# Lecture 2 - Sun - Earth Geometry Notes

## : Lecture 2 - Sun - Earth Geometry Notes

``` Page 1

Solar Energy Technology - 2

V.V.Satyamurty
Professor of Mechanical Engineering
INDIAN INSTITUTE OF TECHNOLOGY
Kharagpur 721302, INDIA

Page 2

Solar Energy Technology - 2

V.V.Satyamurty
Professor of Mechanical Engineering
INDIAN INSTITUTE OF TECHNOLOGY
Kharagpur 721302, INDIA

Lecture 2 Sun - Earth Geometry

Page 3

Solar Energy Technology - 2

V.V.Satyamurty
Professor of Mechanical Engineering
INDIAN INSTITUTE OF TECHNOLOGY
Kharagpur 721302, INDIA

Lecture 2 Sun - Earth Geometry

Sun

Dia. = 1.39 ? 10
9
m
= 8.64 ? 10
5
mi

32 ?

Ea rth

127 ? 10
7
m
7900 mi

Solar constant

= 1353 W/m
2

= 428 Btu/ft
2
hr
= 4871 MJ/m
2
hr

G
sc

Distance is

1.495 ? 10
11
m

9.3 ? 10
7
mi

?1.7%

SOLAR CONSTANT
G
sc
, = 1377 W/m
2

Page 4

Solar Energy Technology - 2

V.V.Satyamurty
Professor of Mechanical Engineering
INDIAN INSTITUTE OF TECHNOLOGY
Kharagpur 721302, INDIA

Lecture 2 Sun - Earth Geometry

Sun

Dia. = 1.39 ? 10
9
m
= 8.64 ? 10
5
mi

32 ?

Ea rth

127 ? 10
7
m
7900 mi

Solar constant

= 1353 W/m
2

= 428 Btu/ft
2
hr
= 4871 MJ/m
2
hr

G
sc

Distance is

1.495 ? 10
11
m

9.3 ? 10
7
mi

?1.7%

SOLAR CONSTANT
G
sc
, = 1377 W/m
2

E
sun
= ? A
s
T
4
W
?= 5.67 x 10
-8
W/(m
2
K
4
)
The variation in the total radiation emitted by
sun is less than ? 1.5 %

EXTRA TERRESTRIAL NORMAL
Page 5

Solar Energy Technology - 2

V.V.Satyamurty
Professor of Mechanical Engineering
INDIAN INSTITUTE OF TECHNOLOGY
Kharagpur 721302, INDIA

Lecture 2 Sun - Earth Geometry

Sun

Dia. = 1.39 ? 10
9
m
= 8.64 ? 10
5
mi

32 ?

Ea rth

127 ? 10
7
m
7900 mi

Solar constant

= 1353 W/m
2

= 428 Btu/ft
2
hr
= 4871 MJ/m
2
hr

G
sc

Distance is

1.495 ? 10
11
m

9.3 ? 10
7
mi

?1.7%

SOLAR CONSTANT
G
sc
, = 1377 W/m
2

E
sun
= ? A
s
T
4
W
?= 5.67 x 10
-8
W/(m
2
K
4
)
The variation in the total radiation emitted by
sun is less than ? 1.5 %

EXTRA TERRESTRIAL NORMAL

G
on
= G
sc
( 1 + 0.033 cos[360n/365] )
n is the day of the year, i.e., the sequential
number of the day counting January 1 as 1.

Sun is at an effective temperature of 5772 K.
The solar constant is 1377 W/m
2
.
``` Use Code STAYHOME200 and get INR 200 additional OFF