ABSTRACT
The SOLar Energy METer SOLEMET measures the energy gain of solar domestic hot water systems according to the draft ISO standard DP9459 for dynamic system testing.
The energy gain of solar domestic hot water systems depends on many factors such as system design, installation, load, insulation, the weather, etc. Most of these factors are invariable in a specific installation. However, the weather normally follows a yearly cycle and the actual yearly gain can only be measured over a period of a year. This is expensive and not very practical. Therefore a method was developed to reduce the measuring period.
In this so-called DST method, the parameters of a generic SDHW-system model are calculated from actually measured data. The SDHW system is modelled, taking into account the real situation of all system components and the actual system load. Using the mathematical model of the SDHW system that is being investigated and a reference meteorological year, it is possible to calculate the energy gain over that year.
Valid parameters of the model can only be found if the system has been measured under conditions that cover the full variety of system states during a year. In practice it appears that this can be achieved in much less than a year without too much intervention during the measuring period. Under laboratory conditions this is even easier to achieve. The data acquisition requirements and the practical implementation of a measuring set-up are described. The decision criteria which are used to stop measuring, as well as the data processing procedure are explained. The DST method is discussed and some results are presented.
