Solar radiation

1. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 1
01/08/2011
Solar Radiation
Lecture #5

2. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 2
01/08/2011
Learning Objective and Outcome sheet
Topic Solar radiation
Learning Objectives
Losses of solar radiation in the atmosphere
Types of available solar radiation on the earth surface
Measurement of different types of radiation on earth surface
Estimation of total radiation falling on any surface
Learning Outcome
Extinction coefficient of earth surface and air mass.
Global, beam, diffuse, and reflected radiation
Pyranometer, Pyrheliometer, Sunshine recorder
Tilt factors for beam, diffuse and reflected radiaon
Problem/Assignment
Learning Resources
Summary
This lecture enables learner to understand the losses occurred in the
atmosphere and the total radiation available on any surface on the
earth. Different instruments can be deployed for the measurement
of the solar radiation is discussed. The importance of determining
the position of the sun in the sky is discussed.

3. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 3
01/08/2011
Types of solar radiation on earth
Direct

4. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 4
01/08/2011
Global solar radiation
Ib
Ir
Id
flected
Diffuse
Beam
GlobalRadiation Re




5. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 5
01/08/2011
Global radiation on a tilt surface
 
h
d
h
b
r
h
d
d
h
b
b
G I
I
r
I
r
I
r
I ,
,
,
, 




6. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 6
01/08/2011
Global radiation on a tilt surface
reflection
ground
for
factor
Tilt
r
radiation
diffuse
for
factor
Tilt
r
radiation
beam
for
factor
Tilt
r
r
d
b



 
h
d
h
b
r
h
d
d
h
b
b
G I
I
r
I
r
I
r
I ,
,
,
, 




7. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 7
01/08/2011
Global radiation on a tilt surface
surface
surface
,
,
horizontal
on
radiation
diffuse
I
horizontal
on
radiation
beam
I
h
d
h
b


 
h
d
h
b
r
h
d
d
h
b
b
G I
I
r
I
r
I
r
I ,
,
,
, 




8. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 8
01/08/2011
Global radiation on a tilt surface
 
  ty
reflectivi
Ground
r
r
r
r
d
z
b
:
,
2
cos
1
2
cos
1
cos
cos











 
h
d
h
b
r
h
d
d
h
b
b
G I
I
r
I
r
I
r
I ,
,
,
, 




9. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 9
01/08/2011
Global radiation on a tilt surface
 
h
d
h
b
r
h
d
d
h
b
b
G I
I
r
I
r
I
r
I ,
,
,
, 



h
d
h
b
h
G
r
d
b
I
I
I
Hence
r
and
r
r
surface
horizontal
For
,
,
,
,
0
,
1
,
1
0
:





 

Pyranometer is placed horizontally to discard the
reflected radiation from ground

10. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 10
01/08/2011
Measurement of solar radiation
Pyrheliometer
Pyranometer
Source:
http://en.wikipedia.org/wiki/Pyranometer

11. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 11
01/08/2011
Measurement of solar radiation
Pyranometer for
Global radiation
Direct radiation
Diffuse radiation

12. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 12
01/08/2011
Thermopile
sensor Glass
domes
leveling
feet
PCB
level
Level
Pyranometer schematic
Source:
http://en.wikipedia.org/wiki/Pyranometer

13. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 13
01/08/2011
Pyranometer shade ring
Source:
http://en.wikipedia.org/wiki/Pyranometer

14. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 14
01/08/2011
Sun shine recorder
Glass sphere
Recorder

15. IIT Bombay
DESE
EN 601: Lecture 5: Solar Radiation Slide 15
01/08/2011
Pyrheliometer
It measures only beam or direct
radiation with a small aperture
(View = 5
o
)