Abstract A dynamic collector model for testing collectors and collector arrays under non-stationary operation is described. The aim of the model is to characterize the behaviour of a wide range of flat-plate collectors. The model takes explicitly into account the dependence of the heat loss coefficient on the temperature and the wind velocity as well as the dependence of optical frequency on the incident angle of irradiance. The validation of the model is carried out by outdoor data for a flat-plate vacuum collector. The Dynamic System Testing algorithm is used to identify the collector parameters. The test is repeated with independent test sequences in order to analyse the reproducibility and predictive power. First, the impact of these variations on the yearly collector array energy yield for various climatic zones is presented. Second, the identified parameters from one set of measurement sequences are used to predict the collector energy gain for another independent measurement sequence. The standard deviations of the identified parameters, optical efficiency and heat loss coefficient, do not exceed 2% and 10% respectively.