Collector tests according to ISO 9806 / EN 12975
In order to determine the efficiency parameters of solar thermal collectors according to ISO 9806 or EN 12975, two different procedures can be used: the steady state test method and the quasi dynamic test method.
During the steady state test, all boundary conditions such as solar radiance, ambient temperature and collector inlet temperature must be constant. After recording data points over a representative range of operating conditions, the collector efficiency curve can be determined by means of multilinear regression using the least square method.
During the quasi dynamic test the boundary conditions must vary. Based on a series of measurements, specific collector parameters are determined, as well. With the quasi dynamic test method, additional parameters such as the heat capacity of the collector and the incident angle modifier coefficient can be determined in addition to the efficiency curve.