Module 2.1 - Unit 1.pptx

UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Always a Pioneer, Always Ahead
1

2
UNIT 1 INTRODUCTION TO SOLAR ENERGY
UNIT 2 SOLAR PHOTOVOLTAIC

What is Solar Energy?
 Originates with the
thermonuclear fusion
reactions occurring in
the sun.
 Represents the entire
electromagnetic
radiation (visible light,
infrared, ultraviolet, x-
rays, and radio waves).

Solar Energy – A Bright Idea!
“I’d put my money on the sun and solar energy. What a source of
power! I hope we don’t have to wait ‘til oil and coal run out
before we tackle that.”
- Thomas Edison

People have been harnessing solar energy for a long time!
Solar collector for
heating water
A home in California in 1906

Advantages and Disadvantages
 Advantages
• All chemical and radioactive polluting byproducts of the thermonuclear
reactions remain behind on the sun, while only pure radiant energy
reaches the Earth.
• Energy reaching the earth is incredible. By one calculation, 30 days of
sunshine striking the Earth have the energy equivalent of the total of all
the planet’s fossil fuels, both used and unused!
 Disadvantages
• Sun does not shine consistently.
• Solar energy is a diffuse source. To harness it, we must concentrate it
into an amount and form that we can use, such as heat and electricity.
• Addressed by approaching the problem through:
1) collection, 2) conversion, 3) storage.

How much solar energy?
The surface receives about 47% of the total
solar energy that reaches the Earth. Only this
amount is usable.

SOLAR COURSE: SEASONS

SOLAR COURSE: PATH OF THE SUN

SOLAR COURSE: SUN ANGLES

POSITION OF THE SUN
 Sun height, height angle,
solar altitude angle or
elevation  S
 This is the angle between a
line that points from the site
towards the centre of the
sun, and the horizon.
 The zenith angle is the
opposite angle to the sun
height (90°  - S). At a sun
height of 90°, the sun is at
the zenith and the zenith
angle is therefore zero.

POSITION OF THE SUN
 Sun azimuth S
 The sun azimuth S is
the angle, measured
clockwise, between
geographical North and
the point on the
horizon directly below
the sun (at the end of a
line running from the
centre of the sun to the
horizon).

POSITION OF THE SUN
 (Another definition is
sometimes used,
whereby the
definition of the sun
height remains the
same but the sun
azimuth is counted as
zero when the sun is
in the South and
measured
anticlockwise.
Sometimes the
symbols of azimuth
and sun height are
also interchanged.)

OPTIMAL SOLAR SYSTEM ORIENTATION
 The figure visualizes
the sun angles, azimuth
and tilt angle to define
the position of a tilted
surface. The angle of
incidence q depends on
all these angles. As
mentioned above, the
maximum irradiance
can usually be obtained
by a surface that is
perpendicular to the
sun.

 Since the position of
the sun changes
during the day and
year, only a two-axis
tracked surface gets
the maximum
irradiation. There, the
annual irradiation can
be more than 30%
higher than at a non-
tracked surface.

 A one-axis tracked surface
has an irradiation gain in
the range of 20%. Near
the equator, the optimal
orientation of a non-
tracked surface is nearly
horizontal. In the Northern
Hemisphere, it should be
tilted towards the south,
and in the southern
hemisphere, towards the
north. The optimal tilt
angle increases with
higher latitudes, and is
higher in winter than in
summer.

SOLAR COURSE: SUN CHARTS

SOLAR COURSE
SUN CHART WITH HORIZON
Sun charts
 manual or
computerised
 simulate the
skyline of the
surroundings
 determine periods
of (partial) shading
(and/or reduced
diffuse irradiation)
FUNDAMENTALS 05

AVAILABLE ENERGY
ATMOSPHERIC TRANSMISSION
 direct and diffuse
 part of light absorbed and
scattered by the earth’s
atmosphere:
– water vapour
– dust
– ozone
– a.o.
solar radiation: spectrum of wavelengths between 0.4 and 3.5 m

AVAILABLE ENERGY: LATITUDE & CLIMATE
Monthly amount of solar energy varies depending on season and location (factor 5 -
10)
Yearly amount of solar energy varies depending on location (factor 3-4)
Intensity and colour
content of irradiation
is function of:
•length of path through the
atmosphere
•absorption and scattering

AVAILABLE ENERGY: SPECTRUM
Light reaching the earth varies considerably
(intensity, colour content, direction)
Air Mass (AM)
indicates the (effective) path
length the light has travelled
through the atmosphere
AM 1
one atmospheric thickness
AM 1.5
typically used in measurements

Extraterrestrial and terrestrial spectrum of sunlight

COLLECTED ENERGY: TILT & ORIENTATION
Maximal annual yield
 Southern orientation (or
Northern one in the
Southern hemisphere)
 optimal tilt of PV depends
on the latitude and local
meteorological conditions
 adjustable tilt according
the year season

COLLECTED ENERGY
DIRECT & INDIRECT RADIATION
Optimal tilt angle of PV array
direct sunlight
 equals latitude of the location
indirect / diffuse sunlight
 (close to) horizontal
total sunlight
 intermediate value
tilt angle can be compromised due
to architectural reasons

IRRADIANCE, IRRADIATION AND ILLUMINANCE
 Various different terms are used when dealing with solar
radiation. However, these terms are often used
incorrectly, even by some solar specialists.

 The total specific radiant power, or radiant flux,
per area that reaches a receiver surface is called
irradiance. Irradiance is measured in W/m2 and
has the symbol E. When integrating the irradiance
over a certain time period it becomes solar
irradiation. Irradiation is measured in either J/m2
or Wh/m2, and represented by the symbol H.
 .

 For daylighting purposes, only the visible part of the
sunlight is considered. The analogous quantity to the
irradiance for visible light is the illuminance. This uses the
unit lm/m2 (lumen/m2) or lx (lux).

DIRECT AND DIFFUSE IRRADIANCE
 Other atmospheric particles
reflect or scatter sunlight. Only
a part of the extraterrestrial
beam irradiance reaches the
earth's surface directly.The
scattered part of the
irradiance has no direction.
Only direct irradiance can be
used for concentrating solar
systems, but non-
concentrating systems can also
use the scattered, or diffuse
irradiance

 The so-called global
irradiance Eg on a
horizontal surface on
earth consists of the
direct Edir and diffuse
irradiance Edif.

INSTRUMENTS
Sensors for solar irradiance
measurements (clockwise
from top) - Pyranometer
with thermal sensor for
global irradiance
measurements, Two-axis
tracked pyrheliometer for
direct normal irradiance
measurements,
Pyranometer with shading
ball for diffuse irradiance
measurements

33

Module 2.1 - Unit 1.pptx

Recommended

Recommended

More Related Content

Similar to Module 2.1 - Unit 1.pptx

Similar to Module 2.1 - Unit 1.pptx (20)

Recently uploaded

Recently uploaded (20)

Module 2.1 - Unit 1.pptx