Assessment of Photovoltaic Surface Texturing on ... · Assessment of Photovoltaic Surface Texturing...
Transcript of Assessment of Photovoltaic Surface Texturing on ... · Assessment of Photovoltaic Surface Texturing...
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia
Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of
Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
Assessment of Photovoltaic
Surface Texturing on
Transmittance Effects and
Glint/Glare Impacts (PowerEnergy2015-49481)
ASME 2015 Power and Energy Conversion Conference
San Diego, CA, June 28 – July 02, 2015
Julius Yellowhair
Clifford K. Ho
Sandia National Laboratories
Concentrating Solar
Technologies
Albuquerque, NM 87185-1127
SAND2015-5177C
Background
Motivation for this work
Approach
Results and Discussion
Conclusion & future work
Outline
2
Background – PV Module Construction
3
www.solarquotes.com.au
Background (2/2) – Reflections
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http://www.iala-aism.org/wiki/dictionary/index.php?title=Mixed_Reflection
1. Solar glint/glare from PV modules is caused by
reflections off PV glass covers – minimize this.
2. Maximizing transmittance through cover glass to
solar cells can increase energy production.
Motivation
5
www.pagerpower.com www.freerepublic.com
Surface Roughness Measurements Process
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Prepare & clean the PV panel to be replicated
Replicate the PV panel surface with a 2-part
rubber compound
Measure the small replica with
an optical profilometer
Analyze the measured surface data to get the
surface statistics
Mountain Digital Surf Matlab
1.
2.
3.
4.
Surface Roughness Measurement Data
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Reflectance Measurements
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Reflected Solar Beam Spread Measurements
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Smooth (float) glass, Lightly textured glass, Deeply textured glass
Samples courtesy of Canadian Solar, Inc.
Beam Spread Calculations
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0 0.2 0.4 0.6 0.8 1 1.2 1.40
200
400
600
800
x (m)Frame #212
500 1000 1500 2000 2500 3000 3500 4000
500
1000
1500
2000
2500
Beam spread at 1 = 27.3 mrad
00.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0
200
400
600
800
y (m
)
Beam spread at 1 = 27.8 mrad
Results on Surface Roughness & Beam Spread
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Ocular Hazards Study
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𝐸𝑟 =𝜌𝐸𝐷𝑁𝐼𝛽2
𝑑𝑝2𝜏
𝑓2
𝐸𝑟,𝑓𝑙𝑎𝑠ℎ =3.59 × 10−5
𝜔1.77
Irradiance on the retina:
Irradiance threshold for
after-image potential:
Ocular Impacts From PV Surface Texturing
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𝐸𝑟 < 𝐸𝑟,𝑓𝑙𝑎𝑠ℎ
𝛽 𝜌 >𝜌𝐸𝐷𝑁𝐼𝑑𝑝
2𝜏
𝑓23.59 × 10−5
10.23
Low potential
for after-image
Potential for
after-image
Low potential
for after-image
Potential for
after-image
Example of PV Cover Glass Design
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Measured reflectance, surface roughness, and solar beam spread from several PV modules
We attempted to correlate the beam spread to the surface roughness
Developed a design method to minimize glint/glare from PV modules and maximize transmittance
Results were incorporated in the SGHAT code
Would like to study soiling effects on textured surfaces
Build engineered surface texturing for PV and evaluate
Conclusions & Future Work
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Extra Slides
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Replication Accuracy & Verification
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Slope Error Calculation From Glare Measurements
• The angular beam spread after reflection is defined as:
– where the Sun subtended angle (𝜎Sun) is about 9 mrad
• The ‘Total Slope Error’ quantity is a combination of the panel surface slope error and specularity due to surface texturing; it’s typically defined as:
– where 𝜎SEis from the surface slope errors, and 𝜎Spis the specularity
from the surface texturing (i.e. surface roughness); the factor of 4 is because the surface slope errors are measured at the surface, whereas the specularity is measured at the reflected beam – note that with a single glare measurement, these two quantities are difficult to decouple
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𝜎BeamSpread = 𝜎Sun + 𝜎Total_SlopeError
𝜎Total_SlopeError = 4𝜎SE2 + 𝜎Sp
2
Note that can be one-sided or two-sided. In this analysis,
a two-sided is used, which gives the full beam spread.