A method for the dynamic testing and evaluation of the performance of combined solar thermal heat pump hot water systems

In the present work, a method is proposed for the testing and evaluation of the performance of combined solar thermal heat pump hot water systems. The method is based on the Dynamic System Testing (DST) method for solar thermal systems. The evaluation of the system performance requires the assessment of the heat pump COP. In case the configuration of the examined system allows the direct measurement of the auxiliary source thermal power contribution, the assessment of COP can be performed on the basis of the measurements anticipated by the testing method itself, otherwise a short-term test has to be performed. The method claims to predict the thermal energy provided to the user on an annual basis, as well as the respective electrical energy consumed by the heat pump, which is a quantity of high concern for the user as it determines the operating cost of the system, with an uncertainty level below 10%. The analysis of the results concluded that a further increase of the prediction reliability would demand a modification of the DST method model, in order to include the heat pump operation parameters, thus enabling the acquisition, through testing, of accurate information about the heat pump operation and energy consumption.