ISO 9806-2:1995

Test methods for solar collectors — Part 2: Qualification test procedures

Establishes test methods for testing solar collectors under well-defined and repeatable conditions. Determination of the ability to resist the influences of degrading agents.

Méthodes d'essai des capteurs solaires — Partie 2: Méthodes d'essai de qualification

Metode za preskus sprejemnikov sončne energije - 2. del: Ovrednotenje preskusnih postopkov

General Information

• Status: Withdrawn
• Publication Date: 16-Aug-1995
• Withdrawal Date: 16-Aug-1995
• ICS: 27.160 - Solar energy engineering
• Technical Committee: ISO/TC 180 - Solar energy
• Drafting Committee: ISO/TC 180 - Solar energy
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 05-Nov-2013
• Ref Project: SIST ISO 9806-2:1997 - Test methods for solar collectors -- Part 2: Qualification test procedures

Relations

• Revised: ISO 9806:2013 - Solar energy — Solar thermal collectors — Test methods
• Effective Date: 11-Jun-2011

Standards Content (Sample)

INTERNATIONAL
Is0
STANDARD
9806-2
First edition
1995-08-I 5
Test methods for solar collectors -
Part 2:
Qualification test procedures
Mbthodes d’essai des capteurs solaires -
Partie 2: M&hodes d’essai de qualification
Reference number
IS0 9806-2: 1995(E)

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IS0 9806-2: 1995(E)
Contents
Page
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
5 Internal pressure tests for absorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
6 High-temperature resistance test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Exposure test . . . . . . . . . . . . . . .~. 13
8 External thermal shock test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 14
9 Internal thermal shock test for liquid-heating collectors . 16
IO Rain penetration test . 17
11 Freezing test . 18
12 Impact resistance test (optional) . 20
13 Final inspection . 21
...................................... ....................................... 21
14 Test report
Annexes
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
A Test format sheets
.............. 46
B Stagnation temperature of liquid heating collectors
48
C Bibliography .
0 IS0 1995
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
II

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0 IS0
IS0 9806-2: 1995(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 9806-2 was prepared by Technical Committee
lSO/TC 180, Solar energy, Subcommittee SC 5, Collectors and other
components.
IS0 9806 consists of the following parts, under the general title Test
methods for solar collectors:
- Part 7: Thermal performance of glazed liquid heating collectors in-
cluding pressure drop
- Part 2: Qualification test procedures
- Part 3: Thermal performance of unglazed liquid heating collectors
(sensible heat transfer only) including pressure drop
Annexes A and B form an integral part of this part of IS0 9806. Annex C
is for information only.
. . .
III

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0 IS0
IS0 9806-2: 1995(E)
Introduction
It is widely recognized that the durability and reliability of solar collectors
and solar collector systems are of great importance when the overall
quality of a solar heating system is being assessed.
Collectors are required to resist a number of influences which can be
clearly identified and quantified, such as high internal fluid pressures, high
temperatures and rain penetration. Tests to establish the extent to which
a collector is able to resist these influences are commonly called “quali-
f ication tests “.

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INTERNATIONAL STANDARD 0 IS0 60 9806-2: 1995(E)
Test methods for solar collectors -
Part 2:
Qualification test procedures
1 Scope
1.1 This part of IS0 9806 establishes test methods for determining the ability of a solar collector to resist the
influences of degrading agents.
1.2 This part of IS0 9806 applies to all types of solar collectors, including integral collector storage systems but
excepting tracking concentrating collectors.
1.3 This part of IS0 9806 defines procedures for testing collectors under well-defined and repeatable conditions,
but does not include pass/fail criteria for the test results.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part
of IS0 9806. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of IS0 9806 are encouraged to investigate the possibility of applying the
most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently
valid International Standards.
Specifica fion and classification of jnstrumen ts for measuring hemispherical solar
IS0 9060: 1990, Solar energy -
and direct solar radiation.
IS0 9459-l :I 993, Solar heating - Domestic water heating systems - Part 7: Performance rating procedure using
indoor test methods.
Domestic water heating systems - Part 2: Outdoor test methods for system
IS0 9459-2:1995, Solar heating -
performance characterization and yearly performance prediction of solar-only systems.
Part 7: Thermal performance of glazed liquid heating co/-
IS0 9806-I : 1994, Test methods for solar collectors -
lectors including pressure drop.
I SO 9806-3: -1) Test methods for solar collectors - Part 3: Thermal performance of unglazed liquid heating CO/-
lectors (sensibl; heat transfer only) including pressure drop.
I) To be published.
1

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0 IS0
IS0 9806=2:1995(E)
3 Definitions
For the purposes of this part of IS0 9806, the definitions given in IS0 9806-I and the following definitions apply.
ector in which the space between the absorber and the cover is evacuated to a
3.1 collector, evacuated: Col
pressure < 3 kPa.
system: Solar heating system in which the solar collector also functions as a heat
3.2 integral collector storage
(water) storage tank.
33 irradiation: Incident energy per unit area of surface, found by the integration of irradiance over a specified
time interval.
It is normally expressed in megajoules per square metre.
The time interval specified is often an hour or a day.
NOTE 1
3.4 stagnation conditions (in solar energy systems): Conditions of temperature and pressure existing when the
system has attained a quasi-steady state after the flow of the heat transfer fluid has stopped, but the absorber
continues to receive significant solar radiation.
3.5 steady-state: Status of a solar collector when the heat removal rate (including losses) is equal to the solar
energy input rate.
4 General
The tests in this part of IS0 9806 shall be carried out in the sequence shown in table 1, using three collectors (A,
B and C) of any given type.
Tests may be omitted from the sequence upon agreement of all parties involved or at the discretion of the test
laboratory. Changes in the test sequence shall be reported with the test results and the reasons for deviation shall
be given.
For some qualification tests, a part of the collector may have to be tampered with in some way, for example a hole
may have to be drilled in the back of the collector to attach a temperature sensor to the absorber. In these cases
care should be taken to ensure that any damage caused does not affect the results of subsequent qualification
tests, for example by allowing water to enter into a previously raintight collector.
NOTE 2 This sequence has been determined with a view to minimizing test costs while ensuring that the possible effects
of each degrading influence are likely to be evaluated in a later test. (For example, rain penetration may result if a collector is
distorted by exposure to high temperatures.)
5 Internal pressure tests for absorbers
5.1 Metallic absorbers for liquid heating collectors
5.1 .I Objective
The absorber is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service.
5.1.2 Apparatus and procedure
The apparatus, shown in figure 1, consists of a hydraulic pressure source (electrical pump or hand pump), a safety
valve, an air-bleed valve and a pressure gauge with an accuracy of 5 % of the actual reading. The air-bleed valve
shall be used to empty the absorber of air before pressurization.
2

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0 IS0
IS0 9806-2: 1995(E)
The metallic absorber is filled with water at room temperature and pressurized to the test pressure for the test
period. This pressure is maintained while the absorber is inspected for swelling, distortion or ruptures.
Table 1 - Test sequence
Test
Sequence Clause Collector
1 5 Internal pressure A
A
2 6 High-temperature resistance’)
A, B and C
3 7 Exposure
A
4 8 External thermal shock*)
5 9 Internal thermal shock A
A
6 10 Rain penetration
A
7 11 Freeze resistance
5 Internal pressure (retest) A
8
I
9 Thermal performances) A
12 Impact resistance (optional) A or B
IO
Final inspection
11 13 A, B and C
I) For organic absorbers, the high-temperature resistance test shall be performed first in order to determine the collector
stagnation temperature needed for the internal pressure test.
2) The external thermal shock test may be combined with the exposure test.
3) The thermal performance test shall be carried out in accordance with the procedures given in IS0 9806-I or IS0 9806-3
for glazed or unglazed liquid heating collectors and IS0 9459-l or IS0 9459-2 for integral collector storage systems.
Air-bleed
valve
Fluid pipe sealed
ssure Safety
valve
Collector with
pressure
source
- Schematic for internal pressure test of metallic absorbers for liquid heating collectors
Figure 1

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IS0 9806-2: 1995(E)
5.1.3 Test conditions
5.1.3.1 Temperature
absorbers are pressure-tested at ambient temperature within the range 5 “C to 30 “C.
Metallic
5.1.3.2 Pressure
times the maximum
The test pressure is either th e manufacturer’s stated maximu m test press ure or I,5 collector
operating pressure specified by the manufactu rer, whichever is lower.
The test pressure is maintained for 10 min.
5.1.4 Results
The collector shall be inspected for leakage, swelling and distortion. The results of this inspection shall be reported
together with the values of pressure and temperature used and the duration of the test. If the applied test pressure
was less than I,5 times the maximum collector operating pressure specified by the manufacturer, this shall be
reported.
5.2 Liquid heating absorbers made of organic materials (plastics or elastomers)
5.2.1 Objective
The absorber is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service while operating at elevated temperature. The tests are carried out at elevated temperatures, because
the pressure resistance of an organic absorber may be adversely affected as its temperature is increased.
5.2.2 Apparatus and procedure
neumatic pressure source, and a means of heating the absorber
The apparatus consi sts of either a hydraulic or a p
to the required test temperature
The characteristics of a solar irradiance simulator shall be the same as those of the simulator used for steady-state
efficiency testing of liquid heating solar collectors (see IS0 9806-I).
The test conditions specified in 5.2.3 shall be maintained for at least 30 min prior to test and for the full duration
of the test.
The pressure in the absorber is raised in stages as specified in 5.2.3, and the absorber is inspected for swelling,
distortion or rupture after each increase in pressure. The pressure is maintained while the absorber is being in-
spected.
For safety reasons, the collector shall be encased in a transparent box to protect personnel in the event of ex-
plosive failure during this test.
5.2.2.1 Organic absorbers for use in unglazed collectors (test temperature < 90 “C)
Where the maximum test temperature is below 90 “C, absorbers may be submerged in a heated water bath and
pressure-tested. The pressurized fluid supply to the absorber shall be fitted with a safety valve, air-bleed valve (if
required) and pressure gauge having an accuracy of 5 % of the actual reading. Apparatus is shown in figure 2.
5.2.2.2 Organic absorbers for use with oil-based fluids (test temperature > 90 “C)
When the test temperature exceeds 90 “C, the absorber may be connected to a hot oil circuit. The absorber and
hot oil circuit are then pressurized. The hot oil circuit shall be fitted with a safety valve, air-bleed valve and pressure
gauge having an accuracy of 5 % of the actual reading.
4

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0 IS0
IS0 9806=2:1995(E)
The absorber may be heated by any of the following methods:
a) connecting a heater in the oil circuit (figure3);
b) heating the whole collector in a solar irradiance simulator (figure4);
c) heating the whole collector outdoors under natural solar irradiance (figure4).
Safety measures should be taken to protect personnel from hot oil in the event of explosive failure during this test.
5.2.2.3 Organic absorbers - high-temperature pneumatic pressure test
The absorber may be pressure-tested using compressed air, when heated by either of the following methods:
a) heating the whole collector in a solar irradiance simulator (figure5);
b) heating the whole collector outdoors under natural solar irradiance (figure 5).
The compressed air supply to the absorber shall be fitted with a safety valve and a pressure gauge having an ac-
curacy of 5 % of the actual reading.
Safety Pressure
valve
ww
Air-bleed vaive
(for hydraulic
Hydraulic or
testing only)
pneumatic
pressure source
Temperature sensor
Organic absorber
L
Heated water bath
Schematic for internal pressure test of organic absorbers for use in unglazed collectors
Figure 2 -
5

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IS0 9806-2: 1995(E)
Air-bleed
valve
Fluid pipe sealed
Hot oil
source
Safety
valve
Temperature
sensor
organic absorber
Circulating
pump
Figure 3 - Schematic for internal pressure test of organic absorbers for use with oil-based fluids (hot oil
source)
Air-bleed
valve
Natural or simulated
A
solar radiation
I
ture
Pyranometer on
collector plane
Fluid pipe
Hydraulic
pressure
source
Figure 4 - Schematic for internal pressure test of organic absorbers for use with oil-based fluids (test
under solar irradiance)

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IS0 9806-2: 1995(E)
Natural or simulated
solar radiation
Ambient
tempera ture
se nsor
Pressure Safety
valve
ww e
Pyranometer on
Collector with
collector plane
organic absorber
Pneumati
pressure
source
Fl uid pipe se
Figure 5 - Schematic for internal pressure test of organic absorbers (pneumatic test under solar
irradiance)
5.2.3 Test conditions
5.2.3.1 Temperature
For absorbers made of organic materials, the test temperature is the maximum temperature which the absorber
will reach under stagnation conditions.
One of the alternative sets of reference conditions given in table 2 shall be used to determine the test temperature,
depending on the climate in which the collector will be used.
The calculations employed to determine the test temperature are included in annex B and shall either:
- use measured collector performance characteristics, or
- extrapolate from average values, measured in the high-temperature resistance test (6.3), of the global solar
irradiance (natural or simulated) on the collector plane, the surrounding air temperature and the absorber tem-
perature.
The test temperature for integral collector storage systems shall be 85 “C for class A and class B climate reference
conditions and 100 “C for class C.
- Climate reference conditions to determine test temperatures for internal pressure test of
Table 2
organic absorbers
Value for climate class
Climate parameter
Class A Class B Class C
Temperate Sunny
Very sunny
1 000 1 100
Global solar irradiance on collector plane, G (W/m*) > 1 200
Surrounding air temperature, ta (“C) 30 40
> 40
7

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0 IS0
IS0 9806-2: 1995(E)
5.2.3.2 Pressure
The test pressure shall be I,5 times the maximum collector operating pressure specified by the manufacturer.
For absorbers made of organic materials, the pressure shall be raised to the test pressure in equal stages of
0,2 bar*) (approximately) and maintained at each intermediate pressure for 5 min. The test pressure shall then be
maintained for at least 1 h.
5.2.4 Results
The collector shall be inspected for leakage, swelling and distortion. The results of the inspection shall be reported.
Full details of the test procedure used, including the temperature, intermediate pressures and test periods used,
shall be reported with the test results.
53 . Air heating collectors with metallic absorbers
5.3.1 Objective
The collector is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service, including pressures which may arise when the airflow is blocked on the other side of the collector from
the fan.
5.3.2 Apparatus and procedure
The apparatus, shown in figure6, consists of a controllable air source or suction fan, capable of supplying the
specified values of positive or negative pressure at the maximum allowable collector leakage flowrate. An airflow
meter having an accuracy of 5 % is installed to measure the rate of leakage, and a pressure gauge having an ac-
curacy of 5 % of the actual reading is installed to measure the pressure in the absorber.
Pressure
gauge
collector with
Leaka Air source or
w
airflo w meter sue tion fan
Schematic for internal pressure test of air heating collectors with metallic absorbers
Figure 6 -
The air source or suction fan, airflow meter and pressure gauge are connected to the collector, and other pipe
connections to the collector are sealed.
The collector is brought to the test pressure with air at ambient temperature, for the specified test period.
The collector is maintained at the test pressure while it is inspected for swelling, distortion or ruptures.
For safety reasons, the collector shall be encased in a transparent box to protect personnel in the event of ex-
plosive failure during this test.
2) 1 bar = 100 kPa.
8

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0 IS0
IS0 9806=2:1995(E)
5.3.3 Test conditions
5.3.3.1 Temperature
Air heating collectors with metallic absorbers are pressure-tested at ambient temperature.
5.3.3.2 Pressure
The test pressure is I,2 times the maximum collector operating pressure difference above or below atmospheric
pressure, as specified by the manufacturer.
The test pressure is maintained for 10 min.
5.3.4 Results
The collector shall be inspected for swelling, distortion or ruptures. The results of the inspection shall be reported
together with the rate of air leakage, and the values of pressure and temperature and the test period used for the
test.
5.4 Air heating absorbers made of organic materials (plastics or elastomers)
5.4.1 Objective
The collector is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service, including pressures which may arise when the airflow is blocked on the other side of the collector from
the fan. Because the pressure resistance of collectors with absorbers made of organic materials is expected to
be significantly reduced at higher temperatures, a pressure test at an elevated temperature shall be used.
5.4.2 Apparatus and procedure
The apparatus (see figure 7) consists of a controllable air source or suction fan, capable of supplying the specified
values of positive or negative pressure at the required temperature, and at the maximum allowable collector
leakage flowrate. A flowmeter having an accuracy of 5 % to measure the leakage and a pressure gauge having
an accuracy of 5 % of the readings taken during the test are also required.
Circulating fan
Air heater
Temperature fi
sensor
Figure 7 - Schematic for internal pressure test of air heating collectors with organic absorbers

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(0 IS0
IS0 9806-2: 1995(E)
The collector is connected to an air-heating loop in such a way that air flows downwards into the collector. The
pressure gauge is connected to the collector either in a separate opening of the collector or in the heating loop
close to the outlet of the collector. While circulating air through the collector, the air is heated to the test tem-
perature and maintained there for the test period. The collector and the heating loop are pressurized or depress-
urized in stages to the test pressure, which is then maintained for the test period.
After the test period, the temperature and pressure are maintained while the collector is inspected for swelling,
distortion or ruptures. The collector is also inspected for swelling, distortion or ruptures after each rise in pressure.
For safety reasons, the collector shall be encased in a transparent box to protect personnel in the event of ex-
plosive failure during this test.
5.4.3 Test conditions
5.4.3.1 Temperature
which the absorber
absorbers made of organic materials, the test temperature is the maximum temperature
For
will reach under stagnation conditions.
One of the alternative sets of reference conditions given in table 2 shall be used to determine the test temperature,
depending on the climate in which the collector will be used.
The test temperature shall be determined from measurements made during the high-temperature resistance test
specified in clause 6, using the expression included in annex B.
5.4.3.2 Pressure
The test pressure shall be I,2 times the maximum collector operating pressure difference above or below at-
mospheric pressure, as specified by the manufacturer.
For absorbers made of organic materials, the pressure shall be raised to the test pressure in equal stages of
0,2 bar (approximately) and maintained at each intermediate pressure for 5 min. The test pressure shall then be
maintained for at least 1 h.
5.4.4 Results
The collector shall be inspected for leakage, swelling and distortion. The results of the inspection shall be reported.
Full details of the test procedure used, including the temperature, intermediate pressures and test periods selec-
ted, shall be reported with the test results.
6 High-temperature resistance test
6.1 Objective
This test is intended to assess rapidly whether a collector can withstand high irradiance levels without failures such
as glass breakage, collapse of plastic cover, melting of plastic absorber, or significant deposits on the collector
cover from outgassing of collector material.
6.2 Apparatus and procedure
The collector shall be tested outdoors, or in a solar irradiance simulator, or in a hot fluid loop of the type described
in 5.2.2.2. A schematic for testing outdoors or in a simulator is shown in figure 8.
The characteristics of the solar irradiance simulator to be used for the high-temperature resistance test shall be
those of the solar irradiance simulator used for steady-state efficiency testing of liquid heating solar collectors in
accordance with IS0 9806-I.
10

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IS0 9806=2:1995(E)
A
Natur aL or simulated
solar radiation
lid
Ambient
temperature
FL sensor
Le
Pyranometer on
collector plane
J Fluid pipe sealed
L
Figure 8 - Schematic for high-temperature resistance test (outdoors or in simulator)
If a hot fluid loop is used, the hot fluid shall be circulated from the bottom to the top of the collector with a constant
inlet temperature, using a flowrate similar to that defined for collector efficiency testing (see IS0 9806-I).
NOTE 3 It is recognized that the thermal stresses induced by the hot fluid loop test may not be equivalent to the thermal
stresses induced by heating externally using natural or simulated solar irradiance.
The collector is mounted outdoors or in a solar simulator, and it is not filled with fluid. All of its fluid pipes are
sealed to prevent cooling by natural circulation of air except one, which is left open to permit free expansion of
air in the absorber.
A temperature sensor is attached to the absorber to monitor its temperature during the test. The sensor shall be
positioned at two-thirds of the absorber height and half the absorber width. It shall be fixed firmly in a position to
ensure good thermal contact with the absorber. The sensor shall be shielded from solar radiation.
NOTES
4 When testing collectors, such as evacuated tubular collectors, for which it is not appropriate to measure the stagnation
temperature at the absorber, the temperature sensor should be placed at a suitable location in the collector, and this location
should be clearly described with the test results.
5 In some cases, such as evacuated absorbers, it may be difficult to attach a thermocouple to the absorber. In such cases,
instead of attaching a thermocouple to the absorber, the testing laboratory may partially fill the absorber with a special fluid,
seal the absorber and measure the pressure in the absorber. The relationship between the internal pressure in the absorber
and its temperature should be known from the standard vapour pressure/temperature relationship for the fluid.
The test is performed for a minimum of 1 h after steady-state conditions have
been established, and the collector
65 . .
is subsequently inspected for signs of damage as specified in
11

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0 IS0
IS0 9806-2: 1995(E)
6.3 Test conditions for testing outdoors or in a solar irradiance simulator
One of the alternative sets of reference conditions given in table3 shall be used, depending on the climate in
which the collector will be used.
Table 3 - Climate reference conditions for high-temperature resistance test
Value for climate class
4-- I
Climate parameter
Class A Class B Class C
Temperate Sunny Very sunny
Global solar irradiance
on collector plane, G (W/m*) 950 - 1 049 1 050 - 1 200 > 1 200
25,0 - 29,9 30 - 40 > 40
Surrounding air temperature, ta (“C)
Surrounding air speed (m/s)
I I
6.4 Test conditions for testing in a hot fluid loop
If a hot fluid loop is used, then the fluid temperature to be used in the test is the maximum temperature which
the collector will reach under stagnation conditions.
One of the alternative sets of reference conditions given in table 2 shall be used to determine the test temperature,
depending on the climate in which the collector will be used.
The calculations employed to determine the test temperature are included in annex B and shall either:
- use measured collector performance characteristics, or
- extrapolate from average values of solar irradiance (natural or simulated) on the collector plane, surrounding air
temperature and absorber temperature, measured by exposing the collector to available climate conditions
(outdoors, or in a solar simulator) under stagnation conditions for at least 1 h.
The fluid test temperature for integral collector storage systems shall be 85 “C for class A and class B climate
reference conditions and 100 “C for class C.
6.5 Results
The collector shall be inspected for degradation, shrinkage, outgassing and distortion.
For tests outdoors or in a solar irradiance simulator, the results of the inspection shall be recorded together with
the average values of solar irradiance (natural or simulated) on the collector plane, surrounding air temperature and
speed, and absorber temperature (and the pressure of the special fluid in the absorber, if that method is used)
recorded during the test.
For tests in a hot fluid loop, the results of the inspection shall be recorded together with the
- average values of the stagnation parameters (irradiance, surrounding air temperature and speed, and absorber
temperature) measured under the available climate conditions;
- calculated test (stagnation) temperature determined for the climate refer
...

SLOVENSKI STANDARD
SIST ISO 9806-2:1997
01-marec-1997
0HWRGH]DSUHVNXVVSUHMHPQLNRYVRQþQHHQHUJLMHGHO2YUHGQRWHQMH
SUHVNXVQLKSRVWRSNRY
Test methods for solar collectors -- Part 2: Qualification test procedures
Méthodes d'essai des capteurs solaires -- Partie 2: Méthodes d'essai de qualification
Ta slovenski standard je istoveten z: ISO 9806-2:1995
ICS:
27.160 6RQþQDHQHUJLMD Solar energy engineering
SIST ISO 9806-2:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 9806-2:1997

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SIST ISO 9806-2:1997
INTERNATIONAL
Is0
STANDARD
9806-2
First edition
1995-08-I 5
Test methods for solar collectors -
Part 2:
Qualification test procedures
Mbthodes d’essai des capteurs solaires -
Partie 2: M&hodes d’essai de qualification
Reference number
IS0 9806-2: 1995(E)

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SIST ISO 9806-2:1997
IS0 9806-2: 1995(E)
Contents
Page
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
5 Internal pressure tests for absorbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
6 High-temperature resistance test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Exposure test . . . . . . . . . . . . . . .~. 13
8 External thermal shock test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 14
9 Internal thermal shock test for liquid-heating collectors . 16
IO Rain penetration test . 17
11 Freezing test . 18
12 Impact resistance test (optional) . 20
13 Final inspection . 21
...................................... ....................................... 21
14 Test report
Annexes
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
A Test format sheets
.............. 46
B Stagnation temperature of liquid heating collectors
48
C Bibliography .
0 IS0 1995
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
II

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SIST ISO 9806-2:1997
0 IS0
IS0 9806-2: 1995(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 9806-2 was prepared by Technical Committee
lSO/TC 180, Solar energy, Subcommittee SC 5, Collectors and other
components.
IS0 9806 consists of the following parts, under the general title Test
methods for solar collectors:
- Part 7: Thermal performance of glazed liquid heating collectors in-
cluding pressure drop
- Part 2: Qualification test procedures
- Part 3: Thermal performance of unglazed liquid heating collectors
(sensible heat transfer only) including pressure drop
Annexes A and B form an integral part of this part of IS0 9806. Annex C
is for information only.
. . .
III

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SIST ISO 9806-2:1997
0 IS0
IS0 9806-2: 1995(E)
Introduction
It is widely recognized that the durability and reliability of solar collectors
and solar collector systems are of great importance when the overall
quality of a solar heating system is being assessed.
Collectors are required to resist a number of influences which can be
clearly identified and quantified, such as high internal fluid pressures, high
temperatures and rain penetration. Tests to establish the extent to which
a collector is able to resist these influences are commonly called “quali-
f ication tests “.

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SIST ISO 9806-2:1997
INTERNATIONAL STANDARD 0 IS0 60 9806-2: 1995(E)
Test methods for solar collectors -
Part 2:
Qualification test procedures
1 Scope
1.1 This part of IS0 9806 establishes test methods for determining the ability of a solar collector to resist the
influences of degrading agents.
1.2 This part of IS0 9806 applies to all types of solar collectors, including integral collector storage systems but
excepting tracking concentrating collectors.
1.3 This part of IS0 9806 defines procedures for testing collectors under well-defined and repeatable conditions,
but does not include pass/fail criteria for the test results.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part
of IS0 9806. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of IS0 9806 are encouraged to investigate the possibility of applying the
most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently
valid International Standards.
Specifica fion and classification of jnstrumen ts for measuring hemispherical solar
IS0 9060: 1990, Solar energy -
and direct solar radiation.
IS0 9459-l :I 993, Solar heating - Domestic water heating systems - Part 7: Performance rating procedure using
indoor test methods.
Domestic water heating systems - Part 2: Outdoor test methods for system
IS0 9459-2:1995, Solar heating -
performance characterization and yearly performance prediction of solar-only systems.
Part 7: Thermal performance of glazed liquid heating co/-
IS0 9806-I : 1994, Test methods for solar collectors -
lectors including pressure drop.
I SO 9806-3: -1) Test methods for solar collectors - Part 3: Thermal performance of unglazed liquid heating CO/-
lectors (sensibl; heat transfer only) including pressure drop.
I) To be published.
1

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SIST ISO 9806-2:1997
0 IS0
IS0 9806=2:1995(E)
3 Definitions
For the purposes of this part of IS0 9806, the definitions given in IS0 9806-I and the following definitions apply.
ector in which the space between the absorber and the cover is evacuated to a
3.1 collector, evacuated: Col
pressure < 3 kPa.
system: Solar heating system in which the solar collector also functions as a heat
3.2 integral collector storage
(water) storage tank.
33 irradiation: Incident energy per unit area of surface, found by the integration of irradiance over a specified
time interval.
It is normally expressed in megajoules per square metre.
The time interval specified is often an hour or a day.
NOTE 1
3.4 stagnation conditions (in solar energy systems): Conditions of temperature and pressure existing when the
system has attained a quasi-steady state after the flow of the heat transfer fluid has stopped, but the absorber
continues to receive significant solar radiation.
3.5 steady-state: Status of a solar collector when the heat removal rate (including losses) is equal to the solar
energy input rate.
4 General
The tests in this part of IS0 9806 shall be carried out in the sequence shown in table 1, using three collectors (A,
B and C) of any given type.
Tests may be omitted from the sequence upon agreement of all parties involved or at the discretion of the test
laboratory. Changes in the test sequence shall be reported with the test results and the reasons for deviation shall
be given.
For some qualification tests, a part of the collector may have to be tampered with in some way, for example a hole
may have to be drilled in the back of the collector to attach a temperature sensor to the absorber. In these cases
care should be taken to ensure that any damage caused does not affect the results of subsequent qualification
tests, for example by allowing water to enter into a previously raintight collector.
NOTE 2 This sequence has been determined with a view to minimizing test costs while ensuring that the possible effects
of each degrading influence are likely to be evaluated in a later test. (For example, rain penetration may result if a collector is
distorted by exposure to high temperatures.)
5 Internal pressure tests for absorbers
5.1 Metallic absorbers for liquid heating collectors
5.1 .I Objective
The absorber is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service.
5.1.2 Apparatus and procedure
The apparatus, shown in figure 1, consists of a hydraulic pressure source (electrical pump or hand pump), a safety
valve, an air-bleed valve and a pressure gauge with an accuracy of 5 % of the actual reading. The air-bleed valve
shall be used to empty the absorber of air before pressurization.
2

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SIST ISO 9806-2:1997
0 IS0
IS0 9806-2: 1995(E)
The metallic absorber is filled with water at room temperature and pressurized to the test pressure for the test
period. This pressure is maintained while the absorber is inspected for swelling, distortion or ruptures.
Table 1 - Test sequence
Test
Sequence Clause Collector
1 5 Internal pressure A
A
2 6 High-temperature resistance’)
A, B and C
3 7 Exposure
A
4 8 External thermal shock*)
5 9 Internal thermal shock A
A
6 10 Rain penetration
A
7 11 Freeze resistance
5 Internal pressure (retest) A
8
I
9 Thermal performances) A
12 Impact resistance (optional) A or B
IO
Final inspection
11 13 A, B and C
I) For organic absorbers, the high-temperature resistance test shall be performed first in order to determine the collector
stagnation temperature needed for the internal pressure test.
2) The external thermal shock test may be combined with the exposure test.
3) The thermal performance test shall be carried out in accordance with the procedures given in IS0 9806-I or IS0 9806-3
for glazed or unglazed liquid heating collectors and IS0 9459-l or IS0 9459-2 for integral collector storage systems.
Air-bleed
valve
Fluid pipe sealed
ssure Safety
valve
Collector with
pressure
source
- Schematic for internal pressure test of metallic absorbers for liquid heating collectors
Figure 1

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SIST ISO 9806-2:1997
IS0 9806-2: 1995(E)
5.1.3 Test conditions
5.1.3.1 Temperature
absorbers are pressure-tested at ambient temperature within the range 5 “C to 30 “C.
Metallic
5.1.3.2 Pressure
times the maximum
The test pressure is either th e manufacturer’s stated maximu m test press ure or I,5 collector
operating pressure specified by the manufactu rer, whichever is lower.
The test pressure is maintained for 10 min.
5.1.4 Results
The collector shall be inspected for leakage, swelling and distortion. The results of this inspection shall be reported
together with the values of pressure and temperature used and the duration of the test. If the applied test pressure
was less than I,5 times the maximum collector operating pressure specified by the manufacturer, this shall be
reported.
5.2 Liquid heating absorbers made of organic materials (plastics or elastomers)
5.2.1 Objective
The absorber is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service while operating at elevated temperature. The tests are carried out at elevated temperatures, because
the pressure resistance of an organic absorber may be adversely affected as its temperature is increased.
5.2.2 Apparatus and procedure
neumatic pressure source, and a means of heating the absorber
The apparatus consi sts of either a hydraulic or a p
to the required test temperature
The characteristics of a solar irradiance simulator shall be the same as those of the simulator used for steady-state
efficiency testing of liquid heating solar collectors (see IS0 9806-I).
The test conditions specified in 5.2.3 shall be maintained for at least 30 min prior to test and for the full duration
of the test.
The pressure in the absorber is raised in stages as specified in 5.2.3, and the absorber is inspected for swelling,
distortion or rupture after each increase in pressure. The pressure is maintained while the absorber is being in-
spected.
For safety reasons, the collector shall be encased in a transparent box to protect personnel in the event of ex-
plosive failure during this test.
5.2.2.1 Organic absorbers for use in unglazed collectors (test temperature < 90 “C)
Where the maximum test temperature is below 90 “C, absorbers may be submerged in a heated water bath and
pressure-tested. The pressurized fluid supply to the absorber shall be fitted with a safety valve, air-bleed valve (if
required) and pressure gauge having an accuracy of 5 % of the actual reading. Apparatus is shown in figure 2.
5.2.2.2 Organic absorbers for use with oil-based fluids (test temperature > 90 “C)
When the test temperature exceeds 90 “C, the absorber may be connected to a hot oil circuit. The absorber and
hot oil circuit are then pressurized. The hot oil circuit shall be fitted with a safety valve, air-bleed valve and pressure
gauge having an accuracy of 5 % of the actual reading.
4

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SIST ISO 9806-2:1997
0 IS0
IS0 9806=2:1995(E)
The absorber may be heated by any of the following methods:
a) connecting a heater in the oil circuit (figure3);
b) heating the whole collector in a solar irradiance simulator (figure4);
c) heating the whole collector outdoors under natural solar irradiance (figure4).
Safety measures should be taken to protect personnel from hot oil in the event of explosive failure during this test.
5.2.2.3 Organic absorbers - high-temperature pneumatic pressure test
The absorber may be pressure-tested using compressed air, when heated by either of the following methods:
a) heating the whole collector in a solar irradiance simulator (figure5);
b) heating the whole collector outdoors under natural solar irradiance (figure 5).
The compressed air supply to the absorber shall be fitted with a safety valve and a pressure gauge having an ac-
curacy of 5 % of the actual reading.
Safety Pressure
valve
ww
Air-bleed vaive
(for hydraulic
Hydraulic or
testing only)
pneumatic
pressure source
Temperature sensor
Organic absorber
L
Heated water bath
Schematic for internal pressure test of organic absorbers for use in unglazed collectors
Figure 2 -
5

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SIST ISO 9806-2:1997
IS0 9806-2: 1995(E)
Air-bleed
valve
Fluid pipe sealed
Hot oil
source
Safety
valve
Temperature
sensor
organic absorber
Circulating
pump
Figure 3 - Schematic for internal pressure test of organic absorbers for use with oil-based fluids (hot oil
source)
Air-bleed
valve
Natural or simulated
A
solar radiation
I
ture
Pyranometer on
collector plane
Fluid pipe
Hydraulic
pressure
source
Figure 4 - Schematic for internal pressure test of organic absorbers for use with oil-based fluids (test
under solar irradiance)

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SIST ISO 9806-2:1997
IS0 9806-2: 1995(E)
Natural or simulated
solar radiation
Ambient
tempera ture
se nsor
Pressure Safety
valve
ww e
Pyranometer on
Collector with
collector plane
organic absorber
Pneumati
pressure
source
Fl uid pipe se
Figure 5 - Schematic for internal pressure test of organic absorbers (pneumatic test under solar
irradiance)
5.2.3 Test conditions
5.2.3.1 Temperature
For absorbers made of organic materials, the test temperature is the maximum temperature which the absorber
will reach under stagnation conditions.
One of the alternative sets of reference conditions given in table 2 shall be used to determine the test temperature,
depending on the climate in which the collector will be used.
The calculations employed to determine the test temperature are included in annex B and shall either:
- use measured collector performance characteristics, or
- extrapolate from average values, measured in the high-temperature resistance test (6.3), of the global solar
irradiance (natural or simulated) on the collector plane, the surrounding air temperature and the absorber tem-
perature.
The test temperature for integral collector storage systems shall be 85 “C for class A and class B climate reference
conditions and 100 “C for class C.
- Climate reference conditions to determine test temperatures for internal pressure test of
Table 2
organic absorbers
Value for climate class
Climate parameter
Class A Class B Class C
Temperate Sunny
Very sunny
1 000 1 100
Global solar irradiance on collector plane, G (W/m*) > 1 200
Surrounding air temperature, ta (“C) 30 40
> 40
7

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SIST ISO 9806-2:1997
0 IS0
IS0 9806-2: 1995(E)
5.2.3.2 Pressure
The test pressure shall be I,5 times the maximum collector operating pressure specified by the manufacturer.
For absorbers made of organic materials, the pressure shall be raised to the test pressure in equal stages of
0,2 bar*) (approximately) and maintained at each intermediate pressure for 5 min. The test pressure shall then be
maintained for at least 1 h.
5.2.4 Results
The collector shall be inspected for leakage, swelling and distortion. The results of the inspection shall be reported.
Full details of the test procedure used, including the temperature, intermediate pressures and test periods used,
shall be reported with the test results.
53 . Air heating collectors with metallic absorbers
5.3.1 Objective
The collector is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service, including pressures which may arise when the airflow is blocked on the other side of the collector from
the fan.
5.3.2 Apparatus and procedure
The apparatus, shown in figure6, consists of a controllable air source or suction fan, capable of supplying the
specified values of positive or negative pressure at the maximum allowable collector leakage flowrate. An airflow
meter having an accuracy of 5 % is installed to measure the rate of leakage, and a pressure gauge having an ac-
curacy of 5 % of the actual reading is installed to measure the pressure in the absorber.
Pressure
gauge
collector with
Leaka Air source or
w
airflo w meter sue tion fan
Schematic for internal pressure test of air heating collectors with metallic absorbers
Figure 6 -
The air source or suction fan, airflow meter and pressure gauge are connected to the collector, and other pipe
connections to the collector are sealed.
The collector is brought to the test pressure with air at ambient temperature, for the specified test period.
The collector is maintained at the test pressure while it is inspected for swelling, distortion or ruptures.
For safety reasons, the collector shall be encased in a transparent box to protect personnel in the event of ex-
plosive failure during this test.
2) 1 bar = 100 kPa.
8

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SIST ISO 9806-2:1997
0 IS0
IS0 9806=2:1995(E)
5.3.3 Test conditions
5.3.3.1 Temperature
Air heating collectors with metallic absorbers are pressure-tested at ambient temperature.
5.3.3.2 Pressure
The test pressure is I,2 times the maximum collector operating pressure difference above or below atmospheric
pressure, as specified by the manufacturer.
The test pressure is maintained for 10 min.
5.3.4 Results
The collector shall be inspected for swelling, distortion or ruptures. The results of the inspection shall be reported
together with the rate of air leakage, and the values of pressure and temperature and the test period used for the
test.
5.4 Air heating absorbers made of organic materials (plastics or elastomers)
5.4.1 Objective
The collector is pressure-tested to assess the extent to which it can withstand the pressures which it might meet
in service, including pressures which may arise when the airflow is blocked on the other side of the collector from
the fan. Because the pressure resistance of collectors with absorbers made of organic materials is expected to
be significantly reduced at higher temperatures, a pressure test at an elevated temperature shall be used.
5.4.2 Apparatus and procedure
The apparatus (see figure 7) consists of a controllable air source or suction fan, capable of supplying the specified
values of positive or negative pressure at the required temperature, and at the maximum allowable collector
leakage flowrate. A flowmeter having an accuracy of 5 % to measure the leakage and a pressure gauge having
an accuracy of 5 % of the readings taken during the test are also required.
Circulating fan
Air heater
Temperature fi
sensor
Figure 7 - Schematic for internal pressure test of air heating collectors with organic absorbers

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SIST ISO 9806-2:1997
(0 IS0
IS0 9806-2: 1995(E)
The collector is connected to an air-heating loop in such a way that air flows downwards into the collector. The
pressure gauge is connected to the collector either in a separate opening of the collector or in the heating loop
close to the outlet of the collector. While circulating air through the collector, the air is heated to the test tem-
perature and maintained there for the test period. The collector and the heating loop are pressurized or depress-
urized in stages to the test pressure, which is then maintained for the test period.
After the test period, the temperature and pressure are maintained while the collector is inspected for swelling,
distortion or ruptures. The collector is also inspected for swelling, distortion or ruptures after each rise in pressure.
For safety reasons, the collector shall be encased in a transparent box to protect personnel in the event of ex-
plosive failure during this test.
5.4.3 Test conditions
5.4.3.1 Temperature
which the absorber
absorbers made of organic materials, the test temperature is the maximum temperature
For
will reach under stagnation conditions.
One of the alternative sets of reference conditions given in table 2 shall be used to determine the test temperature,
depending on the climate in which the collector will be used.
The test temperature shall be determined from measurements made during the high-temperature resistance test
specified in clause 6, using the expression included in annex B.
5.4.3.2 Pressure
The test pressure shall be I,2 times the maximum collector operating pressure difference above or below at-
mospheric pressure, as specified by the manufacturer.
For absorbers made of organic materials, the pressure shall be raised to the test pressure in equal stages of
0,2 bar (approximately) and maintained at each intermediate pressure for 5 min. The test pressure shall then be
maintained for at least 1 h.
5.4.4 Results
The collector shall be inspected for leakage, swelling and distortion. The results of the inspection shall be reported.
Full details of the test procedure used, including the temperature, intermediate pressures and test periods selec-
ted, shall be reported with the test results.
6 High-temperature resistance test
6.1 Objective
This test is intended to assess rapidly whether a collector can withstand high irradiance levels without failures such
as glass breakage, collapse of plastic cover, melting of plastic absorber, or significant deposits on the collector
cover from outgassing of collector material.
6.2 Apparatus and procedure
The collector shall be tested outdoors, or in a solar irradiance simulator, or in a hot fluid loop of the type described
in 5.2.2.2. A schematic for testing outdoors or in a simulator is shown in figure 8.
The characteristics of the solar irradiance simulator to be used for the high-temperature resistance test shall be
those of the solar irradiance simulator used for steady-state efficiency testing of liquid heating solar collectors in
accordance with IS0 9806-I.
10

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SIST ISO 9806-2:1997
IS0 9806=2:1995(E)
A
Natur aL or simulated
solar radiation
lid
Ambient
temperature
FL sensor
Le
Pyranometer on
collector plane
J Fluid pipe sealed
L
Figure 8 - Schematic for high-temperature resistance test (outdoors or in simulator)
If a hot fluid loop is used, the hot fluid shall be circulated from the bottom to the top of the collector with a constant
inlet temperature, using a flowrate similar to that defined for collector efficiency testing (see IS0 9806-I).
NOTE 3 It is recognized that the thermal stresses induced by the hot fluid loop test may not be equivalent to the thermal
stresses induced by heating externally using natural or simulated solar irradiance.
The collector is mounted outdoors or in a solar simulator, and it is not filled with fluid. All of its fluid pipes are
sealed to prevent cooling by natural circulation of air except one, which is left open to permit free expansion of
air in the absorber.
A temperature sensor is attached to the absorber to monitor its temperature during the test. The sensor shall be
positioned at two-thirds of the absorber height and half the absorber width. It shall be fixed firmly in a position to
ensure good thermal contact with the absorber. The sensor shall be shielded from solar radiation.
NOTES
4 When testing collectors, such as evacuated tubular collectors, for which it is not appropriate to measure the stagnation
temperature at the absorber, the temperature sensor should be placed at a suitable location in the collector, and this location
should be clearly described with the test results.
5 In some cases, such as evacuated absorbers, it may be difficult to attach a thermocouple to the absorber. In such cases,
instead of attaching a thermocouple to the absorber, the testing laboratory may partially fill the absorber with a special fluid,
seal the absorber and measure the pressure in the absorber. The relationship between the internal pressure in the absorber
and its temperature should be known from the standard vapour pressure/temperature relationship for the fluid.
The test is performed for a minimum of 1 h after steady-state conditions have
been established, and the collector
65 . .
is subsequently inspected for signs of damage as specified in
11

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SIST ISO 9806-2:1997
0 IS0
IS0 9806-2: 1995(E)
6.3 Test conditions for testing outdoors or in a solar irradiance simulator
One of the alternative sets of reference conditions given in table3 shall be used, depending on the climate in
which the collector will be used.
Table 3 - Climate reference conditions for high-temperature resistance test
Value for climate class
4-- I
Climate parameter
Class A Class B Class C
Temperate Sunny Very sunny
Global solar irradiance
on collector plane, G (W/m*) 950 - 1 049 1 050 - 1 200 > 1 200
25,0 - 29,9 30 - 40 > 40
Surrounding air temperature, ta (“C)
Surrounding air speed (m/s)
I I
6.4 Test conditions for testing in a hot fluid loop
If a hot fluid loop is used, then the fluid temperature to be used in the test is the maximum temperature which
the collector will reach under stagnation conditions.
One of the alternative sets of reference conditions given in table 2 shall be used to determine the test temperature,
depending on the climate in which the collector will be used.
The calculations employed to determine the test temperature are included in annex B and shall either:
- use measured collector performance characteristics, or
- extrapolate from average values of solar irradiance (natural or simulated) on the collector plane, surrounding air
temperature and absorber temperature, measured by exposing the collector to available climate conditions
(outdoors, or in
...