This paper analyses the performance of a rooftop photovoltaic (PV) plant installed on the city rooftops in south China and a desert PV plant in remote desert in northwest China. A subsystem of the rooftop PV plant and a subsystem of the desert PV plant were monitored by a data acquisition system. The results showed that the performance radio (PR) of the rooftop PV subsystem and the desert PV subsystem was 0.88 and 0.80, respectively. The analysis showed that PR was not influenced by reference yield (Yr) except Yr lower than 1.0 h/d. The final yield (Yf) increased with the increasing of Yr. The array capture loss radio (LRc) of the desert PV subsystem was 15.56% and it was much higher than 5.11% of the rooftop PV subsystem. The main reason is considered that the desert PV plant which located in dry, windy and dusty region in northwest China has higher dirt losses and line losses than that of rooftop PV plant which located in rainy and humid region in south China. The loss ratio of balance of system components (LRBOS) of the rooftop PV subsystem was a little higher than that of the desert PV subsystem. The main loss of the desert PV subsystem was array capture loss while the main loss of the rooftop PV subsystem was loss of balance of system components.