Electrical performance comparison of a rooftop photovoltaic system and an open-rack photovoltaic system

Abstract

This paper analyses the performance of a rooftop photovoltaic (PV) system installed in south China and an open rack photovoltaic system in remote desert in northwest China. A subsystem of the rooftop system and a subsystem of the desert PV system are monitored by a movable monitoring system. The results showed that the performance ratio (PR) of the rooftop subsystem and the open rack PV subsystem is 0.88 and 0.80 respectively. The analysis showed that PR is not influenced by Yr except Yr lower than 1.0 h/d. The final yield Yf increased with the increasing of reference yield Yr. The Loss Ratio (LRc) of the open rack PV subsystem is 15.51% and it is much higher than 15.51% of the rooftop subsystem. The main reason is considered as much higher dirt losses and line losses of the open rack PV subsystem in rainy and humid region in south China than that of the rooftop subsystem in dry, windy and dusty region in northwest China. The Balance of System Loss Ratio (LRBOS) of the rooftop subsystem is a little higher than that of the open rack PV subsystem. The main losses of the rooftop subsystem is LRBOS while the main losses of the open rack PV subsystem is LRc.