Fundamentals of Solar Energy
The sun is an average star, is estimated to have a life of five billion years. It has a radius of 700,000 Km. With a solar mass of 330,000 times the mass of Earth. On the outside of the fusion it emits energy as E = mc2 occurs. He is considered an ideal black body, which is one that absorbs energy and emits all the energy you have.
The maximum intensity at a point on the Earth is 1.4 kW / m2 if this ideal, that is, if the road is not lost anything.
Sun waves as electromagnetic waves arrive as photons are propagated at the speed of light e = 300,000 km / sec. Lightning will take about 8 minutes to reach Earth. Every second the sun releases energy 4 October 26 Joules. He is considered a constant temperature of 5900 Kelvin. Emitting at different wavelengths and these are depending ultraviolet rays, visible light and infrared rays.
The intensity of the radiation reaching the outside of the Earth's atmosphere known as solar constant (G). It is not a constant value since the distance between the Sun and Earth neither is, and that intensity is dependent on the distance. Ranging in value between 1400 and 1310 w / m2, taking as value set 1353 w / m2. However, after passing through the atmosphere it is quantified solar constant is 1100 W / m2.
On the surface of the earth will reach three types of radiation:
Direct radiation - is the one that reaches Earth in a straight line from the solar circle.
diffuse radiation - is diffused and scattered by colliding with the atmosphere. Undergoes many changes of direction, it gives the feeling that comes from the sky. It is capable of reaching a surface but not exposed to the sun.
Albedo radiation - comes from nearby bodies (eg a building). There is usually considered for calculation purposes because it has a negligible value.
Some effects produced by solar radiation are for example the color of the sky. It is blue by the shock of radiation with molecules of nitrogen and oxygen. At dusk and dawn, the sun's rays reach more oblique so the amount of air to pass through is greater, for that reason is reddish.
The total radiation is the sum of all radiations. The radiation does not come to the same extent, even the direct and diffuse.
The energy reaching a surface:
-irradiation (E) - is the total amount of energy in the form of radiation reaching an area determined within a set time. In S.I. the unit is the joule.
-Irradiancia (I) - is the incident energy per unit time and area. In S.I. It measured in W / m2.
Logically the energy due to direct radiation that can intercept an exposed to sunlight surface depends on the angle of the same with the rays.
I '= I cos . α
The radiation meter device called radiometer.
Astronomy solar position
Earth rotates around the sun and take to give a full 365 years back. In the region between the orbit of the Earth and the Sun it is called the ecliptic. It rotates on itself slow to give a full 24 hours back. The reason the hours of sunshine are highest in summer as well as leading to the seasons is that the Earth's axis is offset about 23'5º. This does not affect the distance to the sun.
When we look at the sun, we see that appears in the east and sets in the west. Also does not have the same height in winter than in summer, so to indicate the position of the sun would have to give two coordinates are azimuth, which is the angle between the position of the sun relative to the south and the solar height, which is the angle between the sun's position relative to the horizontal surface.
The collectors should be oriented towards the south because that would affect the sun virtually all day. If this is not possible, we should choose the most favorable with minor deviations of 25%.
To see the shadow of the collectors or an obstacle we must take into account the winter solstice because it is when the sun is lower and more shade occurs.
With regard to the inclination of the collectors, should be to make the sun's rays impinge as vertical as possible in the collector, so that should be tilted. This inclination varies according to the latitude of ± 10% .
About the Author:
The writer Danilo hasan extraordinary mastery on solar energy industry like Energia Solar Uruguay, ,Alternative EnergiesServices , Paneles Solares Uruguay ,Instalaciones Electricas Uruguay and more.
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