9
GENERAL
Efficiency curve
0,75
0,80
0,65
0,70
0,55
0,60
0,45
0,50
0,40
0,35
0
0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08
Tm[m
2
K/W]
*
Description
U/M
Optical efficiency (
ηο
) (*)
0,784
-
Thermal dispersion factor (a1) (*)
4.08
W/(m
2
K)
Thermal dispersion temperature
dependence factor (a2) (*)
0,0084
W/
(m
2
K
2
)
IAM (50°) (*)
0,96
-
Efficiency (
ηcol
) (**)
61
%
(*)
Value referred to exposed area. Tested according to
EN 12975, referred to a 33.3% water-glycol mix, flow
rate of 160 l/h, and irradiation G = 800W/m
2
.
Tm = (Coll._inlet _temp.+Coll._outlet_temp.)/2
T*m =
(Tm-T_ambient)/G
(**)
Calculated with a temperature difference of 40K
between the solar collector and the surrounding air,
and with total solar radiation of 1000 W/m
2
referred to
the exposed area.
WIND AND SNOW LOADS ON COLLECTORS
Installation
height above
ground
Wind speed
Mass in kg to secure collector
against lifting by wind
Load on roof from wind, snow, and
collector weight
At angle of
45
°
At angle of
20
°
At angle of
45
°
At angle of
20
°
0 - 8 m
100 km/h
80 kg
40 kg
320 kg
345 kg
8 - 20 m
130 km/h
180 kg
90 kg
470 kg
430 kg
20 - 100 m
150 km/h
280 kg
150 kg
624 kg
525 kg
Maximum permitted load from wind and snow (including combined loads) on surface of collector: 1500 Pa (175
km/h).
Pressure drop in solar collectors (*)
30
25
20
15
10
5
0
0
50
100
150
200
250
300
350
Pressure drop (mbar)
Flow rate (l/h)
(*) With antifreeze-water mix of 33,3% / 66,7% and heat transfer medium temperature = 20°C.
