Direct characterisation of the annual performance of solar thermal and heat pump systems using a six-day whole system test

Systems that provide space heating and domestic hot water are characterized by dynamic operating conditions. For a reliable evaluation of the general system performance, dynamic system test procedures are a more reliable, more reproducible and faster way than using steady-state component test results in combination with annual system simulation or others extrapolation schemes. However, the utilization of dynamic whole system testing was so far hindered by the cost and time associated with the laboratory measurements, and by a lack of scientifically justified procedures for the determination of suitable test profiles. This paper presents an analysis of the suitability of using a six-day sequence for the direct characterization of a solar and heat pump system. The new six-day sequence was developed to perform a benchmark test and its representativeness was verified with one-hundred different solar and heat pump system configurations. It was found that some independent variables lead to a predictable deviation in the performance evaluation based on the six-day sequence compared to whole-year figures, that can be greatly reduced by simple correction factors. For the different configurations, the correction factors reduced the standard deviation of the energetic performance results to 2.5%. (C) 2019 Elsevier Ltd. All rights reserved.