3 chapter 3 solar energy

Chapter 3 Solar Energy
• Solar radiation
• Solar thermal energy
• Photovoltaics (Solar cells)
• CO2 capture and solar fuels
By : Prof. Ghada Amer

Chapter 3 Solar
Energy
• Solar radiation

Solar radiation
• Solar radiation is radiant energy emitted by the sun, particularly
electromagnetic energy.
• About half of the radiation is in the visible short-wave part of the
electromagnetic spectrum. The other half is mostly in the near-
infrared part, with some in the ultraviolet part of the spectrum.
• The sun is the source of all life on the Earth. The sun is an intensely hot,
self-luminous body of gases (mainly hydrogen and helium) at the center
of the solar system.
By Prof. Ghada Amer3/26/2018 3

Chapter 3 Solar Energy
• Solar radiation

Introduction
• We have always used the energy of the sun as far back as humans have existed
on this planet.
• We know today that the sun is simply our nearest star and without it, life would
not exist on our planet. We use the sun’s energy everyday in many different
ways.
• we hang our clothes out in the sun to dry, for drying fish, fruits, etc.
• Decaying plants hundreds of millions of years ago produced the coal, oil and
natural gas that we use today. So, fossil fuels is actually sunlight stored millions
and millions of years ago.
• Indirectly, the sun and other stars are responsible for ALL our energy. Even
nuclear energy in the fury of a nova – a star exploding.
• There are many applications for the direct use of solar thermal energy,
space heating and cooling, water heating, crop drying and solar cooking.
• The most common use for solar thermal technology is for domestic
water heating.

Solar Thermal Energy
• Solar Thermal Energy is a form of energy and a technology for
harnessing solar energy to generate thermal energy or electrical
energy for use in industry, and in the residential and commercial
sectors. And it have the following advantages
✓ Consumes no fuel.
✓ No pollution.
✓ No greenhouse gases.
✓ No moving parts, little or no
maintenance.
✓ Sunlight is plentiful &
inexhaustible.
✓ Considerably cheaper than
electricity from coal if cost of
carbon capture is factored in.
✓ Great promise for solving global
warming and fossil fuel
depletion problems. By Prof. Ghada Amer3/26/2018 6

Using Solar Energy to Provide
High-Temperature Heat and
Electricity
• Solar thermal systems
• Photovoltaic (PV) cells

How does solar thermal work?
• Have you ever felt warm water trickle out of a garden hose that’s
been sitting in the sun? If so, then you’ve witnessed solar water
heating in action.
• There are a number of different solar thermal designs, but all are
based on the same principle as the garden hose.
• Each has its pros and cons and each is suitable for a specific
application.

Different types of systems
• Passive and active
• The terms passive and active in solar thermal systems refer to
whether the systems rely on pumps or only thermodynamics to
circulate water through the systems.
Passive solar heating Active solar heating

 Produces electricity
 Can use batteries or
electric grid
 Can sell excess power
through electric grid
 Rapidly evolving
technology
 Heats water &
living spaces
 Has been used
throughout time
 More economical
than PV
Solar Thermal & Solar PV

Passive

Solar Collector
• Solar Thermal is a clean, highly efficient means of using
renewable energy from the sun to provide hot water for
domestic, commercial and industrial process .
• Put in simple terms, if you place a container full of liquid in the
garden on a sunny day, in a short time the contents of the
container become warm. Solar Collectors work in much the same
way, but are very more efficient.
• A sealed circuit of fluid containing a special mix of glycol and
water is pumped around the system through the Solar panels
where it is heated and passed through a special solar coil within
the hot water tank.
• The heat is then transferred to the main body of water within
the tank, once up to temperature, this water is ready for use in
the house, office or factory.

Types of Passive systems
• Passive Solar is accommodated in the design of some homes
where living rooms are south facing with large windows and
floors and sometimes walls have a large thermal mass.
• While it is necessary to use the solar to heat in winter
overheating in summer has to be avoided, this is normally
done by having a roof overhang which blocks the high summer
sun but not the low winter sun.
• While it can provide some free heat it doesn’t supply hot water
and there are design constraints.
• Conservatory or ‘sunspace’. A conservatory or greenhouse can
be thought of as a kind of habitable solar collector.
• Air is the heat transfer fluid, carrying energy into the building
behind.
• The energy store is the building itself, especially the wall at the
back of the conservatory.

Types of Solar Water Heating Systems
• Flat-plate collector
– Glazed flat-plate collectors are insulated, weatherproofed boxes
that contain a dark absorber plate under one or more glass or
plastic covers.
– Unglazed flat-plate collectors; typically used for solar pool heating,
have a dark absorber plate, made of metal or plastic, without a
cover or enclosure.

• Integral collector-storage systems
– Also known as ICS or batch systems, they feature one or more black
tanks or tubes in an insulated, glazed box.
– Cold water first passes through the solar collector, which preheats
the water.
– The water then continues on to the conventional backup water
heater, providing a reliable source of hot water.

• Evacuated-tube solar collectors
– They feature parallel rows of transparent glass tubes.
– Each tube contains a glass outer tube and metal absorber tube
attached to a fin.
– The fin's coating absorbs solar energy but inhibits radiative heat
loss.
– These collectors are used more frequently for U.S. commercial
applications.

Space heating
Certain guidelines that should be followed:
• A building should have large areas of glazing facing the sun to
maximize solar gain.
• Features should be included to regulate heat intake to prevent
overheating.
• A building should be of sufficient mass to allow heat storage for the
required period.
• Contain features which promote the even distribution of heat
throughout the building.

Trombe wall
• A massive black painted wall that has a double glazed skin to
prevent captured heat from escaping.
• The wall is vented to allow the warm air to enter the room at high
level and cool air to enter the cavity between the wall and the
glazing.
• Heat stored during the day is radiated into the room during the
night.

Active solar heating systems
• Active solar heating systems use solar energy to heat a fluid --
either liquid or air -- and then transfer the solar heat directly to the
interior space or to a storage system for later use.
• Active solar energy systems use the same principles as passive
systems except that they use a fluid (such as water) to absorb the
heat.
• A solar collector positioned on the roofs of buildings heats the fluid
and then pumps it through a system of pipes to heat the whole
building.
• If the solar system cannot provide adequate space heating, an
auxiliary or back-up system provides the additional heat.
• Liquid systems are more often used when storage is included, and
are well suited for radiant heating, boilers with hot water radiators,
and even absorption heat pumps and coolers. Both liquid and air
systems can supplement forced air systems.By Prof. Ghada Amer3/26/2018 21

Active

Solar thermal power stations
• Two types:
Power tower
Sources: Energy Information Administration, Electric Power Annual, Form EIA-860, Annual Electric Generator Report database,
2004.

Solar cooking
• This technology has been given a lot of attention in recent years
in developing countries.
• The basic design is that of a box with a glass cover.
• The box is lined with insulation and a reflective surface is
applied to concentrate the heat onto the pots.
• The pots can be painted black to help with heat absorption.
• The solar radiation raises the temperature sufficiently to boil
the contents in the pots.

Photo Voltaic cell
Electrode
P-Type Semiconductor
N-Type Semiconductor
Reflect-Proof Film
Electrode
Solar Energy
Load
ElectricCurrent
1-1-1. Mechanism of generation
The solar cell is composed of a P-type semiconductor and an N-type
semiconductor. Solar light hitting the cell produces two types of electrons,
negatively and positively charged electrons in the semiconductors.
Negatively charged (-) electrons gather around the N-type semiconductor
while positively charged (+) electrons gather around the P-type
semiconductor. When you connect loads such as a light bulb, electric current
flows between the two electrodes.

• Direction of current inside PV cell
P
N
Current appears
to be in the
reverse direction ?
• Inside current of PV cell looks like
“Reverse direction.” Why?
?
• By Solar Energy, current is pumped up
from N-pole to P-pole.
• In generation, current appears reverse.
It is the same as for battery.
P
N
Looks like
reverse

• Voltage and Current of PV cell ( I-V Curve )
(V)
(A)
Voltage(V)
Current(I)
P
N
A
Short Circuit
Open Circuit
P
N
V
about 0.5V (Silicon)
High insolation
•Voltage on normal operation point
0.5V (in case of Silicon PV)
•Current depend on
- Intensity of insolation
- Size of cell
Low insolation
Normal operation point
(Maximum Power point)
I x V = W

• Typical I-V Curve
(V)
(A)
Voltage(V)
Current(I)
0.49 V 0.62 V
4.95A
5.55A
Depend on
type of cell or cell-
material
( Si = 0.5V )
Depend on cell-size
Depend on
Solar insolation

Crystalline
Non-crystalline
Single crystal
Poly crystalline
Amorphous
Gallium Arsenide (GaAs)
Conversion Efficiency of
Module
10 - 17%
10 - 13%
7 - 10%
18 - 30%
Conversion Efficiency =
Electric Energy Output
Energy of Insolation on cell
x 100%
Dye-sensitized Type
Organic Thin Layer Type
7 - 8%
2 - 3%
1-1-2. Various type of PV cell
• Types and Conversion Efficiency of Solar Cell
Silicon
Semiconductor
Compound
Semiconductor
Solar
Cell
Organic
Semiconductor

Photovoltaics Cells
• Mono-crystalline Solar Panels
• Polycrystalline Solar Panels.
• Amorphous Silicon
also called "Thin Film".

Photovoltaics Cells
Mono-crystalline Solar Panels
• It is the most efficient and most expensive panels
currently available.
• They are often used in applications where
installation square footage is limited, giving the end
user the maximum electrical output for the
installation area available.

Photovoltaics Cells
Polycrystalline Solar Panels
• It characterized by its shattered glass look because of
the manufacturing process of using multiple silicon
crystals.
• It has a little less efficient than mono-crystalline
panels, but also less expensive.

Photovoltaics Cells
Amorphous Silicon also called "Thin Film".
• These panels can be thin and flexible which is why
they are commonly referred to as "Thin Film" solar
panels.
• They are cheaper and are not affected by shading.
• Drawbacks are
loss of wattage per sq. ft. installed
low efficiency; and
heat retention.

• Crystal cell (Single crystal and Poly crystalline Silicon)
Single crystal Poly crystalline
Formed by melting high purity silicon
like as Integrated Circuit
For mass production, cell is sliced from
roughly crystallized ingot.

• Surface of PV cell
Front Surface
(N-Type side)
• Aluminum Electrode
(Silver colored wire)
• To avoid shading,
electrode is very fine.
Anti reflection film
(Blue colored film)
• Back surface is P-type.
• All back surface is
aluminum electrode
with full reflection.
Example of Poly Crystalline PV

Single crystal Poly crystalline
120W
(25.7V ,
4.7A)
1200mm
800mm800mm
1200mm
• PV Module (Single crystal, Poly crystalline Silicon)
(3.93ft)
（2.62ft）
（3.93ft）
(2.62ft)
128W
(26.5V ,
4.8A)
Efficiency is higher
Cost high
Efficiency is lower
Cost low
Same size

• Hierarchy of PV
2 – 3 W
100 - 200 W
10 - 50 kW
Cell
Array
Module,Panel
Volt Ampere Watt Size
Cell 0.5V 5-6A 2-3W about 10cm
Module 20-30V 5-6A 100-200W about 1m
Array 200-300V 50A-200A 10-50kW about 30m
6x9=54 (cells) 100-300 (modules)

•Roughly size of PV Power Station.
How much PV can we install in this conference room?
1 kw PV need 10 m2 Please
remember
10m(33feet)
20m(66feet)
Conference
Room
(We are now)
Our room has about 200 m2
We can install about
20 kW PV in this room
(108 feet2)
(2,178 feet2)

1-1-3. Installation example
• Roof top of residence ( Grid connected )
Most popular installation style
in Japan.
Owner can sell excess
power to power utility.

• Roof top of school ,community-center building.
(For education and emergency power)

• Distant and independent power supply ( Off grid )
Transmit station on top of mountain
Advertising sign beside highway

• Mountain cottage ( Off grid )
1.2kW system
Inverter and controller

1-1-4. Basic Characteristic
• I / V curve and P-Max control
P
N
A
V
• To obtain maximum power, current
control (or voltage control) is very
important.
(V)
(A)
Voltage(V)
Current(I)
I x V = W
P2
PMAX
P1
Vpmax
Ipmax
I/V curve
P- Max control
• “Power conditioner” (mentioned
later) will adjusts to be most suitable
voltage and current automatically.
Power curve

• Estimate obtained power by I / V curve
(V)
(A)
Voltage(V)
Current(I)
12
10
8
6
4
2
0
0 0.1 0.2 0.3 0.4 0.5 0.6
P
N
A
)(05.0 R
PV character
( I/V curve )
If the load has 0.05 ohm resistance,
cross point of resistance character and
PV-Character will be following point.
Then power is 100x0.05=5 W
)(05.0 R
05.0/VI 
R
V
I 
Ohm’s theory

• I / V curve vs. Insolation intensity
P
N
P
N
Mismatch
5A
1A
P
N
P
N
Bypass
Diode
5A
1A 4A
(V)
(A)
Current(I)
High intensity insolation
Low intensity insolation
I x V = W
5A
1A
•Current is affected largely by change
of insolation intensity.
•Partially shaded serial cell will produce
current mismatch.
Bypass Diode

• Temperature and efficiency
4
6
8
10
12
14
0 10 20 30 40 50 60 70 80 90 100
Module Temperature (deg.C)
Efficiency(%)
Crystalline cell
Amorphous cell
Typical
(25C)
Summer time
on roof top
(65C)
2%
down
•When module temperature rises up, efficiency decreases.
•The module must be cooled by natural ventilation, etc.

1-1-5. Case sturdy
1.Maximum power control
P
N
P
N
P
N
)(05.0 R
)(10.0 R
)(02.0 R
Q : Calculate how much power you can get by following three
resistance. ( I / V curve is next page)

1-1-5. Case sturdy
1.Maximum power control
(V)
(A)
Voltage(V)
Current(I)
12
10
8
6
4
2
0
0 0.1 0.2 0.3 0.4 0.5 0.6
R
V
I 
I/V curve of current insolation.

1-1-5. Case sturdy
2.Temperature vs. Efficiency
Q: There is 50 kW Crystalline PV system.
If surface temperature rises from 25ºC to 65ºC, How much the
capacity will be?

Hybrid solar technology
• Solar hybrid power systems are hybrid power systems that combine
solar power from a photovoltaic system with another power
generating energy source.
• A common type is a photovoltaic diesel hybrid system, combining
photovoltaics (PV) and diesel generators, as PV has hardly any marginal
cost and is treated with priority on the grid.
• The diesel generators are used to constantly fill in the gap between the
present load and the actual generated power by the PV system.
• As solar energy is fluctuating, and the generation capacity of the diesel
generators is limited to a certain range, it is often a viable option to
include battery storage in order to optimize solar's contribution to the
overall generation of the hybrid system.
• The best business cases for diesel reduction with solar and wind energy
can normally be found in remote locations because these sites are
often not connected to the grid and transport of diesel over long
distances is expensive.
• Many of these applications can be found in the mining sector [6] and on
islands By Prof. Ghada Amer3/26/2018 55

Solar PV Systems - Solar Lighting &
Electricity

CO2 Capture and Storage
• Why do we Need CO2 Capture and Storage?
 By 2050, global population will rise from 7 to 9 billion
people
 World energy demand is expected to increase by 50%
over the next 20 years
97 billion people
CCS is an essential part of the portfolio of technologies
needed to achieve substantial global emissions reductions.

 Fossil fuels (coal, gas and oil)
represent 81%
of the global energy mix
 Renewables only account
for 13% of our total energy supply
Fossil Fuels
81.1%Renewables
13%
Nuclear
5.9%

 Renewables
could make up 30%
of the global energy mix.
30%
Estimated share of
renewables by 2030
By 2030
Unfortunately, fossil fuels will
remain our main source of energy
for decades to come.

• Fossil Fuels Power the Largest Emitters of
• too Much CO2 Leads to Global Warming which
in turn, produces climate change.
Fossil fuels power plants,
heavy industry and refineries
account for 52% of the world’s
current CO2 emissions
(15 billion tones CO2
emissions/year)
CO2

• How do we Meet this Challenge?

• How do we Meet this Challenge?
• CCS alone will provide up to 20% of the CO2
emission reductions we need to make by 2050.

• How it works?
We can capture
at least 90% of
emissions from
fixed emitters
We have been
transporting CO2
for decades
CO2 can be stored safely
and permanently using
natural trapping
mechanisms

• CO2 capture and storage is the term used to describe a
set of technologies aimed at capturing carbon dioxide
emitted from industrial and energy-related sources
before it enters the atmosphere, compressing it, and
injecting it deep underground in secure geological
formations, and ensuring it remains stored there
indefinitely.

The CO2 can be captured either from the
flue gases, or is the carbon captured from
the fuel before the combustion process.
The CO2 is cleaned and compressed. Then
it is pumped as a liquid down into a
porous rock formation for permanent
storage.

• Pre-combustion:
Where CO2 is captured before fuel is burned
• Oxy-fuel:
Where CO2 is captured during fuel combustion
• Post-combustion:
Where CO2 is captured after fuel has been
burned
(This technology can also be retrofitted to existing power and industrial plants)
There are 3 technologies to capture CO2 :

Pre-combustion
CO2 is captured
before fuel is burned

Oxy-fuel
CO2 is captured during
fuel combustion

Post-combustion
CO2 is captured
after fuel has been burned

CO2Transport
• Once captured, the CO2 is compressed into a liquid
state and dehydrated for transport and storage
• CO2 is preferably transported by pipeline
• …or by ships when a storage site is too far from the
CCS capture plant

Safely Storing CO2
• We use a natural mechanism that has trapped
CO2, gas and oil for millions of years
• Liquid CO2 is pumped deep underground into one
of two types of reservoirs:
– deep saline aquifers (700m-3,000m)
– depleted gas and oil fields (up to 5,000m)
• Both types of reservoirs have a layer of porous
rock to absorb the CO2 and an impermeable layer
of cap rock to seal the porous layer

The liquid CO2 is pumped deep
underground into one of two types
of CO2 storage reservoir (porous
rock)
Cap rock
Cap rock
Deep saline
aquifer
700m -
3,000m
up to 5,000m
Depleted oil and gas
fieldsBy Prof. Ghada Amer3/26/2018 74

3 chapter 3 solar energy

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