a specimen using no. heliostat's (turn able
mirror) arranged on sloping surface.
• Ex. The manufacturing of fused aluminum crucibles and studying the properties of ceramic of very high temp.
• It is anticipated that in future , solar furnace can be utilized in the production of Nitric acid and Fertilizers from air.

(9) Solar Desalination
• Solar energy for desalting and brackish well water demonstrated several moderate sized pilot plants
world including USA, USSR, Greece, Australia & other.
• Country old process of solar distillation, the basic type still has been modified and adapted to modern
materials.
• In this process, a solar collector is used to concentrate solar energy to heat the feedwater so that it can
be used in the high temperature end of a standard thermal desalination process.
• Solar radiation passes through the cover and is absorbed and converted into heat causing the water to
evaporate from the brine.
• The vapors produced get condensed to from purified water on the underside of the cooler glass cover,
flow down the sloping roof, collected in the troughs and from there into a water storage tank.
• The excess brine that has not evaporated is run to waste.
• These units tend to be very capital intensive and require specialized staff to operate them over a long
period of time.
• In addition, they require additional energy inputs to pump the water through the process.

(10) Salt production
• Solar evaporation of sea water (brine) is traditional method of obtained salt.
• Methods for salt production today on both small and large scale in development countries
include India, Pakistan, Chile, Mexico & Columbia.
• Basic concept is very simple in area where evaporation exceeds rainfall a shallow pool/pond
of brine evaporating water heaving behind salt.
• Latest concerned with improved pond/pool construction and salt harvesting technologies.

(11) Solar Electricity- Thermal

• Solar electricity may be used to heat a fluid, which then generates electricity through a conventional heat engine.
• To obtained an adequate working temperature, some from of concentration of solar energy is required.
• Broadly systems- fall in two category systems in which (1) Individual mirrors track the sun continuously and (2)
mirrors are fixed (or can be adjusted from day to day , but not track continuously).
• (1) Continuous tracking system - use a large number of plan or curved mirrors (Heliostats), each steered to reflect
sunlight on to a single tower mounted boiler.
• Parabolic trough power plants consist of numerous trough-shaped parabolic mirrors that concentrate sunlight onto
receivers (absorber tubes), along the focal line.
• Give high temperature & high efficiency but requires complex, rugged and accurate mechanism for the heliostats.
• (2) Most common forms of non-tracking system of assemblies of trough shaped collector (cylindrical and parabolic)
• Inside these specially coated receivers, concentrated solar radiation heats a special heat resistant transfer fluid to
temperatures of up to 400° Celsius (752 °F).
• This fluid is pumped to the central generating unit. It passes through several downstream heat exchangers and, as in
conventional power plants, generates the steam that is required to drive the turbines that produce electricity.
• Certain regular maintenance is needed on the mirrors, collectors and turbines.
• For instance, the receivers and mirrors need toD rb. eRa pjeenrdiorad Siicnaglhly T hwaaksuhr ed. 42

(12) Solar Electricity- Photovoltaic
A solar cell, or photovoltaic cell (PV), is a device that converts
light into electric current using the photoelectric effect.

How do Photovoltaic work?
• Invention in 1955, use for providing electric power by solar energy
to space croft.
• Photovoltaic effect produces a flow of electrons.
• In short, electrons are excited by particles of light and find the
attached electrical circuit the easiest path to travel from one side
of the cell to the other.
• This warming is caused by the exciting of electrons, bouncing back
and forth creating friction and therefore heat.
• This flow of electrons is, by definition, electricity.

• An electrical current is the flow of electric charge from one point to another.
• Solar cells are made of semiconductor materials - crystal silicon.
• Current can be carried either by the flow of electrons or by the flow of positively-charged
"holes”.
• Pure crystal silicon is almost neutrally charged, so it would not function well to produce
electricity. So other elements must be added to achieve a negative or positive charge, this
process is called doping.
• So there are two types of silicon that work together in transferring sunlight into power.
The first is N Type (negative) silicon, which has been added with phosphorus and has much
more electrons for photons to "break loose".
The second is P Type (positive) silicon, which contains boron thus having free openings,
or holes.
The junction area has a thin slice of P-type silicon (wafer) that has been diffused with a N-type
dopant (phosphorus), or the other way around.
• At last, in terms of the electric process, the cell needs to be connected to an external load.
• Thus negative charges travel to a wire, power the load and continue until reaching a p-type
metal contact where it combines with a positive charges.

• Solar panels are comprised of several
individual solar cells which are
themselves composed of layers of
silicon, phosphorous (which
provides the negative charge), and
boron (which provides the positive
charge).
• This entire process is known as the
Photovoltaic Effect.

MERITS
• Requirement of electricity for decentralized applications.
• Easy installation & maintenance.
• Absence of noise & other forms of pollutions.
• Long life of SPV, favorable remote & isolated, forest &
desert area.
LIMITATION
• High initial cost
• Expensive inputs silicon wafer.

Indian Scenario
• Solar energy centre under Ministry of Non-Conventional Energy Sources, under activities-
 Solar heating research,
 System design and engineering,
 Solar thermal power generation,
 Solar passive architecture and
 green house technology.
• Facility –
 Solar thermal and SPV(Solar Photovoltaic) device.
 It has Asia's largest indoor sun simulator for the measurement on solar thermal collectors.
• India’s installed capacity of-
 10,000 domestic and 5,000 industrial solar water heating systems.
 2.25 lakhs solar cooker
 10,000 solar stills
 200 solar huts

• The Government of India had launched the Jawaharlal Nehru National Solar
Mission as one of the National Missions under India's National Action Plan on
Climate Change.
• It has the twin objectives of contributing to India's long-term energy security and
its ecologically sustainable growth.
• The immediate aim of the Mission is to focus on setting up an enabling environment
for solar technology penetration in the country both at centralized and
decentralized levels.
• The Solar Mission envisages the implementation of the Mission in 3 stages leading
up to an installed capacity of 20,000 MW by end of March 2022. The objectives
and the targets for the Mission are-
 To create an enabling policy framework for the deployment of 20,000 MW of solar
power by 2022
 To ramp up capacity of grid-connected soar power generation to 1000 MW within
three years – by 2013
 An additional 3000 MW by 2017 through the mandatory use of the renewable
purchase obligation by utilities
 This capacity can be more than doubled – reaching 10,000 MW installed power
by 2017 or more
 To create favourable conditions foDrr. Rsaojenladrra Smingah nThuakfuar cturing capability. 55

SOLAR POND
• Solar ponds are also utilized to capture the sun's power.
• The principles of energy transfer by convection to heat water to steam for heat production.
• The bottom of the pond is dark colored in order to absorb the sun's rays.
• The pond is filled with saline water made with NaCl, MgCl2, sodium carbonate, or sodium sulfate.
• A gradient is maintained at varying densities.
• The bottom is the most dense and is used as a storage zone. It is convective and can store a working
temperature of up to 80-85o C.
• Above the bottom layer is a non-convective zone, or insulation zone, with a density gradient which
facilitates a temperature gradient as well. This layer functions as insulation.
• The top layer, or surface zone, is convective due to wind-induced mixing and daily heating and cooling.
These layers are represented in the hot brine, or salt water, on the bottom may be extracted and used
for direct heating and low-temperature industrial uses like drying crops and agricultural shelter heating.

Merits
• Low cost /unit area collectors built large storage capacity.
• Constructed over large area enabling diffused solar
radiation.
• Can supply energy during monsoon session.
• Utilize various purpose.
LIMITATION
• Multipurpose facilities involves-
• Higher capital cost,
• Development of process and potential applications.
• Less attractive in development countries.

Indian scenario
• First Asian country to have solar pond project in
Bhuj, Kutch Disst. Of Gujrat design to supply-
 About 220 lakh kWh of thermal energy/Anum.
 About 1,25,000 kWh of electricity/Anum.
 About 80,000 liter of potable water/Day.

• The international organization for standardization has
established a number of standards relating to solar
energy equipment.
• For example, ISO 9050 relates to glass in building
while ISO 10217 relates to the materials used in solar
water heaters.

(1) The most, environmentally friendly source of energy that can be used on earth.
(2) It can be used to produce electricity or heat without a by product .
(3) It poses no danger of radioactive contamination to anyone as there is no
breaking down of any radioactive material.
(4) It can generate electricity or usable heat without noise.
(5) The source of solar energy is inexhaustible as long as the sun is there.
(6) It is free and can be used by anyone in abundance.

(1) Solar energy technologies still remain a costly alternative source.
(2) A solar energy installation requires a large area
(3) Solar energy is only useful when the sun is shining.
(4) The location of solar panels can affect performance, due to
possible obstructions from the surrounding buildings or landscape.

(1) According to some experts, the sun is our best source of renewable,
clean energy.
(2) Some estimate that the sun can produce 10,000 times as much
energy as the earth uses.
(3) The future of solar energy depends mostly on how it is applied.
(4) The largest problem facing the future of solar energy is the space
required to build solar power plants.
(5) One encouraging factor about the future of solar energy is that
many of the world's greatest innovators are choosing to focus their
considerable talent and funds on improving alternative energy
technology.

Thank you for your attention!

Solar Energy

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