A new method for testing the performance of flat-plate solar collectors

In this study, a new method is proposed for determining the thermal performance parameters of a flat-plate water heating collector. A parametric identification principle is applied to a mathematical model of the collector operating in a real system. The advantages of the method are that it does not need a sophisticated testing system, it avoids the problem of regulating the inlet fluid temperature (which must be held constant during the tests in the standard procedures) and a cloudless sky is not essential. Solar radiation of 600 W m⁻² was chosen as a threshold to start experiments. Applied to a flat-plate collector with a single-glazed cover, the proposed method gave satisfactory results for the determination of its thermal performance coefficients. To verify the adequacy of the present method, it was used to predict the outlet fluid temperature. The results indicate a satisfactory agreement between predicted and measured values with a correlation coefficient of 0.99 and an error of 0.4%. We propose that performance results will be presented as a technical sheet showing collector features and accompanied with a curve giving the correlation between estimated and measured output temperature of the collector fluid.