02_Solar_radiation09

02_Solar_radiation09 - Solar Radiation ELEG620 Solar...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Solar Radiation
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Solar Radiation •O u t l i n e – Properties of radiation: Summary of equations, terms, concepts – Solar Spectra – Terrestrial Solar Radiation: Effects of atmosphere, angular dependence of radiation, variation of solar radiation – Calculation of Solar Radiation: • Estimate of intensity of solar radiation • Angular Dependence – Solar Noon calculations – Time-based calculations – Solar Radiation Data Sets – Radiation hitting a panel Caution: Watch out for units!!! Make sure you pay attention to radians, degrees. Also pay attention to “details” - which hemisphere, difference between solar noon and local time, etc.
Background image of page 2
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Solar Radiation •G o a l s – Calculate power density, photon flux, photon energy, photon wavelength & relationships between them. – Calculate properties of arbitrary light source given its spectral irradiance – Calculate properties of black body radiation: power density, peak emission wavelength. – Convert local time to solar time – Determine angles of incident sunlight, both at solar noon and as a function of time. – Determine light normal to a surface, at solar noon and at an arbitrary time
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Photovoltaic Effect • First observed in 1839! (Becquerel) • Seen when some combinations of different materials are exposed to light – we see a current flow • Current is extracted with a potential difference due to different materials – hence it is a ‘voltaic’ effect
Background image of page 4
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Nature of light • Light acts as both wave and particle – basis of quantum theory • Einstein (1905) explanation of the photoelectric effect calls for quantized particles of light - photons • Energy of photon determined by the wavelength or frequency (they are equivalent) of the light h υ = Φ + ½mv 2 h is Planck’s constant Φ is work function υ is frequency of light v m is maximum velocity of ejected electron m Only get emission when h υ > Φ
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Properties of Radiation Summary of equations & concepts: Wave/energy relationship: Common units of energy: electron-V (eV) 1 eV = 1.602x10 -19 J Power density (H, W/m²) and monochromatic photon flux ( Φ , photons/sec·m²): Power density (in W/m²) is photon flux (# photons/m²·sec) multiplied by energy per photon. () m q J hc m W H µ λ 24 . 1 ) ( 2 Φ = × Φ = Burn into brain!
Background image of page 6
ELEG620: Solar Electric Systems University of Delaware, ECE Spring 2009 S. Bremner Paint me a spectrum Rarely have single wavelength, more usual to have a spectrum Sun provides a spectrum of light – we need to know how to handle this Need some way of conveying the spectra in a sensible format Spectral irradiance, F, is standard way to specify the properties of a light source Gives the power density at a particular wavelength.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/14/2011 for the course ELEG 620 taught by Professor Honsberg,c during the Fall '08 term at University of Delaware.

Page1 / 54

02_Solar_radiation09 - Solar Radiation ELEG620 Solar...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online