PUBLIC REVIEW DRAFT, SEPTEMBER 2008KENYA STANDARD  KS 1851-1:2008  
ICS 27.160 
  
 
 
  
 
  
 
  
 
Thermal solar systems and components — 
Solar collectors — Part 1: General 
requirements 
 
  
 
 
 
 
  
 
  
 
  
 
Public Review Draft, September 2008  
 
 
  
 
  
 
 
© KEBS 2008 Edition 1.0 
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
ii © KEBS 2008 — All rights reserved  
TECHNICAL COMMITTEE REPRESENTATION 
 
The following organizations were represented on the Technical Committee 
 
Kenital Solar (K) Ltd  
ASP Solar (Kenya) Ltd  
Sollatek Ltd  
Department of Electrical & Electronic Engineering, JKUAT  
Renewable Energy Department, Ministry of Energy  
Chloride Exide Kenya Limited  
Energy Alternatives Africa Ltd  
Solarnet  
Automotive and Industrial Battery Manufacturers (AIBM) (K) Ltd 
RENCON Associates  
Telesales Solar Ltd 
Kenya Industrial Research and Development Institute, KIRDI 
Kenya Bureau of Standards — Secretariat 
 
 
 
 
  
 
 
 
 
  
REVISION OF KENYA STANDARDS 
 
In order to keep abreast of progress in industry, Kenya standards shall be regularly reviewed. Suggestions for 
improvement to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are 
welcome. 
 
© Kenya Bureau of Standards, 2008 
 
Copyright. Users are reminded that by virtue of Section 25 of th e Copyright Act, Cap. 12 of 2001  of the Laws of Kenya, copyrig ht 
subsists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bureau  of 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in w riting 
from the Managing Director. 
 
 
 
 
 
 
   
 
 
 
 
 
ISBN PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
ICS 27.160 
© KEBS 2008 — All rights reserved iii  
 
 
 
 
 
 
 
 
  
 
 
Thermal solar systems and components 
— Solar collectors — Part 1: General requirements 
 
 
 
  
 
  
 
  
 
 
KENYA BUREAU OF ST ANDARDS (KEBS) 
 
Head  Office:  P.O. Box 54974, Nairobi-00200, Tel.: (+254  020) 605490, 602350, Fax: (+254 020)  604031 
E-Mail: info@kebs.org,  Web:http://www.kebs.org   
 
KEBS Coast Region 
P.O. Box 99376, Mombasa 80100 
Tel: (+254 041) 229563, 230939/40 Fax: (+254 041) 229448 
E-mail: kebs-msa@swiftmombasa.com
 KEBS Lake Region
P.O. Box 2949, Kisumu 40100 
Tel: (+254 057) 23549,22396 Fax: (+254 057) 21814 E-mail: kebs-ksm@swiftkisumu.com
 KEBS North Rift Region 
P.O. Box 2138, Nakuru 20100 
Tel: (+254 051) 210553, 210555
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
iv © KEBS 2008 — All rights reserved  
Foreword 
 
This Kenya standard was developed by the Renewable Energy Resources Technical Committee under the supervision of the Electrical Industry Standards Committee and is in accordance with the procedures of the 
Bureau. 
 
In respect of potential adverse effects on the quality of water intended for human consumption, caused by the 
product covered by this standard, it is pointed out that:  
a) This standard provides no information as to whether the product may be used without restriction; 
 b) It should be noted that, while awaiting the adoption of verifiable criteria, existing national regulations 
concerning the use and/or the characteristics of this product remain in force. 
  PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008  
© KEBS 2008 — All rights reserved v  
Contents 
 
1 Scope ......................................................................................................................... ................................ 1  
2 Normative references .......................................................................................................... ....................... 1  
3 Terms and definitions ......................................................................................................... ........................ 1  
4 Symbols and units ............................................................................................................. ......................... 1  
5 Durability and reliability .................................................................................................... .......................... 1  
6 Safety ........................................................................................................................ ................................. 4  
7 Collector identification ...................................................................................................... .......................... 4  
Annex A (informative)  Description of solar collectors materials and manufacture ................................................. 6  
Annex B (informative)  Environmental protection ................................................................................................... 8  
Annex C (informative)  Tests to be repeated in collector design modifications ................................................. ..... 9 
Bibliography  .............................................................................................................................. .......................... 10  
 
 
  
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008PUBLIC REVIEW DRAFT, SEPTEMBER 2008KENYA STANDARD KS 1851-1:2008  
© KEBS 2008 — All rights reserved 1  
 
Thermal solar systems and component s — Solar collectors — Part 1: 
General requirements 
 
 1 Scope 
 
This Kenya Standard specifies requ irements on durability (including me chanical strength), reliability and 
safety for liquid heating solar collectors. It also includes provisions for evaluation of conformity to these 
requirements. 
 
It is not applicable to those collectors in which the thermal storage unit is an integral part of the collector to such an extent that the collection process cannot be separated from the storage process for the purpose of 
making measurements of these two processes. It is not applicable to tracking concentrating solar collectors. 
 
Collectors that are custom-built (built-in, roof integrated collectors that do not comprise factory made modules 
and are assembled directly on the place of installation) cannot be tested in their actual form for durability, reliability and thermal performance according to this standard. Instead, a module with the same structure as 
the ready collector is tested. The module gross area in the case of custom built collectors should be at least 2 m
2. The test is valid only for larger collectors, than the tested module. 
 
2 Normative references 
 
The following referenced documents are indispensable for the application of this Kenya Standard. For dated 
references, only the edition cited applies. For undated re ferences, the latest edition of the referenced document 
(including any amendments) applies.  
 
KS 1851-2, Thermal solar systems and components — So lar collectors — Part 2: Test methods  
 
KS ISO 9488, Solar energy — Vocabulary  
 
3 Terms and definitions 
 
For the purposes of this Kenya Standard, the terms and definitions given in KS ISO 9488 apply.  
 
4 Symbols and units 
 
For the purposes of this Kenya Standard, the symbols and units given in KS ISO 9488 and KS 1851-2 apply.  
 
5 Durability and reliability 
 
5.1 Materials and design  
 
Information about the materials and manufacture of solar collectors, including the materials they are 
manufactured of and their resistance to all influences which they might meet in service, retaining their 
operational ability are given in Annex A. 
 
5.2 Required tests  
 
The collector shall be subjected to the following series of tests:  
 
a) Internal pressure for absorber (see 5.2 of KS 1851-2); 
 
b) High temperature resistance (see 5.3 of KS 1851-2);  PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
2 © KEBS 2008 — All rights reserved  
c) Exposure (see 5.4 of KS 1851-2);  
 
d) External thermal shock. May be combined with the high temperature resistance or exposure test (see 5.5 of KS 
1851-2); 
 
e) Internal thermal shock. May be combined with the high temperature resistance or exposure test (see 5.6 of KS 
1851-2); 
 
f) Rain penetration, only for glaz ed collectors (see 5.7 of KS 1851-2);  
 
g) Mechanical load (see 5.9 of KS 1851-2):  
 
h) Thermal performance (see Clause 6 of KS 1851-2);  
 
i) Freeze resistance, only in the cases specified in 5.8 of KS 1851-2;  
 
j) Stagnation temperature (see Annex C of KS 1851-2). May be combined with the high temperature resistance 
or exposure test.  
 
k) Final inspection (see 5.11 of KS 1851-2).  
 
The optional test for impact resistance (see 5.10 of KS 18 51-2) shall be carried out if requested. The result shall be 
recorded.  
 
NOTE Regarding the durability and reliability of elastic materials it is recommended to refer to ISO 9808 and ISO 9553.  
 
5.3 Pass criteria 
 
5.3.1 General 
 
The pass criteria for the reliability tests are given for each test in 5.3.2 to 5.3.10. The term "no major failure", denotes 
that none of the following occurs:  
 
⎯ Absorber leakage or such deformation that permanen t contact between absorber and cover is established;  
 
⎯ Breaking or permanent deformation of cover or cover fixing;  
 
⎯ Breaking or permanent deformation of collector fixing points or collector box;  
 
⎯ Vacuum loss, such that vac uum or subatmospheric collectors shall be classi fied according to the definition in ISO 
9488 (only applicable for vacuum and subatmospheric collectors);  
 
⎯ Accumulation of humidity in form of condensate on the in side of the transparent cover of the collector exceeding 
10 % of the aperture area.  
 
NOTE The evaluation of accumulation of humidity for application of the pass criteria should be applied only on the following te sts: 
 
⎯ external Thermal Shock  
 
⎯ Rain Penetration Test  
 
5.3.2 Internal pressure for absorber  
 
The test pressure shall be as specified in 5.2 of KS 1851-2. In the case of absorbers made of organic 
materials, climate conditions according to Table 2 of KS 1851-2 shall be applied. After the internal 
pressure test, the collector shall not show any major failure as defined in 5.3.1.  
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
© KEBS 2008 — All rights reserved 3 5.3.3 High temperature resistance  
 
When tested in accordance with 5.3 of KS 1851-2, the collector shall not show any major failure as 
defined in 5.3.1.  
 
5.3.4 Exposure  
 
When tested in accordance with 5.4 of KS 1851-2, the collector shall not show any major failure according 
to 5.3.1 and none of each potential problems of their components shall be graded 2 on the scale given in 
B.5.5 of KS 1851-2.  
 
5.3.5 External thermal shock  
 
When tested in accordance with 5.5 of KS 1851-2, the collector shall not show any major failure as 
defined in 5.3.1.  
 
5.3.6 Internal thermal shock  
 
When tested in accordance with 5.6 of KS 1851-2, the collector shall not show any major failure as 
defined in 5.3.1.  
 
5.3.7 Rain penetration  
 
NOTE This test is applicable only for glazed collectors.  
 
A visual check shall not show any water trace. Moreover, at least one of the following shall be fulfilled:  
 
a) by weighing the collector the determined water quantity shall be less than 30 g/m2 or 
 
b) by measuring the humidity inside the collector, any visible droplets inside the collector or humidity that exceeds 20 
g/kg at any time during the test or humidity that doubles from the value measured after stabilization shall yields to 
"major failure" or  
 
c) measured condensation level shall be less than 10 % of the transparent cover and the quantity of the water that 
comes out of the collector when tipping it shall be less than 30 g/m2. 
 
5.3.8 Mechanical load test  
 
When tested in accordance with 5.9 of KS 1851-2 the cover,  the collector box and the fixings between collector box 
and mounting system shall not show any major failure as defi ned in 5.3.1 and 5.9.1.3 of KS 1851-2. The permissible 
and the maximum positive and negative pressure shall be recorded in the installer manual.  
 
5.3.9 Thermal performance  
 
When tested in accordance with Clause 6 of KS 1851-2, the collector shall not show any major failure as defined in 
5.3.1. Thermal performance shall be reported.  
 
5.3.10 Freeze resistance test  
 
This test shall be carried out only in the cases specified in 5.8.1 of KS 1851-2. The pass criterion is no major failure as 
defined in 5.3.1 after three freeze-thaw cycles.  
 
5.4 Procedure  
 
The required number of collectors shall be available for testing. The collectors shall be tested in accordance 
with 5.2. The collectors conform to this standar d, only if all pass criteria are fulfilled. 
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
4 © KEBS 2008 — All rights reserved Freeze resistance shall be tested, for collectors which the manufacturer claims can withstand freezing and 
freeze/thaw cycling and which are not intend ed to be filled with antifreeze fluids. 
 
6 Safety 
 
The maximum fluid temperature to be considered in the desi gn of a solar collector or solar plant is the collector 
stagnation temperature. Materials to be used in the manufactur e of collectors or installations  incorporating the collector 
(expansion tanks, safety valves, etc.) shall be chosen taking into account this temperature.  
 
The stagnation temperature shall be calculated in accord ance with Equation C.1 of KS 1851-2 under the following 
climate parameters:  
 
⎯ Hemispherical irradiance on collector plane 1000 W/m2; 
 
⎯ Surrounding air temperature 30 °C. 
 
Stagnation temperature (see Annex C of KS 1851-2) may be combined with the high temperature resistance or 
exposure test.  
 
The collector shall provide for safe installation and mounting. Sharp edges, loose connections and other potentially 
dangerous features shall be avoided. If the weight of the empty collector exceeds 60 kg, an anchorage for a lifting 
device shall be included, except for the collectors that are assembled on the roof. Collectors filled with a heat transfer 
fluid irritant to human skin or eyes, or toxic, shall carry a warning label. 
 
7 Collector identification 
 
7.1 Drawings and data sheet 
 
The collector submitted for test shall be accompanied by a set of drawings describing the collector's dimensions and 
structure along with a list of materials used in the collector and important physical and optical properties as well as by 
the solar collector description in D.2 or E.2 of KS 1851-2. Drawings shall have a number, date of issue and possible 
revision date. These documents shall be filled by the test inst itute for at least the period of time that the collector type is  
traded by the manufacturer.  
 
NOTE The manufacturer is usually obliged to keep these drawings for at least the period of time that the warranty of the collector type is 
valid. 
 
7.2 Labelling  
 
Collectors shall carry a visible and durable label with the following data:  
 
⎯ Name of manufacturer;  
 
⎯ Type;  
 
⎯ Serial number;  
 
⎯ Year of production;  
 
⎯ Gross area of collector;  
 
⎯ Dimensions of collector;  
 
⎯ Maximum operation pressure;  
 
⎯ Stagnation temperature at 1000 W/m2 and 30 °C;  
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
© KEBS 2008 — All rights reserved 5 ⎯ Volume of heat transfer fluid;  
 
⎯ Weight of empty collector: ……………… ……………….. Made in: … ………………............... 
 
7.3 Installer instruction manual  
 
Solar collectors shall be accompanied by an installer instru ction manual, if traded as stand-alone components. When 
they are part of a complete system, th e system installation manual can cover the complete system. In that case no 
separate manual for the collector shall be required. The instruction manual shall at least contain the following 
information:  
 
⎯ dimensions and weight of the collector, instructions  about the transport and handling of the collector;  
 
⎯ description of the mounting procedure;  
 
⎯ recommendations about lightning protection;  
 
⎯ instructions about the coupling of the collectors to one an other and the connection of the collector field to the heat 
transfer circuit, including dimensions of pipe connections for collector arrays up to 20 m2; 
 
⎯ recommendations about the heat transfer media which may be used (also with respect to corrosion) and 
precautions to be taken during filling, operation and service; 
 
⎯ maximum operation pressure, the pressure drop and the maximum and minimum tilt angle;  
 
⎯ permissible wind and snow load;  
 
⎯ maintenance requirements. 
 
If the collector is traded as a component and sold direct ly to customers, all relev ant documentation concerning 
personal safety, maintenance and handling of the product sh all be made available to the customer in the national 
language of the country where it is sold. 
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
6 © KEBS 2008 — All rights reserved  
Annex A 
(informative) 
 
Description of solar collectors materials and manufacture 
 
A.1 General  
 
The operational ability and long lifetime of solar collectors  depend on the correct choice of appropriate materials. 
Testing of the materials, including accelerated life testing,  is very important for the development of new collectors 
and the prediction of service life. Respective li terature is referred to in the Bibliography. 
 
Solar collectors may be affected by airborne fire or radiant heat. The use of non-combustible materials should be 
preferred. Collectors should comply with the regulations to fire-classification. 
 
The collector box should be water-tight to prevent penetration of rain water. The collector box should be 
constructed in such a way that condensed water does not accumulate in the collector, as this might impair its 
functional capability and durability. Fo r that purpose the collector should  be properly designed to enable 
ventilation of air through the collector box. 
 
The construction of the collector should ensure that no undue stress is built up in the cover, even at the 
maximum stagnation temperature of the collector. The materi als of collector components should be selected and 
constructed so that they can withstand the maximum temperature which may occur at stagnation conditions and 
the thermal shocks they may be exposed to during the su mmer period. The materials of the collector should 
preferably be resistant to exposure to UV-radiation and in cases where materials selected are not so, they should 
be protected against incident and reflected UV-radiation. 
 
Bushings and ducts, leading through the box, should be constructed so that no leakage can occur caused by 
thermal expansion. The collector box bushings should wi thstand any damage, if they have to be soldered for 
assembly. The design of collector should be such that he at bridges between the collector box and the absorber 
are avoided. 
 
The components and the materials of the collector should be able to withstand the mechanical loads resulting 
from the heating up and cooling down of the collector. They should also be resistant to environmental stress from 
outdoor climate caused by factors such as rain , snow, hail, wind, high humidity and air pollutants.  
 
A.2 Absorbers  
 
Absorbers should be made from suitable materials to cope with mechanical, thermal and chemical requirements 
of the application. The effect of the manufacturin g processes like cutting, brazing, soldering etc., on the 
properties of the absorber, should be considered.  
 
The absorber ducts which guide the flow of the heat transfer fluid, including the connection lines, should be 
designed and constructed in such a way that venting can be effected in the installed condition, thus ensuring the 
functional capability of the collector. 
 
Absorbers should be dimensioned on the basis of a calculation pressure corresponding to the permissible 
working overpressure specified by the manufacturer taking into consideration a safety factor of 1.5. The 
properties of the heat transfer medium should be considered as well.  
 
The effect of the maximum temperature (stagnation temperature) of the absorber should be considered in the 
selection of material.  
 
In the case of materials with strength characteristics, wh ich vary appreciably with the te mperature and/or UV-exposure, 
the evaluation criteria should be determined individually in each case.  
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
© KEBS 2008 — All rights reserved 7 The wetted side of the absorber should withstand corrosion under normal operating conditions and taking into account 
the admixture of possible additives to the heat transfer fl uid. The walls of swimming pool collectors which are wetted by 
the swimming pool water should be resistant to the additives used for the treatment of the swimming pool water. 
 
Absorber coatings should retain their optical properties under high temperature, high humidity and condensation, and 
sulfur dioxide at high humidity. 
 
A.3 Transparent covers  
 
Solar collectors are generally covered with glass or transparent plastic glazing. The durability of glass and tempered 
glass under the service conditions found in solar collectors is good, but the resistance of plastics and glass treated with 
a special coating to the combined effects of UV radiation and temperature may be poor. There may be significant 
degradation with time, and in the case of a reduced transmission in the solar wavelengths, this will lead to degradation in 
collector performance. A reduction in the tensile strength or impact strength of a cover material may lead to a failure of 
the collector cover. 
 
The transparency of the covers should not deteriorate appreciably during the service life of the collector, the covers 
should be resistant to ultraviolet (UV) radiation, air pollution, high humidity and condensate as well as high 
temperatures depending on the collector design. 
 
A.4 Insulation materials  
 
Insulation materials should withstand the local temperature arising during sta gnation temperature conditions of the 
collector. At this temperature no melting, shrinkage or outgas ing of the insulation with consequent condensation inside 
the collector cover, or absorber performa nce reduction or corrosion of metallic su rfaces should occur to the extent of 
seriously reducing the collector performance. 
 
Water or humidity absorption by the insulation material may shortly or permanently reduce the insulation performance 
of the material. 
 
Thermal expansion of the material used in the collector due to the wide range of temperat ures should be taken into 
consideration because of different thermal expansion coeffi cients. Furthermore transparent insulation materials or 
teflon layers used, should not deteriorate appreciably, both mechanically and optically, during the service life of the 
collector due to ultraviolet (UV) radi ation, high temperature and humidity. 
 
A.5 Reflectors 
 
Reflectors, diffuse or specular, are refl ecting surfaces used to increase the r adiation, incident on the absorber. The 
reflecting surface should be resistant to environmental in fluences such as air pollution and to corrosion through 
humidity or rain. Outside the collector box reflectors should also resist mechanical loads through wind, snow and hail, 
whereas inside reflectors should withstand high temperatures. 
 
A.6 Diffusion barriers 
 
Diffusion barriers are materials used between absorbers and insulation material to prevent diffusion into or out of the 
insulation material. They should be able to withstand the absorber high temperatures and the incident UV radiation 
without shrinking and the high humidity or condensate accumulated remaining tight. 
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
8 © KEBS 2008 — All rights reserved  
Annex B 
(informative) 
 
Environmental protection 
 
B.1 Heat transfer fluid  
 
The heat transfer fluid used should not be toxic, seriously irritant to the human skin or eyes, or water polluting and it 
should be fully biodegradable.  
 
B.2 Insulation materials  
 
For the collector insulation no materials should be used,  which have been manufactured using or containing CFCs. 
Furthermore, the insulation materials should not contain components, which outgas at the stagnation temperature, 
specified in Clause 6, which are toxic and se riously irritant to the human skin or eyes.  
 
B.3 Recycling of the collector materials 
 
Solar collectors are mainly used to save energy and reduce pollution. Therefore the design of the collectors should take 
into consideration the possibility to recycle the materials used. Materials which are not to be recycled should be avoided 
or used to the lowest possible extent. 
 
 
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
© KEBS 2008 — All rights reserved 9  
Annex C 
(informative) 
 
Tests to be repeated in collector design modifications 
 
If the collector design is changed, Table C.1 may be used as  a guideline to assess whether one or more tests should 
be repeated.  
 
Table C.1 ⎯ Tests that should be repeated for the respective modification in the collector design 
 
 
 Absorbers  
 Covers  
 Insulation materials
 Boxes  
 Reflectors  
 Diffusion barriers  
 
Thermal performance  
 + 
 + 
 + 
 + 
 + 
 + 
 
Internal pressure  
 + 
 - 
 - 
 - 
 - 
 - 
 
High temp, resistance  
 + 
 + 
 + 
 + 
 + 
 + 
 
Exposure  
 + 
 + 
 + 
 + 
 + 
 + 
 
External thermal shock  
 - 
 + 
 - 
 + 
 + 
 - 
 
Internal thermal shock  
 + 
 - 
 - 
 - 
 - 
 - 
 
Rain penetration  
 - 
 + 
 - 
 + 
 - 
 - 
 
Mechanical tests  
 - 
 + 
 - 
 + 
 - 
 - 
 
Final inspection  
 + 
 + 
 + 
 + 
 + 
 + 
 
+ Test should be repeated  
 
- Test need not be repeated  
 
 PUBLIC REVIEW DRAFT, SEPTEMBER 2008KS 1851-1:2008 
10 © KEBS 2008 — All rights reserved  
Bibliography 
 
[1] KS ISO 9806-1, Test methods for solar collectors ⎯ Part 1: Thermal performance of glazed liquid heating collectors 
including pressure drop . 
 
[2] KS ISO 9806-2, Test methods for solar collectors ⎯ Part 2: Qualification test procedures  
 
[3] KS ISO 9806-3, Test methods for solar collectors ⎯ Part 3: Thermal performance of unglazed liquid heating 
collectors (sensible heat transfer only) including pressure drop  
 
[4] KS ISO 9808, Solar water heaters ⎯ Elastomeric materials for absorbers, connecting pipes and fittings ⎯ Method 
of assessment  
 
[5] KS ISO/TR 10217, Solar energy ⎯ Water heating systems ⎯ Guide to material selection with regard to internal 
corrosion  
 
[6] NF P 50-511:1985, Solar energy ⎯ Solar collectors using heat transfer liquid ⎯ Suitability for use  
 
[7] DIN V 4757-3:1995, Solar heating systems ⎯ Part 3: Solar collectors, definitions, safety requirements, test of 
stagnation temperature  
 
[8] ONORM M 7710:95, Solar collectors for use of solar energy ⎯ Performance requirements, test specifications and 
procedures  
 
[9] UNI 8796:1987, Solar systems ⎯ Liquid solar collectors ⎯ Acceptance criteria  
 
[10] E. Aranovitch, D. Gilliaert, W.B.  Gillet, J.E. Bates EUR 11606 Recommen dations for Performance and Durability 
Tests of Solar Collectors and Water Heating Systems. Lu xembourg:  Office for Official Publications of the 
European Communities, 1989  
 
[11] Paradissiadis I.. Siskos B ., Tzamouranis H.: Proposal for a Greek stan dard for the certification of active solar 
systems. CRES, Greece, 1994  
 
[12] Wennerholm H.: Rules for P-Marking of Thermal Solar Collectors. SP, Swedish National Testing and Research 
Institute, Energy Technology CEN TC 312/N16, 1994  
 
[13] ISO 9553:1997, Solar energy — Methods of testing preformed rubber seals and sealing compounds used in 
collectors  
 
[14] ISO 9495, Solar energy ⎯ Transparent covers for collectors ⎯ Ageing test under stagnation conditions  
 
[15] Carlsson B., Frei U., Koehl M., Moeller K.: Accelerated life testing of solar energy materials . Case study of some 
selective solar absorber coating materials for DHW-system s. A report of Task X, solar materials research and 
development, international Energy Agency, Solar Heat ing and Cooling Programme. February 1994. SP-Report 
1994:13, ISBN 91-7848-472-3