IIT Bombay DESE Solar Geometry Lecture 8 04082011

IIT Bombay DESE Solar Geometry Lecture #8 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 1

Angle betwn tilted surface & sun ray IIT Bombay DESE Azimuth angle (g) is given by 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 2

IIT Bombay DESE Zenith angle(qz) is given by Sunrise and sunset hour angle is given by Time difference between noon sunrise or sunset (hour) 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 3

Sun path in cylindrical coordinate 04/08/2011 EN 601: Lecture 7: Solar Geometry IIT Bombay DESE Slide 4

Sun path in polar coordinate 04/08/2011 EN 601: Lecture 7: Solar Geometry IIT Bombay DESE Slide 5

IIT Bombay DESE Day length (hour) Solar time: Time corresponding to the position of sun i. e. , based on hour angle w Standard time: Time corresponding to the position of sun at a reference place known as standard longitude for a country ystd. At standard longitude: Solar time=Standard time + equation of time (Et) 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 6

IIT Bombay Equation of time Celestial equator DESE Normal to the orbit North Celestial pole Orbital tilt Elliptical plane 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 7

IIT Bombay DESE Equation of time The equation of time results mainly from two different superposed astronomical causes each causing a different non-uniformity in the apparent daily motion of the Sun relative to the stars, and contributing a part of the effect: the obliquity of the ecliptic (the plane of the Earth's annual orbital motion around the Sun), which is inclined by about 23. 44 degrees relative to the plane of the Earth's equator; and the eccentricity and elliptical form of the Earth's orbit around the Sun. 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 8

Local Standard Time (LST) IIT Bombay DESE Sunrise & sunset time 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 9

Sun path in polar coordinate IIT Bombay DESE 20 degree 40 degree 04/08/2011 EN 601: Lecture 7: Solar Geometry E Slide 10

Sun path in polar coordinate IIT Bombay DESE 20 degree 40 degree 04/08/2011 EN 601: Lecture 7: Solar Geometry E Slide 11

Sun path in polar coordinate IIT Bombay DESE 20 degree 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 12

Sun path in polar coordinate IIT Bombay DESE 20 degree 40 degree 04/08/2011 EN 601: Lecture 7: Solar Geometry E Slide 13

Solar radiation on horizontal surface IIT Bombay DESE f f 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 14

Solar radiation on horizontal surface IIT Bombay DESE d d f-d f f f d f+d f d Zenith angle at solar noon : f - d 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 15

IIT Bombay Assignments DESE #4: Calculate the date and time when the air mass at Mumbai (Latitude : 18 o. N, Longitude: 72 o. E) is maximum solar radiation. Given, Std. Longitude for India: 82. 5 o. E. #5: You plan to install a solar energy converter on the equator. There is a hill (180 m high and 0. 95 km wide) on the east side at a distance 1 km from the site of the installation. Estimate the energy loss in percent due to obstruction Write down the assumption adopted for estimation 04/08/2011 EN 601: Lecture 7: Solar Geometry Slide 16