cap02-Sun and radiation

Architecture and solar energy Energy and environment

by Moisès Morató

Sun, earth and radiation

Architecture and solar energy Energy and environment

by Moisès Morató

R= 6.400 Km

R= 700.400 Km

150.000.000 Km

The sun and the earth

SUN EARTH

Architecture and solar energy Energy and environment

by Moisès Morató

R= 6.400 Km

R= 700.400 Km

EARTH

Architecture and solar energy Energy and environment

by Moisès Morató

R= 700.400 Km

EARTH

Architecture and solar energy Energy and environment

by Moisès Morató

R= 6.400 Km

R= 700.400 Km

Architecture and solar energy Energy and environment

by Moisès Morató

0,53º (2D) 0,00027 Sr (3D)

22.995 “suns” / hemisphere

The sky can be filled by near 23.000 suns.

Architecture and solar energy Energy and environment

by Moisès Morató

Solar radiation.

Architecture and solar energy Energy and environment

by Moisès Morató

R= 6.400 Km

R= 700.400 Km

The power of sun:

1.400 W/m2 of power at 150 milions of Km

570.000.000 ton de H2 a 560.000.000 ton de He per second =

400.000.000.000.000.000.000 de MW

Architecture and solar energy Energy and environment

by Moisès Morató

Absolut radiation of the estratosferic radiation in the earth:

1. 4 0 0 W / m2 o f p o w e r

Architecture and solar energy Energy and environment

by Moisès Morató

The movement of earth around the sun.

Architecture and solar energy Energy and environment

by Moisès Morató

Inclination of axis of rotation

N

S

1 rev. at day

Source: M. Morató.

E W

Architecture and solar energy Energy and environment

by Moisès Morató

Inclination of axis of rotation

N

S 23,45º E c l i p t i c p l a n e

1 rev. at day

Source: M. Morató.

I n c l i n a t i o n o f a x i s :

Constant = 23,45º

E

W

Architecture and solar energy Energy and environment

by Moisès Morató

1 revolution every 365’25 days

1 revolution every day

The seasons

day/night

Image: M. Morató.

E c l i p t i c p l a n e

Architecture and solar energy Energy and environment

by Moisès Morató

Declination

N

S

+ 23,45º

E c l i p t i c

p l a n e

Source: M. Morató.

N

S - 23,45º

S u m m e r W i n t e r

Architecture and solar energy Energy and environment

by Moisès Morató

Declination

Source: M. Morató.

+ 23,45 º

- 23,45 º

0 º 0 º

+ 23,45 º

Architecture and solar energy Energy and environment

by Moisès Morató

The seasons

Source: M. Morató.

summer (north hemispheri) winter (north hemispheri)

Architecture and solar energy Energy and environment

by Moisès Morató

The seasons

Position in summer (north hemispheri) at 12:00 at noon

Source: M. Morató.

Architecture and solar energy Energy and environment

by Moisès Morató

The seasons

Position in summer (north hemispheri) 12:00 midnight

Source: M. Morató.

Architecture and solar energy Energy and environment

by Moisès Morató

The seasons

Position in winter (north hemispheri) in the 12:00 at noon

Source: M. Morató.

Architecture and solar energy Energy and environment

by Moisès Morató

The seasons

Position in winter (north hemispheri) at 12:00 midnight

Source: M. Morató.

Architecture and solar energy Energy and environment

by Moisès Morató

Which is the movement of the Sun from the Earth ?

Source: M. Morató.

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

The Cercasol tool (findsun)

The movement of the Sun from the earth

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

ex: How to follow the sun in BCN ?

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

1.- Put the axis in direction North

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

2.- Inclinate the axis = latitude of place = 41º

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

3.- Incline the arrow = declination of the day

N= day of year (N =1 of January)

Architecture and solar energy Energy and environment

by Moisès Morató

Soltice of summer (21 June)

Source: M. Morató.

Equinox spring and autumn (21 March/ 22 September)

Soltice of winter (21 december)

declination (+ 23,45º) declination (0º) declination (- 23,45º)

The 3 special positions of the year

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

4.- Rotate (left rotation): 1 revolution at day.

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

South

Polar

latitude

1 turn at day

summer

winter

spring-autumn

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

declination (- 23,45º)

South

West

Est

North

12:00 solar (Noon) Ex: Track on solstice of

winter (41 º lat North)

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

declination (0º)

12:00 solar (Noon) Ex: Track on equinocces (41º

Lat North)

South West

Est North

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

12:00 solar (Noon)

Ex: Track on solstice of summer (41 º lat North)

South West

Est

North

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

Ex: Position of the “Cercasol” at 23 of December in others places on the earth

N

S

N

S

N

S

N

S S

Architecture and solar energy Energy and environment

by Moisès Morató

The nature of the radiation on earth

Source: M. Morató.

Architecture and solar energy Energy and environment

by Moisès Morató

Radiation Power

Source: M. Morató.

Radiation Energy

W / m2 kWh / m2 units

mean Instantaneous energy

captured energy in a interval of time

Power (W/m2)

Time (s) t1 t2

X (W/m2) Z (kWh/m2)

t2

Meaning of power and energy radiation

Power at time t2 is Energy captured between time t1

and t2 is

Architecture and solar energy Energy and environment

by Moisès Morató Architecture and solar energy

1. 4 0 0 W / m2 o f p o w e r

Image: Google earth.

Sun, earth and radiation

The nature of the radiation on earth

Architecture and solar energy Energy and environment

by Moisès Morató

λ (µm)

visible IR UV

S h o r t w a v e

Distribution of the solar radiation spectrum:

0,5 1,0 1,5 2,0 2,5 3,0

Intensity

0,4 0,7

1. 4 0 0 W / m2 o f s o l a r p o w e r

Architecture and solar energy Energy and environment

by Moisès Morató

Stratospheric radiation and Radiation at level of the sea in a clear day

1. 4 0 0 W / m2 o f p o w e r

Image: Google earth.

9 0 0 W / m2 o f p o w e r

1.400 W/m2

900 W/m2

4% 48% 48%

2% 40% 58%

Architecture and solar energy Energy and environment

by Moisès Morató

Source: www.oksolar.com.

Architecture and solar energy Energy and environment

by Moisès Morató

Source: www.oksolar.com.

Average daily radiation on the earth: 170 W/m2/day = 4 kWh/m2/day

7,2 kWh/m2

4,8 kWh/m2

2,5 kWh/m2

4,4 kWh/m2

3,9 kWh/m2

< 2 kWh/m2

Architecture and solar energy Energy and environment

by Moisès Morató

Source: NASA.

0

4

8

0

4

8

0

4

8

0

4

8

0

4

8

0

4

8

0

4

8

J F M A M J J A S O N D

Theoretical distribution of monthly radiation by latitude (kWh/m2/day)

+ 90º

+ 60º

+ 30º

+ 0º

- 30º

- 60º

- 90º

+ 90º

+ 60º

+ 30º

+ 0º

- 30º

- 60º

- 90º

Architecture and solar energy Energy and environment

by Moisès Morató

Source: NASA.

Direct and diffuse radiation

Architecture and solar energy Energy and environment

by Moisès Morató

Source: Traimar

Direct and diffuse radiation

Source of diffuse radiation

Source of reflected radiation

Source of direct radiation (sun)

Architecture and solar energy Energy and environment

by Moisès Morató

Source: Traimar

Global radiation

Direct rad.

Diffuse rad.

Reflected rad.

+

+

=

Architecture and solar energy Energy and environment

by Moisès Morató

Source: Traimar

Global radiation

Direct rad.

Diffuse rad. +

Reflected rad.

+

Usually reflected radiation is lower than direct and diffuse radiation then …

=

Architecture and solar energy Energy and environment

by Moisès Morató

Source: Google.

In the atmosphere appears the diffuse radiation

Diffuse radiation

Architecture and solar energy Energy and environment

by Moisès Morató

Source: Google

Diffuse radiation appears by interaction of direct radiation against atmosphere molecules

Direct and diffuse radiation

Architecture and solar energy Energy and environment

by Moisès Morató

Direct and diffuse radiation in a homogeneous clouded sky

100 %

Source: Moisès Morato. www.cercasol.com

Architecture and solar energy Energy and environment

by Moisès Morató

Direct and diffuse radiation (W/m2) in homogeneous clouded skies

100 % 80 % 60 %

40 % 20 %

A B C

D E

Source: Moisès Morato. www.cercasol.com

Architecture and solar energy Energy and environment

by Moisès Morató

0

1

2

3

4

5

6

7

8

9

A (100 %) B (80 %) C (60 %) D (40 %) E (20 %)

Irrad

iatio

n (k

Wh/

m2/d

ay)

Source: M. Morató. www.cercasol.com.

Evolution of direct and diffuse radiation (kWh/m2/day) in homogeneous clouded skies

Architecture and solar energy Energy and environment

by Moisès Morató

Source: UAB (Universitat de Física)

Real graphs of direct and difusse radiation

A fully clear day (june 2006 BCN)

Architecture and solar energy Energy and environment

by Moisès Morató

Real graphs of direct and difusse radiation

clear day cloudy day Source: UAB (Universitat de Física)

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

Intensity of diffuse radiation in sky can be higher o lower than the sky without clouds.

Diffuse radiation

Architecture and solar energy Energy and environment

by Moisès Morató

Source: M. Morató.

Intensity of diffuse radiation in sky can be higher o lower than the sky without clouds.

Diffuse radiation