At present

the number of existing buildings in China is very large. In order to reduce the energy consumption of existing buildings

solar photovoltaic panels can be laid on the surface of buildings to provide lighting and office electricity demand for buildings. Taking the research building of Jilin University of Architecture and Technology as the research object

the PVsyst software is used to conduct simulation research on the integrated photovoltaic system of the existing building

and the analysis shows that the system has a high power generation from April to August. In the system

the solar incident Angle correction coefficient and the operating temperature of photovoltaic modules cause losses of 2.8% and 3.7%

respectively.These losses can be reduced by changing the angle of photovoltaic modules and improving the operating environment of photovoltaic modules. To sum up

it is feasible to use PVsyst software to simulate the integrated photovoltaic building system

analyze the losses of the system

and put forward the optimization method.