Glaring Study Solar Glint and Glare by Reflection of Solar Panels and other reflective surfaces
Glaring Study
Solar Glint and Glare by Reflection of Solar Panels and other reflective surfaces
Content
• Regulations
• Definition of Glaring
• Reflection on surfaces
• Examples of glaring
• Glaring calculation
• Glaring survey
• Glare-reducing measurements
Regulations
• FAA Technical Guidance for Evaluating Selected Solar Technologies on Airports(Form 7460)
§
Regulations - criteria
• Duration of the Glaring Hazard is the most important criteria
– maximum glare duration per day (e.g. 30 minutes)
– cumulated glare duration per year (e.g. 30 hours)
• Magnitude of the glare is less important, sun reflection almost always = disability glare
• Measurement / Simulation for single points of interest §
Definition of Glaring
• Disability GlareThe generally accepted metric for disability glare is the equivalent veiling luminance
• Discomfort GlareA nuisance measured on the deBoer‘s Scale
Reflection on Surfaces
reflecting surface
sun ray
Scattered light
Reflection
exit angle
angle of incidence
transmission & absorption
Examples
• Dazzling of highway traffic
• Dazzling of air traffic control towers
• Train driver not able to recognize a train signal
• neighbor disturbed by the glare of a large-scale PV plant
Solar Glare Calculation
• Duration during the year
• Duration during one day
• Angle to line of vision
• angle between sun and reflection
• size considerations
• distances and travel time considerations
Topography
Orientation of Surface in the space
Elevation
75 °
Azimuth
45 °
h1
6,0 m
h2
9,9 m
W
13,0 m L
4,0 m
© Zehndorfer Engineering Consulting e.U.Blend-Rechner V 3.2.2
Ground View (not to scale) Profile View (not to scale)
Calculation Model
Glare Occurrence
8:00
9:00
10:00
11:00 12:0013:00
14:00
15:00
16:00
5:00
6:00
7:00
8:00
9:00
10:00
11:0012:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
0
10
20
30
40
50
60
70
-120 -90 -60 -30 0 30 60 90 120
Sun
Ele
vati
on
[°]
Azimuth [°] (east = negative)
Glare Occurrence
Winter
Summer
Horizon
Scattering
Core Time
Blend-Rechner V 3.2.2
© Zehndorfer Engineering Consulting e.U.
Graph Copy 4
POI 1
PV A
Glaring days
Date H1 23.3.-21.6.
Date H2 21.6.-19.9.
Time 10:47-13:12
Zone UTC+1
Glare Duration
0
20
40
60
80
100
120
140
Jän Feb Mär Apr Mai Jun Jul Aug Sep Okt Nov Dez Jän
Min
ute
s p
er
day
Glare Duration [min]Blend-Rechner V 3.2.2 © Zehndorfer Engineering Consulting e.U.
POI 1
PV A
total scatter direct
per year 272 177 95 h
max/day 120 75 45 min
Line of Vision
-30
-20
-10
0
10
20
30
40
-40 -20 0 20 40 60 80
Cockpit View
sun
scatter
direct
PV
Blend-Rechner V 3.2.1
© Zehndorfer Engineering Consulting e.U.
POI 3
PV A
heading 135°
day 31.5.
time 16:17
distance 115m
Glare-Sun 45°
Glare-LOV 35°
Glaring Frequency
Solar Glare Assessment
• calibration of locations
– PV Plant
– Points of Interest
• Solar Glaring Calculation
– What if? Iterative Process
– Angle, Locations, Shading
• Interpretation and Evaluation
Glare-reducing measurements
• Change of the reflecting surface
• Shading of the reflecting surface
• Shading of the point of interest
• Change or orientation
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