Measurement of total and spectral solar irradiance: Overview of existing research

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  • Renewable and Sustainable Energy Reviews 15 (2011) 14031426

    Contents lists available at ScienceDirect

    Renewable and Sustainable Energy Reviews

    journa l homepage: www.e lsev ier .co

    Measu nc

    Yousef A hma Physics Depab Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

    a r t i c l

    Article history:Received 19 MAccepted 26 OAvailable onlin

    Keywords:SolarTerrestrialExtraterrestriaSpectrumBroadbandVisibleUVNear IR

    Contents

    1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14032. Measu

    2.1.2.2.

    3. Measu3.1.

    3.2.

    4. Extrat5. Concl

    Refer

    1. Introdu

    The inteof the radiasity and wa

    CorresponE-mail add

    1364-0321/$ doi:10.1016/j.ring broadband solar irradiance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1404Total broadband solar irradiance measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1404Ultraviolet broadband solar irradiance measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1406ring spectral global solar irradiance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1707Visible and near-infrared. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14073.1.1. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14073.1.2. Detection system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1407Ultraviolet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14183.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14183.2.2. Detection systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14183.2.3. Measurements of spectral solar UV irradiance in the tropic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14193.2.4. Measurements of spectral solar UV irradiance outside the tropic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1420

    erresterial solar radiation measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1422usions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1425ences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1425

    ction

    nsity of solar radiation varies with the wavelengthtion, and the functional relationship between inten-velength is called the solar spectral distribution. The

    ding author.ress: y.a.eltbaakh@gmail.com (Y.A. Eltbaakh).

    spectral distribution of solar radiation outside the earths atmo-sphere, called the extraterrestrial or airmass zero (AMO) spectrum,is well characterized. It roughly resembles the spectrum of a black-body at 5900K (Hulstron [1]) with a peak of the spectrum at awavelength of about 500nm (Webster [2]) and the exception ofabsorption lines caused by attenuation of radiation in the mediumsurrounding the sun (Hulstron [1]). This distribution is very impor-tant in solar applications such as the photovoltaic power systemsof satellites, because their performances are spectrally dependent.

    see front matter 2010 Elsevier Ltd. All rights reserved.rser.2010.10.018e i n f o

    ay 2010ctober 2010e 12 January 2011

    l

    a b s t r a c t

    The quantitative assessments of the solar radiation ux and the variations of its spectral distribution inthe visible and near-infrared ranges of the electromagnetic spectrum are of great interest in studyingsolarterrestrial inuences. The reason is that the main part of the solar radiation energy is concentratedin that range and it determines the thermal equilibriumof the earths atmosphere. This paper provides anoverview of spectral global solar irradiance observations and of broadband solar irradiance observationsfrom the ultraviolet to the near infrared. Measurements of the spectral solar irradiance in the near UV,visible and near IR were carried out by many researchers in two types of measurements; spectral globalsolar irradiance and broadband solar irradiance. The results from this study show that the measurementof the spectral solar radiation in the near UV, visible and near IR ranges can be made either by highprecision and expensive instruments or by aid of rather simple, less precise and comparatively inexpen-sive broadband instrumentpyrheliometers or pyranometers in combination with glass lters. Selectednarrow waveband instruments are characterized by simpler, less expensive and easy to maintain andcalibrate compared to high-resolution scanning instruments.

    2010 Elsevier Ltd. All rights reserved.m/locate / rser

    e: Overview of existing research

    anb, K. Sopianb, M.I. Fadhelbrement of total and spectral solar irradia

    . Eltbaakha,, M.H. Ruslanb, M.A. Alghoulb, M.Y. Otrtment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

  • 1404 Y.A. Eltbaakh et al. / Renewable and Sustainable Energy Reviews 15 (2011) 14031426

    A knowledge of this distribution provides a design input for thebetter thermal environment of a spacecraft and for the selection ofsuitable materials exposed to solar radiation (Igbal [3]). When thissolar radiation passes through the earths atmosphere, the spec-tral distriburadiation bywater-vapoat any timelength of somass dependay, and da

    The elecing the earspectral, orrangeofwaspectral orspecic unidenoted byirradiance amatic globaor mWm2

    to a narrow(for examplspectral systor responsit possible tdetector mindirectly, ithe presenteffort; rstsolar irradiis interestedthe same rethat used to

    2. Measuri

    Broadba(irradiance)uniformly sshort wave(Calisesi etsure solar ror the photusing thermwhich cons(Ghassemi [neous respodevices, pheld of solaof a semiconused tomeasphere fall t

    1. Pyrheliomation. Inradiationsuns diskplaced atthe anguThe instrthe sun i

    2. Pyranomdiffuse raradiation

    onth

    radildedile wunhbe e

    tact wlacing the junctions in contact with a black surface (withthermal conductivity) or by placing a black coating on thetions. The instrument is installed in a level position, the sen-acing up towards the sky. Less expensive pyranometersmaya photovoltaic sensor to measure solar radiation (Pecht [5]).

    tal broadband solar irradiance measurement

    and Li [8] measured both hourly horizontal global and dif-lar components at City Polytechnic of Hong Kong duringear period from 1991 to 1993 by using two pyranometers), manufactured by Kipp and Zonen. The diffuse radiationmeter was tted with shadow-ring (CM121) to shade thepile from the direct sun. The pyranometers connected togrator (CM12) to calculate radiation over selected periods.al program had been written to capture the data from thetor and store the data on a micro-computer. The monthlye of daily global, diffuse and direct solar radiations on a hor-l surface are shown in Fig. 1. The results showed that thel average of global, diffuse and direct radiation were 13.4,6.6MJm2 d1 respectively. Solar radiation during the day

    o bemore evenly distribution in summer than inwinter, andximum hourly value occurred at solar noon for both globalffuse radiation.vides et al. [9] used several measured wavebands,

    30nm, 300710nm and 3002800nm which was measuredhe LinkeFeussner pyrheliometric in Athens, Greece for the19541990 to study the effects of aerosol on the directtion is modied by absorption and scattering of theatmospheric constituents, such as aerosols, ozone, andr. The exact spectral distribution at the earths surfacedepends on local atmospheric conditions and the pathlar radiation through the atmosphere (or air mass). Airds on the sun angle, which varies with location, time ofy of year (Hulstron [1]).tromagnetic radiation coming from the sun and reach-ths surface can be measured as broadband or total,monochromatic. Totalmeasurements include thewholevelengthsor thewholeof correspondingenergies,whilemonochromatic measurements are associated with at of wavelength. Total global irradiance which can beH and whose unit is Wm2 is the solar hemisphericrriving at any point on the earths surface. Monochro-l irradiance is denoted by H, its units are Wm2mnm, and it is the hemispheric irradiance correspondingband of wavelength, as narrow as possibly measurablee: 1nm, 0.5nm, 0.1nm, etc.). In general, both solar andtems consist of a receiver, a detector, a signal or detec-e processor and a counting system. The receiver makeso receive radiation and to transfer it to the detector. Theakes it possible to convert the solar energy, directly orntoanelectrical signal (Pinedoet al. [4]). Theobjectiveofstudy can be broadly classied into threefold researcheffort is concerned with the measuring spectral globalance from the ultraviolet to the near infrared. Second,in the measuring broadband global solar irradiance at

    gion of wavelengths. The last one covers the methodsmeasure the extraterrestrial solar radiation.

    ng broadband solar irradiance

    nd instruments measure the combined solar intensityat all wavelengths (Pecht [5]). The instrument must beensitive to all wavelengths from the very energetic andlength X-rays to the very longest infrared wavelengthal. [6]). The most commonly used instruments to mea-adiation today are based on either the thermoelectricoelectric effects. The thermoelectric effect is achievedopile that comprises collections of thermo couples,

    ist of dissimilar metals mechanically joined together7]). The photoelectric effect is simpler andhas instanta-nse and good overall stability. Among the photoelectricotovoltaic instruments (PV) are most numerous in ther radiationmeasurement. A photovoltaic device ismadeductingmaterial such as silicon (Igbal [3]). Instrumentssure the transmission of sunlight through earths atmo-wo general categories (Ghassemi [7]):

    eters: these are instruments that measure direct radi-struments measuring direct radiation usually includecoming out to an angle of about 3 away from the. The sensor is a temperature-compensated thermopilethe bottom of a blackened collimator tube that limitslar acceptance of solar radiation to about 56 (total).ument is oriented such that the direct radiation froms parallel to the axis of the collimator tube.eters: these are instruments that measure global anddiation. Theyhave a shadingdisk to prevent direct solarfrom reaching the sensor. The measurement for dif-

    Fig. 1. MLi [8]).

    fuseshiemopThemayconby phighjuncsor fuse

    2.1. To

    Lamfuse sothe 3-y(CM11pyranothermoan inteA Pascintegraaveragizontaannua6.8 andlends tthe maand di

    Jaco3006using tperiodly average of daily global, diffuse and direct solar radiation (Lam and

    ation involves correcting for the portion of the radiationfromthe sensorby the shadingdisk. The sensor is a ther-ith alternate blackened junctions heated by the sun.

    eated junctions are near ambient temperature, whichnsured by putting the unheated junctions in thermalith a white surface, heating by the sun is accomplished

  • Y.A. Eltbaakh et al. / Renewable and Sustainable Energy Reviews 15 (2011) 14031426 1405

    beamspectral solar irradiancedistribution througheffectiveopticaldepths. The observationsweremade at theNational Observatory ofAthens (NOA: latitude=3758, longitude=2343E, height abovesea level = 107m), at 11:20 and 14:20, Local Standard Time (LSTis 2h ahead of UTC) were used whenever clouds did not obscurethe sun. Approximately seven thousand observations of directsolar spectra (300710nm) were taken under clear sky conditionsdened to be less than 1/8 cloud cover with no clouds near thesun disk. Effective optical depths in the wavebands 300630nm,300710nm and 3002800nm were calculated using Eqs. (1)(3)respectively

    t =[ln It ln It]

    m(1)

    where It = I and It = I are the direct beam irradiances for anaerosol free and a real atmosphere, respectively, for the wholespectrum 3002800nm.

    t = [ln Ir ln Ir]m

    (2)

    where Ir = I(300630nm) and Ir = I(300630nm) are the correspondingdirect beam irradiances for the nite waveband 300630nm.

    v = [ln Iv ln Iv]m

    (3)

    where Iv = I(300710nm) and Iv = I(300710nm) are the correspondingdirect beam irradiances for the nite waveband.

    Fig. 2 shoptical depthe Athens

    1 The relatibe linear.

    2 Both spec1954 untually. tand fromDuring thmean mocoincide.

    3 The resuldirect beaby atmosdirect irra

    Fig. 2. Monthldard deviation

    altered as attenuation by scattering increases markedly towardsshorter.

    4 Theeffectof increasingaerosol concentrationson thevisiblebandin the direct solar beam was investigated indirectly through thespectrally resolved optical depth v. It was shown that the directsolar beamin thewaveband300700nmwasmarkedlydepleted.

    Singh et al. [10] measured the global solar radiation on a hor-izontal surface at Lucknow (latitude 26.75N, longitude: 80.50E,altitude120mabovesea level),UttarPradesh...