BS ISO 9459-5:2007 - Page 2

Solar heating. Domestic water heating systems. System performance characterization by means of whole-system tests and computer simulation | Status: Current, Confirmed

1 Scope This part of ISO 9459 specifies a method for outdoor laboratory testing of solar domestic hot-water (SDHW) systems. The method may also be applied for in-situ tests, and also for indoor tests by specifying appropriate draw-off profiles and irradiance profiles for indoor measurements. The system performance is characterized by means of whole-system tests using a 'black-box' approach, i.e. no measurements on the system components or inside the system are necessary. Detailed instructions are given on the measurement procedure, on processing and analysis of the measurement data, and on presentation of the test report. The theoretical model described in reference [1] is used to characterize SDHW system performance under transient operation. The identification of the parameters in the theoretical model is carried out by a parameter-identification software program (see Annex A). The program finds the set of parameters that gives the best fit between the theoretical model and the measured data. A wide range of operating conditions shall be covered to ensure accurate determination of the system parameters. Measured data shall be pre-processed before being used for identification of system parameters. The identified parameters are used for the prediction of the long-term system performance for the climatic and load conditions of the desired location, using the same model as for parameter identification. The system prediction part of the theoretical model requires hourly values of meteorological data (e.g. test reference years) and specific load data, as described in Annex C. This part of ISO 9459 can be applied to the following SDHW systems including:

1. a) systems with forced circulation of fluid in the collector loop;
2. b) thermosiphon systems;
3. c) integral collector storage (ICS) systems;.

provided that for b) and c) the validation requirements described in Clause B.2 of Annex B are satisfied. Systems are limited to the following dimensions1).

• — The collector aperture area of the SDHW system is between 1 and 10 m2.
• — The storage capacity of the SDHW system is between 50 and 1 000 litres.
• — The specific storage-tank volume is between 10 and 200 litres per square metre of collector aperture area.

Limits to the application of this International Standard.

1. 1) This part of ISO 9459 is not intended to establish any safety or health requirements.
2. 2) This part of ISO 9459 is not intended to be used for testing the individual components of the system. However, it is permitted to obtain test data of components in combination with a test according to the procedure described here.
3. 3) The test procedure cannot be applied to SDHW systems containing more than one storage tank. This does not exclude preheat systems with a second tank in series. However, only the first tank is considered as part of the system being tested.
4. 4) Systems with collectors having non-flat plate-type incident-angle characteristics can be tested if the irradiance in the data file(s) is multiplied by the measured incident-angle modifier prior to parameter identification. The same irradiance correction should, in this case, also be used during any performance predictions based on the identified parameters.
5. 5) The test procedure cannot be applied to SDHW systems with overheating protection devices that significantly influence the system behaviour under normal operation2).
6. 6) The test procedure cannot be applied to integrated auxiliary solar systems, with a high proportion of the store heated concurrently by the auxiliary heater. The results of the tests are only valid when the resulting parameter faux < 0,75.
7. 7) The test procedure cannot be applied to SDHW systems with an external load-side heat exchanger in combination with a temperature-dependent pump.