The peak solar time that is received in a given area at a given instant is known as irradiance and is measured in units of W/m2. In integration of the irradiance at a given time period is known as heat stroke and its units are KWh/m2, KJ/m2, BTU/ft2. Heat stroke can also be expressed in terms of peak solar hours. The peak solar hours is equivalent to the energy received during one hour at an average irradiation of 1000 W/m2. Sun-Earth relative motions of solar energy facilities need the sun to work, therefore, is important to know how this interacts with the earth so that we can describe their behavior and trajectory in the sky and achieve with this knowledge in accurately the performance of the facility we are proposing for over a year as the seasons change and with them the weather of the place, also the path of the sun in the sky and the energy we receive from him . Translation movement: This movement is what makes the earth spinning around the sun It does describe an elliptical orbit, which is called Ecliptic. The journey is 365 days 5 hours and 48 minutes at a speed of 108.000 km / h or so.
Rotational movement: This movement is what makes the earth around its axis, ie on the line connecting the north and south poles, the shaft maintains a nearly constant direction and an angle of 23.45 degrees to the plane of the obliquity of the ecliptic called the ecliptic. Because of this obliquity the angle formed by the earth's equatorial plane with the line joining the centers of the earth and the sun, the earth is constantly changing between more and less than 23.45 degrees 23.45 degrees. This angle is called the solar declination and day length dependent at different times of the year, giving rise to the phenomenon of the seasons. To understand this phenomenon, see the following figure, which shows the position of the land in winter and summer solstices. As we can see, the northern hemisphere has much more sun time in June than in December, and the sun illuminates a wider area in the hemisphere. The opposite happens in the southern hemisphere. Equinoxes and Solstices The equinoxes are the times of the year, where day length is equal to the night, the autumnal equinox occurs on September 21 and the spring on March 21, both set the commencement of such stations.
The longest day and shortest of the year are called solstices and occur respectively on 21 June and 21 December. Also set the start of summer and winter seasons. So the seasons are the periods delimited by the two equinoxes, the solstices and the position of the earth to the sun. Coordinates Solar solar coordinates are used to determine the position of the sun referred to the horizontal plane are two and are defined as follows: H Solar (h): The angle between the sun's rays on a horizontal surface. The increase in height is called the solar zenith angle or zenith distance. Solar azimuth (A): The angle half rotation of the sun on the horizontal plane by projecting the ray on the plane and taking as origin the south.