Calculation of the position of the sun in the sky for each place on earth at any time of the day. solar path graphs. dawn and sunset are defined as the time when the top of the solar disk touches the horizon. this corresponds to an elevation of -0.833 ° degrees for the sun. twilight is the moment immediately after sunset; characterized by a diffuse light (by extension; during the morning one speaks of dawn or dawn). civil twilight is the time interval during sunset and when the sun elevation is -6 °. a few very bright stars and planets are visible in the sky. nautical twilight> represents the time when the sun passes from -6 ° to -12 ° below the horizon; in this period the horizon and the main stars are distinguished. astronomical twilight is the time interval during sunset when the elevation of the sun is -18 ° below the horizon. the sky is dark and stars above the sixth magnitude can be distinguished. noon in solar time occurs when the sun reaches the highest point in the sky; to the south or north depending on the latitude of the observer. azimuth indicates an angle between a point and a reference plane. generally it is the angular distance of a point from the north; measured in degrees: 0 ° north; 90 ° east; 180 ° south; and 270 ° west. the height or elevation; is the angular distance from the horizon of a point on the celestial sphere; calculated as positive if located towards the zenith; or negative if it is situated towards the nádir. the zenith; is the intersection of the perpendicular to the plane of the horizon that passes through the observer with the visible celestial hemisphere; and therefore it is the point above the head of the observer. the diametrically opposite point is the nádir. knowledge of position and daylight hours; allow us to know the energy radiated by the sun (renewable source) at the point of the earth that we are examining. solar energy can be thermal produced by thermal solar panels or electrical produced by photovoltaic panels.