Because of some of the renewable energy types, some of the energy storage types and DC consumption, DC grid is an inevitable approach in the power system. This study is investigated the DC grid connected PV system's performance under irradiation and temperature variations. In order to improve the performance of the system, the DC-DC boost converter is designed according to the desired specifications. The maximum power point tracking (MPPT) method and PI controller are implemented to the boost converter in order to provide maximum power to the DC grid. Moreover, the DC grid is modeled as a bipolar low voltage (LV) DC grid form. Modeling and simulation of the DC grid connected PV system is performed in PSCAD. Two cases are simulated in the system. The results depending on the proposed model show that a direct proportion occurs between PV array power and the irradiation, and an inverse proportion happens between PV array power and the temperature.