Solar energy is a kind of clean energy，the development of the photovoltaic power generation is of important significance for the achievement of low-carbon development in electric power industry.The models and methods on evaluation of low-carbon benefits of grid connected photovoltaic power generation projects are studied.Firstly，the carbon emissions（or emission reduction）characteristics and economic benefits composition are analyzed from the following four aspects:revenue of generation capacity，cost of photovoltaic，improvement efficiency of system losses，and cost of system reserve capacity.And the corresponding low-carbon benefit models and economic benefit models are established.Then，combined with the low-carbon and economic characteristics of photovoltaic power generation，the low-carbon comprehensive benefits evaluation model of photovoltaic power generation is created thereby，and the concept of carbon emission payback period is put forward.The example based on the typical operating data verifies the validity of the models and methods mentioned.The analysis results show that the photovoltaic power generation has a great advantage in low-carbon comprehensive benefits，compared to conventional power generation.