Both air and water cooled PV/T collectors have enjoyed growing attentions in recent years. Investigators have reported PV/T research data within a wide range of control parameters. In this paper, the effects of the major control parameters on the thermal/electrical performance of PV/T collectors are compiled and reviewed. Figures and tables are provided to give an overall picture about how PV/T performance could be improved in terms of these parameters. Although investigators understand the effects of different parameters, the improvement of PV/T performance by optimizing these parameters has not been fully realized