Experiences and Lessons Learned From 30 Years of Dynamic Collector Testing, Modelling and Simulation
Abstract
Dynamic testing and modeling (in contrast to Steady State line of action) of solar collectors is to prefer in most climates, except for the most extreme locations with clear skies every day. A very important part of dynamic testing and modeling is not only the thermal capacitance correction, but also the split of the solar radiation absorption modeling, into beam and diffuse and the modeling of the collectors’ incidence angle dependency for both beam and diffuse radiation. These optical features are in most situations more important than the accuracy of the dynamic and thermal loss part of the model. This can be seen from the statistical analyze when evaluating test data. The t-ratios i.e. the parameter values divided by their standard deviations, are generally much higher (often 10 times higher) for the optical parameters than for the thermal loss ones. There are also important details concerning solar radiation measurements for beam and diffuse including alignment of sensors and test object, that are often not considered, which will be discussed and lessons learned will be given. A misalignment of just a few degrees of the collector test stand or the solar sensors will immediately show up in a dynamic test evaluation, especially when analyzing the incidence angle modifier behavior and thermal capacitance of a collector.