ISO 9459-5:2007

INTERNATIONAL ISO
STANDARD 9459-5
First edition
2007-05-15
Solar heating — Domestic water heating
systems —
Part 5:
System performance characterization by
means of whole-system tests and
computer simulation
Chauffage solaire — Systèmes de chauffage de l'eau sanitaire —
Partie 5: Caractérisation de la performance des systèmes au moyen
d'essais effectués sur l'ensemble du système et par simulation sur
ordinateur
Reference number
©
ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 2
4 Symbols, units and nomenclature . 4
5 Apparatus . 5
5.1 Mounting and location of the SDHW system . 5
5.2 Test facility . 8
5.3 Instrumentation. 10
5.4 Location of sensors. 10
6 Test method. 12
6.1 General. 12
6.2 Test conditions . 12
6.3 Test sequences . 14
6.4 Data acquisition and processing . 17
7 Identification of system parameters . 19
7.1 Dynamic fitting algorithm . 19
7.2 Options . 19
7.3 Constants . 19
7.4 Skip time . 20
7.5 Parameters . 20
8 Performance prediction. 20
8.1 Yearly performance prediction and reporting . 20
8.2 Reference conditions . 20
Annex A (normative) Basis of dynamic SDHW system testing. 21
Annex B (normative) Validation of the test method . 24
Annex C (normative) Test report . 25
Annex D (informative) Hardware and software recommendations . 30
Bibliography . 35

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9459-5 was prepared by Technical Committee ISO/TC 180, Solar energy, Subcommittee SC 4,
Systems — Thermal performance, reliability and durability.
ISO 9459 consists of the following parts, under the general title Solar heating — Domestic water heating
systems:
⎯ Part 1: Performance rating procedure using indoor test methods
⎯ Part 2: Outdoor test methods for system performance characterization and yearly performance prediction
of solar-only systems
⎯ Part 3: Performance test for solar plus supplementary systems (withdrawn)
⎯ Part 4: System performance characterization by means of component tests and computer simulation
⎯ Part 5: System performance characterization by means of whole-system tests and computer simulation
iv © ISO 2007 – All rights reserved

Introduction
International Standard ISO 9459 has been developed to help facilitate the international comparison of solar
domestic water heating systems. Because a generalized performance model which is applicable to all
systems has not yet been developed, it has not been possible to obtain an international consensus for one
test method and one standard set of test conditions. It has therefore been decided to promulgate the currently
available simple test methods, while work continues to finalize the more broadly applicable procedures. The
advantage of this approach is that each part can proceed on its own.
ISO 9459 is divided into five parts within three broad categories, as described below.
Rating test
ISO 9459-1:1993, Solar heating — Domestic water heating systems — Part 1: Performance rating procedure
using indoor test methods, involves testing for periods of 1 day for a standardized set of reference conditions.
The results, therefore, allow systems to be compared under identical solar, ambient and load conditions.
Black-box correlation procedures
ISO 9459-2:1995, Solar heating — Domestic water heating systems — Part 2: Outdoor test methods for
system performance characterization and yearly performance prediction of solar-only systems, is applicable to
solar-only systems and solar-preheat systems. The performance test for solar-only systems is a ‘black-box’
procedure which produces a family of ‘input-output’ characteristics for a system. The test results may be used
directly with daily mean values of local solar irradiation, ambient air temperature and cold-water temperature
data to predict annual system performance.
ISO 9459-3:1997, Solar heating — Domestic water heating systems — Part 3: Performance test for solar plus
supplementary systems (now withdrawn), applied to solar plus supplementary systems. The performance test
was a ‘black-box’ procedure which produced coefficients in a correlation equation that could be used with daily
mean values of local solar irradiation, ambient air temperature and cold-water temperature data to predict
annual system performance. The test was limited to predicting annual performance for one load pattern.
Testing and computer simulation
ISO/AWI 9459-4, Solar heating — Domestic water heating systems — Part 4: System performance
characterization by means of component tests and computer simulation, a procedure for characterizing annual
system performance, uses measured component characteristics in the computer simulation program
‘TRNSYS’. Procedures for characterizing the performance of system components other than collectors are
also presented in this part of ISO 9459. Procedures for characterizing the performance of collectors are given
in other International Standards.
This part of ISO 9459 (i.e. ISO 9459-5) presents a procedure for dynamic testing of complete systems to
determine system parameters for use in the “Dynamic System Testing Program” (reference [2]). This software
has been validated on a range of systems; however, it is a proprietary product and cannot be modified by the
user. Implementation of the software requires training from a test facility experienced with the application of
the product. This model may be used with hourly values of local solar irradiation, ambient air temperature and
cold-water temperature data to predict annual system performance.
The procedures defined in ISO 9459-2, ISO 9459-3, ISO 9459-4 and ISO 9459-5 for predicting yearly
performance allow the output of a system to be determined for a range of climatic conditions.
The results of tests performed in accordance with ISO 9459-1 provide a rating for a standard day.
The results of tests performed in accordance with ISO 9459-2 permit performance predictions for a range of
system loads and operating conditions, but only for an evening draw-off.
The results of tests performed in accordance with ISO 9459-3 permitted annual system predictions for one
daily load pattern.
The results of tests performed in accordance with ISO 9459-4 or ISO 9459-5 are directly comparable. These
procedures permit performance predictions for a range of system loads and operating conditions.
System reliability and safety will be dealt with in ISO 11924, Solar heating — Domestic water heating
systems — Test methods for the assessment of protection from extreme temperatures and pressures.
Introduction to ISO 9459-5
The expanding market for Solar Domestic Hot-water (SDHW) systems demands a standardized test method
for SDHW systems, which makes possible accurate long-term performance prediction for arbitrary conditions
from a test as short, simple and cheap as possible.
Two facts make this goal difficult to reach.
a) The SDHW system gain depends on many different conditions (e.g., irradiance, ambient temperature,
draw-off profile and cold-water temperature). Therefore, a sufficient number of parameters are needed to
predict the yearly system gain sufficiently accurately for arbitrary conditions.
b) The system state, that is, the temperature profile inside the store, needs a long time to 'forget' initial
conditions; a typical time constant may be one day or more. Since several parameters need to be
determined, several system states must occur during the test. If a test method did not take into account
the system state dependence on the past, and thus the dynamic behaviour of the system, the minimum
testing times would be quite long (up to several months).
The objective of the method described in this part of ISO 9459 is to minimize experimental effort by keeping
the test duration short and avoiding extensive measurements. To compensate for the relatively small amount
of experimental data, mathematical tools are used to extract as much information as possible from the test
data, while being robust enough to avoid being misled by unimportant transient effects.
There are no requirements for
...