Abstarct: One of the problems of today's world is the reduction of fossil fuels and environmental pollution caused by fossil fuels in order to provide power, cooling and heating to provide people with comfort. Therefore, solar systems are one of the effective ways to meet these needs, in order to reduce fossil fuel consumption and reduce pollutant emissions. On the other hand, solar energy is a clean and abundant energy that can play a useful role in providing part of these needs. The combination of heating systems and solar systems can have a profound effect on human life and the environment. Therefore, in this research, a flat panel solar collector is being used for energy analysis in an office building in Gorgan city. The capacity of the study is 647,000 kWh of heating in 2012 baxsed on energy bills. The amount of radiation and energy absorbed by the collector through coding in the software environment of MATLAB has been studied. The set has been presented in four different scenarios, the results of which indicate that half of the thermal load with the solar system and the other half with boiler support the best scenario.