36 – Part 4: Maintenance
Part 5: Specifications – 37
Part 5: Specifications
VELUX solar collector
VELUX collectors feature:
• Copper absorber plate coated with highly selective coating
having emissivity < 0.05 and absorptivity > 0.95
• Absorber coating applied by cathode sputtering process
• Collector flow tubes laser welded to the absorber plate
• Single layer cover glazing made of low iron tempered glass with
a direct solar transmittance > 0.89
• Back and sides of absorber plate insulated with rock wool,
maximum K-factor = 0.035 W/m K
• Extruded aluminum alloy 6063-T5 casing with 0.055” wall
thickness
Measurements (inches)
Width
Height
Depth
Code
U12
S06
M08
Code
U12
S06
M08
All
Gross
S
54.1
46.2
32.0
T
72.0
47.5
56.2
3.9
Frame
W
52.8
44.9
30.7
H
70.7
46.2
54.8
Glass
I
51.5
43.6
29.4
J
69.4
44.9
53.5
Aperture
E
49.5
41.6
27.4
F
67.4
42.9
51.6
Absorber
K
49.8
41.9
27.8
L
67.7
43.2
51.9
Technical specifications
CLR U12 4000
CLI U12 4000
CLI S06 4000
CLI M08 4000
Weight (lbs.)
Collector weight
130
130
73
57
Weight w/fluid
141
141
79
64
Collector area (sq. ft.)
Gross area
27.1
27.1
15.2
12.5
Aperture area
23.1
23.1
12.4
9.8
Absorber area
23.4
23.4
12.6
10.0
Fluid volume (gal.)
0.58
0.58
0.34
0.24
Max operating pressure (psi)
87
87
87
87
Test pressure (psi)
145
145
145
145
Stagnation temperature (°F)
374
374
374
365
Thermal performance rating - warm
climate (1000s btu/day)
Clear day
29
29
15
12
Mildly cloudy day
20
20
11
8
Cloudy day
11
11
6
5
Thermal performance rating - cool
climate (1000s btu/day)
Clear day
19
19
10
8
Mildly cloudy day
11
11
6
4
Cloudy day
4
4
2
1
Efficiency
eta0 (start efficiency)
0.6960
0.6960
0.6610
0.6390
a1 (Btu/hr*ft2*°F)
0.4747
0.4747
0.4666
0.4603
a2 (Btu/hr*ft2*°F2)
0.0020
0.0020
0.0019
0.0018
Structural performance
design pressure (DP)
Downward load (psf)
+70
+125
+200
+255
Uplift load (psf)
-60
-70
-87.5
-55
