Solar Energy

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Introduction to Solar Energy
What is solar energy?
The Source of Solar Energy
To get technical, solar energy is the radiant energy that the sun produces. This is
the result of a process called nuclear fusion - the joining of smaller atoms to
form a larger atom.
The sun is a giant ball of gas consisting primarily of hydrogen and helium.
Through nuclear fusion, hydrogen atoms in the sun's core combine to form
helium atoms over and over again.
The Law of Conservation of Energy
Each time this nuclear fusion reaction takes place, the nuclei of four hydrogen
atoms fuse to become one helium atom. However, the resulting helium atom has
less mass than the four hydrogen atoms that fused with each other.
Does this mean that some matter is "lost" during the nuclear fusion process?
No, it isn't really lost.
Due to the law of conservation of energy, this "lost matter" is converted into the
radiant energy that the sun emits into space.
You now have the answer to the question, "What is solar energy?" Let's take it a
step further and see how solar energy travels to earth.
The Electromagnetic Spectrum
Once the sun emits this radiant energy into space, it makes its way to earth as
electromagnetic waves traveling at the speed of light. We perceive this solar
radiation as light, but in fact it spreads over a wider band of wavelengths known
as the electromagnetic spectrum. The electromagnetic spectrum organizes
electromagnetic energy by wavelength.

Supervisor: Prof.DR.Oasama Ezzat

The Electromagnetic Spectrum
One misconception about the solar energy that reaches earth is that it includes
the heat from the sun. In fact, the earth doesn't receive any heat from the sun
since it's more than 93 million miles away! What actually happens is that when
the radiant energy from the sun is absorbed by an object, its energy is converted
into heat.
Solar Energy: The Ultimate Renewable Energy
The sun produces a tremendous amount of energy. Every second, more than 4
million metric tons of hydrogen is converted into helium. But even at this rate,
the sun will continue producing solar energy for another 5 billion years! As a
result, solar energy is considered the ultimate renewable energy.

Why Solar Energy?
Global Energy Demand
Global energy demand is set to increase dramatically during the 21st century. As
more people in India, China, and other developing nations move from a lowimpact village life to a middle-class life, their energy demand will increase
The American lifestyle people are striving for includes bigger homes, more
electronic gadgets, more vehicles, and just more stuff that uses energy. All of
this results in energy consumption that can be up to 30 times greater than the
average person in China or India currently uses.
More than 200 million people made this move over the past 30 years, and
there's 200 million more on their way. As you can imagine, the demand for
energy is growing at a blistering pace!

Supervisor: Prof.DR.Oasama Ezzat

Sources of Energy
Today we get most of our energy from fossil fuels such as oil, coal, and gas. But
there are a couple of issues with this.
The first issue is the environmental damage caused by burning fossil fuels.
When fossil fuels are used to generate electricity they release greenhouse gases
into the atmosphere. This contributes to global warming.
The second issue is that all of the easy-to-find and easy-to-extract fossil fuels
have already been found. This means that as time goes on, it will continue to get
more expensive to find and extract fossil fuels. This in turn will lead to higher
prices for the end consumer.
Taking both of these issues with fossil fuels into account, you can see that
alternative energy sources will need to come into play in a significant way in
order to meet the global energy demand. These alternative energy sources
include renewable energy such as solar energy, wind, biomass, hydro-electric,
and geothermal.
But why use solar energy?
Of all the renewable energy sources, solar energy holds the most promise for
providing a sustainable energy source. The German Advisory Council on Global
Change is forecasting that by 2100 solar power will be the largest source of
global energy.
The Solar Resource
There are several reasons why solar energy is the most promising alternative
energy resource for our future.
Scientists estimate that our Sun will continue producing solar energy for another
5 billion years! Talk about a sustainable energy source! We definitely do not
have to worry about running out of solar energy. It is the ultimate renewable
energy available to us.
In one hour enough sunlight reaches the Earth to supply its energy needs for an
entire year. So not only is it sustainable, but it provides more than enough
energy for our needs. We just need to continue improving our solar technology
so that we can capture more of this energy and put it to productive use.

Supervisor: Prof.DR.Oasama Ezzat

But even with today's technology solar energy makes sense. A 100-square mile
solar energy field in the Southwestern United States could provide enough
energy to meet the entire U.S. energy demand. And for a homeowner who takes
advantage of solar electricity, solar heating, solar cooling, and solar lighting,
their home will use less energy than it produces.
What it Means for Homeowners
As the demand for energy increases, solar energy will come to play a dominant
role in global energy production.
Homeowners will benefit from this in two ways...
First, as more utilities, businesses, and even homeowner use solar technology, it
will become less expensive. This will make solar energy a great choice for
homeowners to use for their homes. Additionally, this will also drive more R&D
into solar energy resulting in even more efficient technology.
Second, as more utilities build solar power plants, there's a good chance the
energy you receive from your utility will be clean, renewable solar energy.
Before you know it, all homes will be net energy producers! And that energy
will be clean, sustainable, and renewable.

What are the different types of solar energy?
According to the way of converting:
Passive Solar Energy
Active Solar Energy
According to the type of the converted energy:
Solar Thermal Energy
Photovoltaic Solar Power
Concentrating Solar Power

Supervisor: Prof.DR.Oasama Ezzat

Passive Solar Energy
Passive solar energy refers to the harnessing of the sun's energy without the use
of mechanical devices. Using south-facing windows to provide natural lighting
and heat for your home are examples of passive solar energy.
There are several solar applications a homeowner can use to take advantage of
passive solar energy...
 Passive solar heating
 Passive cooling
 Day lighting
Active Solar Energy
Active solar energy uses mechanical devices in the collection, storage, and
distribution of solar energy for your home. For example, in active solar energy
water heating systems, pumps are used to circulate water through the system.
There are several solar applications a homeowner can use to take advantage of
active solar energy...
 Active solar space heating
 Active solar water heating
 Active solar pool heating
Solar Thermal Energy
Solar thermal energy is the energy created by converting solar energy into heat.
There are several solar applications a homeowner can use to take advantage of
solar thermal energy...
 Solar space heating
 Solar water heating
 Solar pool heating
 Solar thermal cooling
Photovoltaic Solar Power
Photovoltaic solar power is the energy created by converting solar energy into
electricity using photovoltaic solar cells.

Supervisor: Prof.DR.Oasama Ezzat

There are several solar applications a homeowner can use to take advantage of
photovoltaic solar power...
 Solar electricity
 Photovoltaic cooling
 Photovoltaic solar lighting
Concentrating Solar Power (CSP)
Concentrating solar power is a type of solar thermal energy that is used to
generate solar power electricity.
This technology is aimed at large-scale energy production. Because of this, as a
homeowner, you won't use concentrated solar power directly, but could take
advantage of it through a green-pricing service offered by your regulated utility
or an alternative energy supplier.

Supervisor: Prof.DR.Oasama Ezzat

Solar Energy uses
 Solar Electricity
 Solar Heating
 Solar Cooling
 Solar Lighting

1-Solar Electricity
Home solar power systems can help you...
1. Save money by reducing or eliminating
your monthly electrical bill
2. Become less dependent on your utility
3. Make a positive impact on the earth
For homeowners, this can all be accomplished by
installing a photovoltaic solar power system.
Solar Electricity Topics...

What is a PV Solar Power System?
PV Devices
Balance of System (BOS)
Types of PV Systems

What is a PV Solar Power System?
A PV system converts solar energy into solar electricity for use by electrical
devices in your home. It is made up of three subsystems.
1. PV Devices
2. Load
3. Balance of System (BOS)

Supervisor: Prof.DR.Oasama Ezzat

PV Solar Power System Diagram
The PV Devices generate the solar power by converting sunlight into directcurrent (DC) electricity.
The Load is simply the device that uses the electricity. Your refrigerator is a
good example of a load.
The BOS consists of all the equipment between the PV devices and the load.
It includes the structures for mounting the PV devices, the power
conditioning equipment to convert the DC electricity to alternating-current
(AC) for use by the load, and batteries for storing the PV generated
electricity if desired.
PV Devices
The solar cell is the basic building block of a PV system. It converts solar
energy directly into electricity through a process known as the photovoltaic
An individual solar cell doesn't generate much power. The amount varies,
but it is around 1 or 2 watts. But you can increase the solar power generated
by joining them together into a larger unit called a PV module. PV modules
are also known as solar power panels. The power output of a PV module
ranges from 10 watts to 300 watts. To generate even more power, PV
modules can be combined to form a PV array.

PV Cell, Module, and Array
Photo: Courtesy U.S. DOE/EERE
Supervisor: Prof.DR.Oasama Ezzat

A PV array can consist of any number of modules. This modularity makes
photovoltaic systems very flexible. They are able to meet any electrical
requirement, whether the amount of power needed is small or large.
But to take advantage of the electricity produced by a PV array, you need a
few more components...
Balance of System (BOS)
The BOS components enable the solar electricity to be properly applied to
the load.
1. Mounting Structures: The mounting systems needed to integrate your
PV array with your home's structural systems.
2. Array DC Disconnect: Stops the flow of electricity from the PV array.
Essential for system maintenance and troubleshooting.
3. Charge Controller: Monitors the battery bank to prevent it from being
4. Battery Bank: A group of batteries wired together that store the energy
produced by the PV array for later use.
5. System Meter: Allows you to monitor the performance and status of
your PV system.
6. Main DC Disconnect: Stops the flow of electricity from the battery
bank to the inverter.
7. Solar Power Inverter: PV arrays produce direct current (DC) power.
The inverter converts the DC power into the standard alternating
current (AC) power used in your home.
8. AC Breaker Panel: This is the same breaker panel you already have in
your house. This is where the power from your PV array and the
utility are routed to your home's electrical system.
9. Electric Meter: Measures the amount of electricity supplied to or
produced by your home. The utility uses it to calculate your monthly
electricity bill.
10.Backup Generator: Produces AC power that is converted to DC power
by the inverter for storage in the battery bank. Used when the PV
devices aren't able to produce electricity for prolonged periods of time.

Supervisor: Prof.DR.Oasama Ezzat

The exact BOS components you need will depend on the type of PV system you
Types of PV Systems
The three most common types of photovoltaic systems for residential solar
power are...
1. Grid-Tied PV System
2. Grid-Tied PV System with Battery Backup
3. Stand-Alone PV System

Grid Tied PV System
A grid-tied PV system allows you to use the electricity generated by your PV
system as well as electricity from the grid. When your PV system is
producing electricity, your home will be powered by solar electricity. During
the times when your PV system isn't producing electricity, such as at night,
your home will receive power from the grid.
Any excess electricity produced by your system can be fed back to the grid.
This is known as net-metering. With net-metering, when you use electricity
from the grid your meter spins forward and when you are providing
electricity to the grid your meter spins backwards. This offset means you are
actually receiving market rates for the electricity you provide to the grid!

Grid Tied PV System Diagram
For most people, a grid-tied PV system is the ideal configuration.
You get all the benefits of using your own solar electricity as well as the
benefits of being connected to the grid. It is also less expensive than other
types of PV systems.

Supervisor: Prof.DR.Oasama Ezzat

Grid Tied PV System with Battery Backup
A grid-tied PV system can also be supplemented with a battery backup.
Why would you need a battery backup since you are connected to the grid?
Well, grid-tied PV system inverters are designed to shut down when the grid
experiences a power outage in order to protect the utility repair workers from
being shocked by electricity coming from your PV array. As a result, during
a power outage, you won't be able to utilize the electricity coming from your
PV array.
However, if your PV system includes a battery bank, during a power outage
you can utilize the energy that your PV system produced and stored in the

Grid Tied PV System With Battery Backup Diagram
A grid-tied PV system with battery backup is ideal if you live in an area that
has unreliable power from the grid or that experiences power outages due to
natural disasters.
Stand Alone PV System
Stand-alone PV systems are designed to operate independently from the grid
and to provide all of the electricity you need for your home.

Supervisor: Prof.DR.Oasama Ezzat

Stand Alone PV System Diagram
If you have a home that is in a remote area that doesn't have utility grid
service or where it would be very costly to have power lines run to your
home, a stand-alone PV system would be ideal.
This type of PV system is also desirable if you are looking to go completely
green with your source of electricity.
Solar Electricity Your Way!
As you can see, home solar power systems give you a flexible way to
harness the power of the sun to generate your own pollution-free, cost-saving
solar electricity!

2-Solar Heating
Residential solar heating
systems can be used to heat your
home's living spaces, household
water, or swimming pool.
There are several applications
available to homeowners for
heating with solar energy.
Whether you are interested in
active or passive solar energy
systems, there are solutions to
suit your needs.

Supervisor: Prof.DR.Oasama Ezzat

But before we go through the different solar power heating applications, let's
take a look at the basic components all these heating systems have...
Components of a Solar Heating System
All solar thermal systems have three basic system components or functions...
Collection: A method to capture the solar energy coming from the Sun and
convert it to heat. Passive solar homes use the house design and structure to
collect solar energy. Active systems will use boxes called solar collectors to
capture the solar energy.
Storage: A method to store the heat that has been collected. Solar thermal energy
can be stored using thermal mass, water tanks, or rock bins that hold heated air.
Distribution: A method to distribute the heat throughout your home. This can be
done using either mechanical means (fans, pumps) or basic physical principles
(convection, conduction, and radiation).
Now that you know what the basic components of a solar thermal energy system
are, let's take a look at the actual applications you can use for heating with solar
Solar Heating Applications
There are three types of solar power heating applications you can use for your
Solar Space Heating uses solar thermal energy to heat the space inside a

Solar Water Heating uses solar thermal energy to heat your household water.
Solar Pool Heating uses solar thermal energy to heat your swimming pool
These three basic heating applications can also be broken down into active solar
energy systems and passive solar energy systems.
Active systems use mechanical devices such as fans and pumps for the
collection, storage, and distribution of the solar energy.

Supervisor: Prof.DR.Oasama Ezzat

Passive systems don't use mechanical devices. Instead they use design elements
and basic physical principles such as convection, conduction, and radiation for
the collection, storage, and distribution of the solar energy.
Benefits Of Heating With Solar Power
Heating with solar energy has economic, environmental, and energy
independence benefits for homeowners...
Economic: The economics of solar power will save you money! A Florida Solar
Energy Center study found that homeowners using solar water heating saved
50% to 85% on their annual utility bills compared to those using electric water
Environmental: Solar thermal energy applications do not pollute! By heating
your home with solar energy, you will reduce your carbon footprint and be
helping in the battle against global warming.
Energy Independence: By heating with solar power, you will protect yourself
from future utility price increases thereby gaining your independence from the
utility company! You will also help your nation reduce it's dependence on
foreign oil.
As a homeowner, solar power heating provides a number of simple and cost
effective ways for you to take advantage of solar energy.
Whether heating your home, your household water, or your pool, there's a solar
heating application that's just right for you!

3-Solar Cooling
There are three basic approaches
to solar cooling that you can apply
to your home.
The first is passive cooling, which
uses passive solar design techniques
to minimize the impact the summer
sun has on your home.
The next two approaches, solar
thermal cooling and photovoltaic
cooling, convert solar energy into
heat or electricity for use in a
cooling appliance. These two

Supervisor: Prof.DR.Oasama Ezzat

approaches take advantage of the high solar intensity on hot days, which is
when cooling is most needed, to provide the energy needed to power the cooling
Passive Cooling
Passive cooling uses passive solar design principles to reduce or eliminate your
home's need for mechanical cooling systems. By incorporating passive solar
design principles into your home's design and landscaping, your home will be
naturally comfortable and you will have lower energy bills.
These principles include...
1. Orienting your home to minimize the amount of sunlight that hits it
during the hot summer and to take advantage of the prevailing breezes.
2. Using landscape and structural elements for shading.
3. Creating pathways throughout the home for natural ventilation.
4. Insulating your home to maintain a comfortable temperature.
Solar Thermal Cooling
Solar thermal cooling is primarily used in commercial settings, but it is
becoming more common in residential applications. There are two applications
suitable for residential settings where solar thermal energy is used to drive the
cooling process.
Solar Absorption Cooling uses solar-heated water to drive an air conditioner.
The air conditioner uses a liquid that consists of an absorbent and a refrigerant.
Solar heat is used to separate the absorbent and the refrigerant from each other.
The refrigerant is then compressed and evaporated to create a cooling effect for
your home. The evaporated refrigerant is then recombined with the absorbent to
go through the process again.
Solar Desiccant Cooling doesn't really cool the air; it removes moisture from
the air which decreases the relative humidity. The moisture is removed by
passing the air through a material called a desiccant. As the desiccant absorbs
the moisture from the air, it becomes saturated and loses its ability to continue
absorbing moisture. At this point, the desiccant is then regenerated, or dried,
with solar heat which evaporates the moisture into the outside air. It is then
ready to absorb more moisture from the air entering your home.

Supervisor: Prof.DR.Oasama Ezzat

Photovoltaic Cooling
Photovoltaic cooling uses PV panels to generate solar electricity to power an
electrical cooling device. A PV system uses an inverter to convert the DC-power
generated by the PV panels into AC-power. The AC-power provides the
electricity to power a conventional air conditioner. There are even some air
conditioners that can be powered directly with DC-power. In those cases there
isn't a need for an inverter!
Photovoltaic cooling can also be used to cool your attic. Using a photovoltaic
solar attic fan or solar roof vents, you can improve the ventilation in your attic by
increasing the air circulation through the area. By cooling your attic you will
reduce your home's overall cooling expenses.

Solar Cooling Makes Sense
During the summer when the sun's intensity is the strongest, it makes sense to
harness that power and use it for cooling.
Whether using passive solar cooling to reduce the sun's impact on your home,
solar thermal energy for solar absorption cooling or desiccant cooling, or PV
panels to power conventional air conditioners, using a solar cooling system to
keep your home cool during the hot summer months makes a lot of sense.

4-Solar Lighting
There are two primary applications of solar lighting that you can use for your
1. Outdoor Solar Lighting
2. Day lighting
Outdoor Solar Lighting
Outdoor solar lighting uses photovoltaic solar power
technology to convert solar energy into solar electricity.

This energy is collected and stored during the day and
is used to power the light during the night.

Solar lights have many uses...
Supervisor: Prof.DR.Oasama Ezzat


Garden lighting
Pathway lighting
Driveway lighting
Patio lighting
Architectural lighting

6. Mission Solar Lights
7. Solar powered Christmas lights

A solar yard light
Solar lights provide a flexible alternative for outdoor designs. They are easily
placed and moved without the need for trenching or running electrical power
from your home. They also come in a wide variety of designs that can enhance
any landscape.
Another application of solar lighting is day lighting...
Day lighting
Day lighting is a passive solar energy application that uses natural light from the
sun to illuminate your home.
Using passive solar design principles to properly position and size your
windows as well as to provide appropriate shading, you can effectively light
your home naturally. For rooms that don't have windows, a solar tube can be
used to bring in natural light.
Day lighting enhances your living quality by bringing indirect natural light into
your home, providing a pleasing connection to the outdoors. This reduces your
electricity use and costs but does require careful planning to manage heat gain
and loss, control glare, and to account for the available sunlight during the day.
Lighting Your Home With Solar Energy
Solar lighting provides you with both active solar energy and passive solar energy
approaches that you can use for your home.
A solar light using photovoltaic solar power technology for power can be used
individually or in sets to enhance your homes outdoor living spaces. At the same
time, day lighting can be used to provide natural interior lighting that brings a
pleasant feeling to your home.

Supervisor: Prof.DR.Oasama Ezzat

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