ON THE MEASUREMENT OF THE ISTANTANEOUS EFFICIENCY OF SOLAR THERMAL COLLECTORS WITH A MODIFIED EN 12975 TEST FACILITY

In Europe the thermal efficiency of the solar collectors is measured by following the Standard EN 12975-2. However, in the literature the opportunity to obtain faster and cheaper evaluations is also recognized. In order to give an answer to this request, a new test equipment is proposed. Starting from the basic scheme of the standard steady-state method, a new equipment for the measurement of the instantaneous efficiency has been realized. This equipment allows a fast evaluation of the performance in real environmental conditions. The main difference lies in the procedure used to fix the different test conditions. Although the equipment is not totally conforming to EN 12975-2, the results are quite comparable and the reliability of procedure and equipment is demonstrated