摘要： The purpose of this study was to analyze the effect of solar irradiance in the integration of photovoltaic plants (PV) on the stability of the electric power distribution system. The stability aspects assessed were the stability of the distribution network and the stability response of the synchronous generator which work in parallel with the PV generator. Distribution grid stability includes voltage and frequency stability. The stability response of synchronous generators includes power angle stability, active power stability, and reactive power stability. All aspects of stability were simulated based on four different cases of irradiance, namely 550 W/m2, 650 W/m2, 850 W/m2, and 1000 W/m2. PV generators were connected to a distribution grid using an inverter with MPPT and PV systems without batteries. This study was applied to a case of electrical distribution system in Gorontalo province, Indonesia. One distribution feeder in Gorontalo Province was connected a photovoltaic system of 2000 kWp and synchronous generators that work in parallel. The distribution system was modelled in a single-line diagram of 13-buses. The measurement of every solar radiation intensity change was conducted in every electrical distribution power system change. This study showed that high irradiation in PV plants affects the voltage and frequency stability on the grid by increasing proportionately. However, the high irradiation has an effect on increasing power oscillation at synchronous generators.