Results and analysis of a round robin test program for liquid-heating flat-plate solar collectors

A round robin test program was conducted to determine the intercompatibility of thermal performance data on 2 liquid-heating flat-plate solar collectors. Efficiency tests were performed at 21 test facilities, distributed across the United States, using a common test procedure. The results were statistically analyzed and showed a relatively large spread in the measured values of collector efficiency. Data from approximately half the facilities were selected for detailed analysis. A collector analytical model was used to show that less than 1 3 of the chi-square for a second order polynomial could be attributed to different environmental conditions from facility to facility. In general, data from a single facility were consistent and the majority of scatter was attributed to systematic uncertainties from facility to facility. When the data from six participants reportedly adhering to the requirements of ASHRAE Standard 93-77 were analyzed, the scatter was found to be within normal limits expected for the test procedure.