Diesel power plants are still the main choice for supplying isolated grids in Indonesia. Although this kind of power plant is easy to install, it has a high cost of energy (COE) mainly due to the cost of diesel fuel. Besides, Indonesia as a tropical country has a high intensity of solar radiation. Moreover, the investment cost of PV power plant is getting lower and it does not require high operation cost. Thus, the implementation of PV power plant is considered promising in Indonesia, and the idea of combining diesel power plants with PV in isolated grids arises to increase the efficiency of the COE. Apart from the economical aspect, the technical aspect of a hybrid diesel-PV power system implementation needs to be studied as well. In this study, the impact of the PV power plant interconnection to the existing grid is analysed in terms of the power flow and the transient stability using the DIgSILENT PowerFactory software. Furthermore, a load-sharing scheme is applied to some diesel generator units. According to the simulation result, the hybrid power system operated within the allowable voltage limits. After some transient events occurred, the hybrid power system was able to maintain its stability. © Published under licence by IOP Publishing Ltd.