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:
a) systems with forced circulation of fluid in the collector loop;
b) thermosiphon systems;
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.