PV BASIC PART 1 ITECH 2012-Dr. O.S. SASTRYDIRECTOR, PV TESTINGSOLAR ENERGY CENTRE

SPV BASICS- PART Dr O.S SASTRY DIRECTOR, PV TESTING SOLAR ENERGY CENTRE PH 0124-2579213; Fax: 0124-2579207e.mail: sastry284 @yahoo.in Energy Determines the Quality of Life Resource Estimation is Very Important We study about the Solar radiation Resource LECTURE FORMAT • Understanding SUN • SUN Spectrum • AIR MASS ( AM x) • How to Measure Radiation ? • Solar Radiation Mapping • How to Obtain Ground Data ? • How to Obtain Satellite Data ? UNDERSTANDING SUN The SUN Source of all Energy Produces Energy from H2 4H1 →He4 + 2β + + 2ν + 25 MeV E = mc2 The Solar Constant • The geometry of the sun - earth relationship is schematically shown in the figure • The eccentricity of the earth’s orbit is such that the distance between the sun and earth (1.495 × 1011m) varies by 1.7 per cent • The sun sub-stends an angle of 32' at the earth because of its large size and distance • The radiation emitted by the sun reaches un-attenuated up to the outside of the atmosphere and thus is a fixed intensity • The solar constant (Ion) is the energy received from the sun, per unit time, on a unit area of surface perpendicular to the direction of radiation, at a mean earth-sun distance, outside the earth atmosphere • The latest value of solar constant is 1366.8 ± 4.2 watts/m2 or 433 Btu/f2 hr or 4.921 MJ/m2 hr or 1.960 cal/cm2 ATMOSPHERIC EFFECTS On incoming radiation: Solar radiation having wavelength less than 0.29µ(UV) is absorbed in ozone layer Thus the atmosphere cuts off most of the ultraviolet part of solar radiation The solar radiation, that traverse the atmosphere downward, is further subjected to depletion by scattering and reflection by air molecules, aerosols and clouds The infrared portion of the solar radiation, which traverses the atmosphere downward, also suffers depletion by selective absorption at various wavelengths by O2, water vapor, and other components including Co2 On outgoing radiation: The long wave radiation (4µ - 120 µ), that is emitted upward by the earth, also suffers selective absorption by water vapor and Co2, which leads to heating of the atmospheric layers The atmosphere is transparent for 8µ - 12µ and most of the terrestrial radiation escapes into space through this window Global Radiation Budget RADIATION BUDGET Incoming: Backscattered to space by Air Reflected by clouds Absorbed by atmosphere and clouds Reflected by earth’s land-sea surface Absorbed by earth Outgoing: Heat transported upward by convection and turbulence Heat transported upward through evaporation Net loss of energy in the form of long wave radiation ( 4µ to 120µ with the peak at 10µ ) Percentage of total : : 21 : 21 : : 48 : 10 : 22 : 16 UNDERSTANDING AIR MASS (AM X) The distance travelled by the sunbeam in the earth’s atmosphere is responsible for the amount of scattering, absorption and reflection of solar radiation The shortest distance travelled by the sunbeam in the atmosphere is when the sun is at the Zenith and is longest when the sun is rising or setting Airmass ‘m’ is defined as : actual path length travelled AB m= = vertical depth of the atmosphere AC = cosec α = Sec φ Z m = when outside the earth atmosphere m = when sun is at the Zenith m = when Zenith angle is 60° Most African, Latin American countries and India are in the solar belt of the world, A potential for utilizing solar energy RADIATION MEASUREMENTS COMPONENTS OF SOLAR RADIATION Sunlight that reaches the earth’s surface has two components: Direct or beam radiation Diffuse radiation The portion of radiation that has been scattered or refracted Global Radiation The sum of Direct and Diffused that actually Reaches the surface of module RADIATION MEASUREMENTS S.NO PARAMETER Short Wave (0.3µ - 4.0 µ): Direct (S) Global (S.cosθ+D) θ – Zenith angle Diffuse (D) INSTRUMENTS USED Ångström and Thermoelectric Pyrheliometers Thermoelectric Pyranometer Thermoelectric Pyranometer with shading ring Inverted Pyranometer Sunphotometer Reflected Solar spectral irradiance and turbidity Long Wave(4µ - 100 µ): Net Terrestrial Ångström Pyrgeometer Radiation Total(0.3µ - 100 µ),: Upward or downward Pyradiometer Radiation Net Radiation Net Pyradiometer MONITORING OF WEATHER DATA AT SEC Indian solar Radiation Data Base HISTORY Derived Radiation data for 145 Stations in India The network of 145 stations covers all major climatic zones In the country Total 482 tables Contains Global, diffuse and direct solar radiation on horizontal and tilted surfaces Other meteorological parameters Also includes : •Extraterrestrial solar radiation •Number of clear sky days •Clearness index •Precipitable water •Surface pressure Revised & Updated Handbook of Solar Radiation Project undertaken by Solar Energy Centre with IMD • Increasing applications of solar technologies require more accurate data • New meteorological stations added in Indian network • More in-depth analysis • Analysis being carried out on recent data collected during 1986-2000 • Data being presented in a format suitable to carry out computer based design optimization studies The draf revised handbook expected in December 2006 Solar Resource Assessment India lies in the solar belt of the world A potential region for utilizing solar energy Information of solar radiation as available on the ground surface • Quantity • Spatial distribution • Temporal characteristics NREL- SEC India Solar Resource Maps (2010) END PART-I THANK YOU !! [...]... (0.3µ - 4.0 µ): 1 Direct (S) 2 3 4 5 Global (S.cosθ+D) θ – Zenith angle Diffuse (D) INSTRUMENTS USED Ångström and Thermoelectric Pyrheliometers Thermoelectric Pyranometer Thermoelectric Pyranometer with shading ring Inverted Pyranometer Sunphotometer Reflected Solar spectral irradiance and turbidity Long Wave(4µ - 10 0 µ): 1 Net Terrestrial Ångström Pyrgeometer Radiation Total(0.3µ - 10 0 µ),: 1 Upward or... How Solar Energy is Generated? And Its Components • Originates with the thermonuclear fusion reactions occurring in the sun • The sun is, in effect, a continuous fusion reactor • The fusion reaction in which hydrogen (i.e four protons) combines to form helium (i.e one helium nucleus) accompanied by a 0.7 percent loss of mass and converted to energy is the source of energy in the SUN Solar Energy Consists... • Process of energy transportation between two points without the help of any medium • Such energy is also termed as radiation • Radiation energy is in the form of electromagnetic waves either of single wavelength (monochromatic) or may occupy a band of wavelength (spectrum) • Various spectra of electromagnetic waves are known by different name depending upon their uses and wavelength 1 Radio Waves... Basic Earth – Sun Angles • For calculating solar radiation and designing solar devices, the knowledge of sun’s path in the sky, on various days in a year at a particular place is a pre-requisite • Solar altitude angle (α) and solar azimuth angle (Az) are the two coordinates locating the sun in the sky • The apparent solar path on a particular day is shown in the figure... pressure Revised & Updated Handbook of Solar Radiation Project undertaken by Solar Energy Centre with IMD • Increasing applications of solar technologies require more accurate data • New meteorological stations added in Indian network • More in-depth analysis • Analysis being carried out on recent data collected during 19 86-2000 • Data being presented in a format suitable to carry out computer based... 2006 Solar Resource Assessment India lies in the solar belt of the world A potential region for utilizing solar energy Information of solar radiation as available on the ground surface • Quantity • Spatial distribution • Temporal characteristics NREL- SEC India Solar Resource Maps (2 010 ) END PART- I THANK YOU !! ... µ),: 1 Upward or downward Pyradiometer Radiation 2 Net Radiation Net Pyradiometer MONITORING OF WEATHER DATA AT SEC Indian solar Radiation Data Base HISTORY Derived Radiation data for 14 5 Stations in India The network of 14 5 stations covers all major climatic zones In the country Total 482 tables Contains Global, diffuse and direct solar radiation on horizontal and tilted surfaces Other meteorological... travelled AB m= = vertical depth of the atmosphere AC = cosec α = Sec φ Z m = 0 when outside the earth atmosphere m = 1 when sun is at the Zenith m = 2 when Zenith angle is 60° Most African, Latin American countries and India are in the solar belt of the world, A potential for utilizing solar energy RADIATION MEASUREMENTS COMPONENTS OF SOLAR RADIATION Sunlight that reaches the earth’s surface has two components:... at approximately 6000K • The spectrum ranges from a fraction of a nm to hundreds of meter • The region between 250 nm to 3000 nm carries 98% of the total emitted energy • The visible spectrum region from 400 nm to 770 nm carries 50% of its energy with maxima around 550 nm UNDERSTANDING AIR MASS (AM X) The distance travelled by the sunbeam in the earth’s atmosphere is responsible for the amount of scattering,... the two coordinates locating the sun in the sky • The apparent solar path on a particular day is shown in the figure thereby showing sun’s zenith angle (θ z), altitude (α) and azimuth angle (Az) at a particular position of the sun • The altitude angle of the sun (α) is defined as the angle in a vertical plane between the sun’s rays and the horizontal projection of the sun rays • The azimuth angle (Az) ... loss of energy in the form of long wave radiation ( 4µ to 12 0µ with the peak at 10 µ ) Percentage of total : : 21 : 21 : : 48 : 10 : 22 : 16 Basic Earth – Sun Angles • For calculating solar radiation... eccentricity of the earth’s orbit is such that the distance between the sun and earth (1. 495 × 10 11m) varies by 1. 7 per cent • The sun sub-stends an angle of 32' at the earth because of its large... outside the earth atmosphere • The latest value of solar constant is 13 66.8 ± 4.2 watts/m2 or 433 Btu/f2 hr or 4.9 21 MJ/m2 hr or 1. 960 cal/cm2 ATMOSPHERIC EFFECTS On incoming radiation: Solar radiation