EverHot 1000/BL1, Technical Manual

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Efficiency curves of MEGASUN solar collectors
ST 2000 Selective (2,10m 2
, 24 C)
ST 2500 Selective SUN-POWER Selective
a. Test Nr: 1021 b. Test Nr: 30.0012.0-3 c. Test Nr 28601068
• Curve a:
Test by DEMOKRITOS (Greece) n= 0,85 - 5,44 T*
• Curve b:
Test by CENER (Spain) n= 0,767-0,37 (tm - ta)/G
• Curve c:
Test by TÜV Bayern (Germany) n=0,794-3.907 T*- 0,0157 (

m-

L)T*
• Curve d:
Calculus CST Bat (France) y = -4,8648x + 0,7063
d. Avis Technique 14/05-947
Procedure for the calculation of estimated energy output of collector
The collector instantaneous efficiency curve is expressed by the following relation in linear or second-order form:
where n is the collector instantaneous efficiency, Tm is the mean temperature of water inside the collector, in ºC, Ta is the
ambient air temperature, in ºC and G is the total solar radiation that falls in the collector, in W/m2. The parameters of the
above equations of the instantaneous efficiency curve n0 and U0 are determined by testing according to the standards EN
12975-2 and ISO 9806-1.
The estimated energy output of the collector is calculated using the values of parameters n0 and U0, as these have been
Determined by testing from several accredited laboratories of Europe, for a number of cities and under the following conditions:
- solar radiation, ambient air temperature and temperature of cold water (average monthly values as given in the tables of
the following page)
- Temperature of hot water delivered by the collector to the user equal to 45ºC and 40ºC.
For every day of the month the efficiency of the collector is calculated, where the maximum efficiency and the heat losses of
the collector are taken into account depending on the existing climatic conditions of the day and the desired temperature of
hot water delivered by the collector to the user. Also, the latitude of the area of installation and the slope of the collector are
taken into account. Following this, the mean monthly output of the collector is calculated using the climatic data of the month.
Finally, the sum of the mean monthly outputs of the collector gives the total annual output. It is noted that the values of the
estimated energy output of the collector that are calculated and given in the next tables are the maximum estimated and
therefore they are achieved only by the optimum design and installation of the solar collector and the solar system. This
means that that there must not be any shading of the collector during the hours of sunshine and operation of the system, any
water penetration inside the collector from the rain, any accumulation of water in the inside part of the collector cover, any
accumulation of dust or other substances on the outside part of the collector cover, any deformation of any part or area or
material of the collector and system, any leakage in the hydraulic connections in any part of the collector or system, bad or
no insulation of the piping of the solar system, bad operation of the valves of the solar system, non proper maintenance of
the collector and the system and problems caused by deposition of salts within the tubes of the collector by the usage water.
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