ELEG 620 Lecture 1
Solar
S
l Radiation
R di ti (1)
2010/02/16
Outline
1. Spectral irradiance
(1) What is that and why we care?
(2) How to express?
(3) How to use the two expressions?
2. Solar radiation
(1) Treat the sun as a blackbody: power, spectrum...
(2) Solar radiation in space: How to calculate the power density on a plate
given the distance away from the sun? (not considering the
atmospheric effect)
3. Atmospheric effect
(1) What is that?
(2) Th
The iinfluence
fl
on th
the light
li ht striking
t iki on th
the earth?
th? S
Spectrum,
t
power, and
d
direction.
(3) How to quantify the reduction of the light when passing through the
atmosphere?
Outline
1. Spectral irradiance
(1) What is that and why we care?
(2) How to express?
(3) How to use the two expressions?
2. Solar radiation
(1) Treat the sun as a blackbody: power, spectrum...
(2) Solar radiation in space: How to calculate the power density on a plate
given the distance away from the sun? (not considering the
atmospheric effect)
3. Atmospheric effect
(1) What is that?
(2) Th
The iinfluence
fl
on th
the light
li ht striking
t iki on th
the earth?
th? S
Spectrum,
t
power, and
d
direction.
(3) How to quantify the reduction of the light when passing through the
atmosphere?
Spectral irradiance: concepts
Spectral irradiance: how to express
ASTM G173 Global
1.8
-1
1.2
po
ower density (W**m *nm )
1.4
-2
1.6
1.0
0.8
0.6
0.4
0.2
0.0
0
500
1000
1500
2000
2500
wavelength
l
th (nm)
( )
3000
3500
4000
4500
Spectral irradiance: how to express
ASTM G173 Global
photton flux (#*m-2 *s
sec -1*nm-1)
6.E+18
6
8
5.E+18
4.E+18
3.E+18
2.E+18
1.E+18
0.E+00
0
500
1000
1500
2000
2500
wavelength
l
th (nm)
( )
3000
3500
4000
4500
Spectral irradiance: how to express
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Spectral irradiance: how to use
accumulated power of ASTM G173 Global
acc
cumulated power (W*m -2)
1000
800
600
400
200
0
0
500
1000
1500
2000
2500
wavelength (nm)
3000
3500
4000
4500
Spectral irradiance: how to use
accumulated current density for fully absorption
off ASTM G173
G1 3 Global
Gl b l
accum
mulated current d
density
-2
(A*m )
800
700
600
500
400
300
200
100
0
0
500
1000
1500
2000
2500
wavelength (nm)
3000
3500
4000
4500
Outline
1. Spectral irradiance
(1) What is that and why we care?
(2) How to express?
(3) How to use the two expressions?
2. Solar radiation
(1) Treat the sun as a blackbody: power, spectrum...
(2) Solar radiation in space: How to calculate the power density on a plate
given the distance away from the sun? (not considering the
atmospheric effect)
3. Atmospheric effect
(1) What is that?
(2) Th
The iinfluence
fl
on th
the light
li ht striking
t iki on th
the earth?
th? S
Spectrum,
t
power, and
d
direction.
(3) How to quantify the reduction of the light when passing through the
atmosphere?
Solar
S
l radiation
di ti model:
d l
blackbody radiation
Solar radiation in space
Outline
1. Spectral irradiance
(1) What is that and why we care?
(2) How to express?
(3) How to use the two expressions?
2. Solar radiation
(1) Treat the sun as a blackbody: power, spectrum...
(2) Solar radiation in space: How to calculate the power density on a plate
given the distance away from the sun? (not considering the
atmospheric effect)
3. Atmospheric effect
(1) What is that?
(2) Th
The iinfluence
fl
on th
the light
li ht striking
t iki on th
the earth?
th? S
Spectrum,
t
power, and
d
direction.
(3) How to quantify the reduction of the light when passing through the
atmosphere?
Atmospheric
At
h i effect:
ff t
Influence by the earth’s atmosphere
Atmospheric
At
h i effect:
ff t
spectrum, power, and direction
Atmospheric
At
h i effect:
ff t
Air Mass (AM)
Atmospheric
At
h i effect:
ff t
Air Mass (AM)
Outline
1. Spectral irradiance
(1) What is that and why we care?
(2) How to express?
(3) How to use the two expressions?
2. Solar radiation
(1) Treat the sun as a blackbody: power, spectrum...
(2) Solar radiation in space: How to calculate the power density on a plate
given the distance away from the sun? (not considering the
atmospheric effect)
3. Atmospheric effect
(1) What is that?
(2) Th
The iinfluence
fl
on th
the light
li ht striking
t iki on th
the earth?
th? S
Spectrum,
t
power, and
d
direction.
(3) How to quantify the reduction of the light when passing through the
atmosphere?