Improved in situ performance testing of line-concentrating solar collectors: Comprehensive uncertainty analysis for the selection of measurement instrumentation

Accurate and complete performance evaluation is playing a major role in the further development of concentrating solar collectors. To ensure dependable test results, an appropriate testing and evaluation procedure is required. Moreover, the selection and installation of suitable measurement instrumentation are essential for obtaining reliable data for the performance evaluation. The quality of the measurement instrumentation greatly influences the representativeness of the test results. Details on the measurement instrumentation recommended for the testing of low-temperature solar collectors have already been provided in the testing standard EN ISO 9806:2013. Due to the larger dimensions of concentrating collectors and thus different working temperatures and mass flow rates, these recommendations cannot be directly applied for the testing of concentrating solar collectors. A good selection of measurement instrumentation will always be a trade-off between feasibility, cost of the instrumentation and its associated uncertainties. For this reason, it is crucial for every testing and certification institution to assess the quality of measurement data during the instrumentation selection process. Until now, this aspect has been sparsely addressed in the relevant literature concerning collector testing procedures. However, uncertainty examinations have become particularly relevant for in situ testing, in which the choice of measurement instrumentation has to be adapted to the specific measurement situation on-site. In situ testing is considered to be particularly beneficial (if not even indispensable) for concentrating collectors in terms of cost effectiveness and feasibility.