Parameter effects on design and performance of flat plate solar collectors

Abstract Under steady-state and transient state conditions, efficiency and warming-up time of flat plate water collectors are calculated. The effects of the variation of a great many parameters are presented. Proper consideration of these effects is important when meteorological conditions are unfavorable. Comparison of collector performance in summer and winter shows the importance of collector inclination, and the effect of pipe spacing. A rule of thumb is given for the approximate transformation of diurnal irradiance curves into effective constant irradiance values. For the conditions considered here an effective irradiance of about 400 W/m 2 in June yields an efficiency of 57 per cent and an effective irradiance of 300 W/m 2 in December gives 46.5 per cent.