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Replicated: D. C. Beekley and G. R. Mather, Jr., “Analysis and experimental tests of a high-performance evacuated tubular collector,” DOE/NASA CR-150874, 1978. Manuscript Freely obtained at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008199_1979008199.pdf

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http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008199_1979008199.pdf

Latitude = 40° Tilt = 28°

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http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008199_1979008199.pdf

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!.18)'$%@*An*P.&D#/*A.^/'*First glance: cylindrical tube panel (Solyndra) performs better than flat panel (Solar Frontier) Second glance: we need to normalize for differences in solar cell active area Third glance: there is the characteristic kink in the curve due to critical angle phenomenon

Elec

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3 September 2012 Latitude = 37.3492°

Longitude = -121.9381° Altitude = 20 m

White-Panel Backplane

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First glance: flat panel (Solar Frontier) performs better than cylindrical tube panel (Solyndra) Second glance: we are gaining some power from the open regions in the panel, but not doubling Third glance: the kink is still there due to critical angle phenomenon

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al

3 September 2012 Latitude = 37.3492°

Longitude = -121.9381° Altitude = 20 m

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28 October 2012 (AM1.5 Conditions) Latitude = 37.3492°

Longitude = -121.9381° Altitude = 20 m

Black Velvet Backplane

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9/2/12 7:12 PM 9/3/12 12:00 AM 9/3/12 4:48 AM 9/3/12 9:36 AM 9/3/12 2:24 PM 9/3/12 7:12 PM 9/4/12 12:00 AM

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Site data and time infolatitude in decimal degrees (positive in northern hemisphere) !"#!$%&longitude in decimal degrees (negative for western hemisphere) '(&(#%!)(ground surface elevation (m) 20.0time zone in hours relative to GMT/UTC (PST= -8, MST= -7, CST= -6, EST= -5) -8daylight savings time (no= 0, yes= 1) 1start date to calculate solar position and radiation 3-Sep-12start time 12:30 AMtime step (hours) 0.5number of days to calculate solar position and radiation 1Bird model parametersbarometric pressure (mb, sea level = 1013) 1013ozone thickness of atmosphere (cm, typical 0.05 to 0.4 cm) 0.225water vapor thickness of atmosphere (cm, typical 0.01 to 6.5 cm) 2aerosol optical depth at 500 nm (typical 0.02 to 0.5) 0.26aerosol optical depth at 380 nm (typical 0.1 to 0.5) 0.3forward scattering of incoming radiation (typical 0.85) 0.85surface albedo (typical 0.2 for land, 0.25 for vegetation, 0.9 for snow) 0.2Bras model parameterBras atmospheric turbidity factor (2=clear, 5=smoggy, default = 2) 2Ryan-Stolzenbach model parameterRyan-Stolzenbach atmospheric transmission factor (0.70-0.91, default 0.8) 0.8

Calculation of solar position based on NOAA's functions and clear-sky solar radiation based on Bird and Hulstrom's model, Bras model, and Ryan and Stolzenbach's model.

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Solar Spectrum = AM1.5 CIGS QE = NREL literature 3 September 2012 Latitude = 37.3492° Longitude = -121.9381° Altitude = 20 m White-Panel Backplane

Solar noon results only shown on central tube

Pe,tube (tracing) = 2.53 W

Pe,array = 101.2 W

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experiment

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Comparison of Solyndra cylindrical tube panel: experiment and ray trace model – good agreement. Variations due to solar source assumptions, such as atmospheric conditions Indicates that software ray-tracing model validates virtual design method. El

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3 September 2012 Latitude = 37.3492°

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